Priorities of Nano Geometries in Suspension

Priorities of Nano Geometries in Suspension | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Priorities of Nano Geometries in Suspension Imtiaz Ahmad, Hidayat Ullah Khan, Rahim Jan This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4531195/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The yield collective effect that is generated by each member of the LC phase largely depends on a uniform dispersion of nanoparticles. Evaporation techniques have been used to complete several fluidic-assisted designs. We examine isolated arrays of heterogeneous nanoparticles, taking into account the free entropic volume effect, comb- and brush-effect, electrostatic, and Van der Waals effects. The crystallographic facets of suspended particles and capping agents on their surfaces determine the optimal arrangement of shapes and orientations. It has been discovered that self-assembling activities occur prior to substrate deposition in nanoparticles with both flat and curved geometries. The drying capillaries drive the structures to develop into more aligned and tightly packed, making it easier to bring all of their shapes in suspension together due to dominant attractive interactions. We investigated some noteworthy cases that shed light on the quantitative and significant factors that are involved in constructing well-organized systems. LC- phases Nanocrystals Assembly Crystallographic facets steric interaction Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 1. Introduction Metallic nanoparticles have been broadly studied in terms of their ability to self-assemble into well-organized supercrystals [ 1 – 4 ]. These supercrystals demonstrated not only the inherent qualities of individual nanoparticle building blocks, but also unique collective optical, electrical, and mechanical capabilities that are changeable by the mesostructured [ 5 , 6 ]. The self-assembly of nanoparticles is a complex process that involves numerous interactions including van der Waals attraction, Coulombic forces, steric repulsion, capillary forces, etc.[ 7 – 9 ]. Highly organized single supercrystals might hold the key to understanding complicated chemical and physical phenomena including surface plasmon-based sensing, pressure-induced interparticle coalescence, and optoelectronic coupling [ 10 – 12 ]. In order to investigate the relationship between structure and property that links nanomaterials to real-world applications, it is critical to produce supercrystals big enough to be consistently worked on and examined using a range of characterization techniques. Large ordered arrays with little structural flaws are also essential for device integration. Physical characteristics such as electrical, magnetic, mechanical, optical, and thermal properties depend not only on the material, but also on its structures, sizes, and shapes. For instance, For example, a stranded wire is more flexible than solid wires of the same total cross-sectional area; a honeycomb structure provides a material with relatively high out-of-plane compression properties and minimal density; and nanomaterials exhibit special properties not shown by the same materials in bulk [ 13 , 14 ]. In particular, the impact of shape and size is important because of the potential uses of nanostructures in biosensing and biomedical devices [ 15 , 16 ]. Nano superstructures have captured the interest of nanoscience and nanotechnology researchers due to their tremendous potential in various fields. According to Frenkel [ 17 ], dense arrays are favored for nano superlattices as the self-assembly of hard particles is usually dominated by entropy-driven maximization of the packing density. Nanoparticles are a great platform to develop sensors because of changes in their interactions caused by variations in the relative position of the particles, shape, and quantity. [ 18 – 20 ]. The optimal assembly processes are reversible and may be regulated by carefully designing the building blocks, their surroundings, and the interactions between the particles [ 9 , 21 ]. After decades of intensive study, it is now possible to make nanomaterial building blocks with ever-improving monodispersity, yield, and large-scale manufacturing. These building blocks can have any composition, shape, or size. Using nanoparticles with particular features to create micro- or macro-scale materials is the next major challenge. The fundamental goal of bottom-up self-assembly protocols is to overcome this difficulty. To predict and attain control over crystallographic structures for intended applications, it is crucial to investigate the mechanisms and interactions that encourage the assembly of nanoshapes, especially in suspension. In this work, we studied various gold nanoshapes and their confined convective gatherings in the coffee-stain ring. The particle geometries employed included nanorods, nanocubes, nanospheres, and nanopyramids. Gold nanoparticles stabilized by the capping agent (CTAB) were suspended in water and dried on the SiO 2 substrate as diluted suspension droplets. The study found that the capping molecule organization mapping and the surface shape of the nanoparticle aid in the assembly process. In light of the experimental findings, we investigate the interactions that the capping agent generates, including Van der Waals, electrostatic, depletion, and steric impact. The position-dependent potential in suspension and scenario-specific topologies in monolayers are analyzed quantitatively and qualitatively. 2. Experimental 2.1 Materials Sodium hydroxide (NaOH, 99.999%, Aldrich), sodium borohydrate (NaBH 4 , 99%, Aldrich), Hydrogen tetrachloroaurate (HAuCl 4 ·3H 2 O, 99.999%, Aldrich), ascorbic acid (AA, 99%, Merck), silver nitrate (AgNO 3 , 99%, Acros), cetyltrimethylammonium bromide (CTAB, Aldrich, 98%), and hydrochloric acid (HCl, 37%, Merck) were all used as received without further purification. All water that was used in the synthesis was of Milli-Q quality (18.2 MΩcm), produced in a Simplicity 185 system (Millipore). 2.2 Syntheses To synthesize gold nanostructures, a two-step seed-mediated method as reported by Nikoobakht and El-Sayed [ 22 ] was employed. Firstly, 10 ml of CTAB (0.1M) was mixed with 25µL of HAuCl 4 (0.1M) to create CTAB-coated seed particles. After that, 60 µL of ice-cold NaBH 4 (0.1M) was added, and for 15 minutes, it was continuously stirred. The production of gold seeds is indicated by the solution's rapid change to pale brown. For one hour, this solution was let to stand at room temperature. The growth solution for gold nanocubes was prepared by combining 10 mL of CTAB (0.1 M) with 50 µL of HAuCl 4 (0.1M). With vigorous stirring, this solution was maintained at 30°C for 25 minutes to fully dissolve the CTAB. After that, 20 µL of room temperature AgNO 3 (0.1M) was added. Subsequently, 70 µL of ascorbic acid (0.1M) and 100 µL of HCl (1M) were added. Lastly, the growth solution was mixed with 25µL of the seed solution, and the mixture was allowed to sit at room temperature for the whole night. The growth mixture for the CTAB-stabilized gold nanospheres was made by combining 10 mL of CTAB (0.1M) with 40 µL of HAuCl 4 (0.1M). This mixture was vigorously stirred and maintained at 25°C for an hour. Next, 10 µL of room temperature AgNO 3 (0.1M) was added. 150 µL of HCl (1M) and 90 µL of ascorbic acid (0.1M) came next. Finally, 50 µL of seeds were added to the growth solution, and the mixture was allowed to sit at room temperature for the whole night. The synthesis of gold nanopyramids was carried out in a single step by dissolving 10 mL (0.2 M) of CTAB in water at 35°C for a minimum of 20 minutes. After that, 200 µL (0.1M) of NaOH and 30 µL (0.1M) of AA were added while stirring continuously. Next, 25 µL of HAuCl 4 (0.1M) was added. Lastly, 50 µL (0.01M) of AgNO 3 was added, and the mixture was allowed to slowly warm up overnight. Similarly, the growth solution for the synthesis nanorods was made by mixing 10 mL of CTAB (0.1M) with 50 µL of HAuCl4 (0.1M). For thirty minutes, this mixture was maintained at 35°C to fully dissolve the CTAB. Thereafter, 20 µL of AgNO3 (0.1M) was added while the solution was kept at 25°C. Subsequently, 70 µL of 0.1M ascorbic acid and 100 µL of (1M) HCl were added. Ultimately, the growth solution was mixed with 24 µL of the seed solution. Overnight at 25°C, this solution was kept undisturbed. To get rid of extra CTAB, the nanorod suspensions were centrifuged for 10 minutes at 15,000 rpm before being used. Also, to separate the spherical nanoparticles from the nanorods, the same growth fluid was centrifuged once more for five minutes at 5600 rpm. The precipitate, which is generally made up of spheres, was carefully separated from the supernatant, which is mostly made up of nanorods, at the bottom of the centrifuge tube. The suspensions of nanorods were refrigerated. The distinction between nanospheres and nanorods is not entirely selective. The spheres are byproducts of the different quantities of spheres present in the suspensions. 2.3 Deposition SiO 2 substrates were ultrasonically cleaned in distilled water at room temperature for 15 minutes before being used for drop casting. Substrates were cleaned twice with distilled water before drying in a nitrogen flow. Suspension droplets (2 µL) from each solution were deposited on a clean SiO 2 substrate and evaporated at room temperature. Within 2 hours, the solvent had vanished completely, leaving a coffee-stain ring on the surface. 2.3 Characterization Helium ion microscope (HIM) measurements were carried out with an ultra-high vacuum (Zeiss Orion Plus) helium ion microscope [ 23 ]. The microscope is outfitted with a detector (Everhardt-Thornley) for secondary electron detection. A micro-channel plate located below the final lens (just above the sample) enables a qualitative investigation of backscattered helium. This detector produces images in which dark regions correspond to light elements with low backscatter probability, while bright areas with high backscatter yield correspond to heavy components in the specimen. HIM images of used particles are shown in Fig. 1 b. High-resolution scanning electron microscopy (SEM; on a Merlin Zeiss 1550 system) was used for imaging our samples with nanoparticle deposits; typical voltages in the range of 0.1–30 kV are accessible. Images used in this work were obtained at an accelerating voltage of 2 kV. Ultraviolet-visible spectroscopy (UV-Vis) is a technique for measuring the optical absorption of ultraviolet and visible light as it passes through a substance, which can be solid or liquid. All measurements were performed with an Ocean Optics (HR2000 + spectrometer) using the Spectra-Suite software program and a UV-Vis (Mikropack model DH-2000-BAL) light source. To analyze nanoparticles floating in water, we utilized typical semi-micro UV cuvettes of 12.5mm×12.5mm×45mm, with a liquid distance of 10mm. The employed cuvettes have a capacity of 1.5 ml, allowing for the examination of lower suspension quantities. Typical UV-Vis spectrums of the nanoparticles are shown in Fig. 1 a. 3. Results and Discussion HIM images of gold cube-like nanoparticles with flat and curved surface configurations are shown in Fig. 2 . The dominant Van der Waals attraction suppresses the electrostatic repulsion caused by the negative bromide head at the exposed ends of the CTAB capping molecules on the surface of the gold particles [ 21 ]. As a result, suspended floating nanoparticles are going to group together to lower their fluctuation energy. Such an environment in suspension will facilitate steric molecules to interact. Figure 3 shows such brushing (radially adjusted molecules) and combing mechanisms (linearly adjusted molecules). Figures 2 c and 2 d show how the capping molecules adjust radially (brush effect) against the gold nanocubes, whereas Figs. 2 a and 2 b show the combing molecular packing of gold nanocubes. The asymmetrical molecular mapping in suspension is less visible because of the surface molecular adjustment effect. That is why the majority of constructed structures exhibit surface combing (molecular arrays on flat surfaces) and brushing (radial molecular arrangements on curved surfaces) effects. Using relationships previously reported, the electrostatic (Eq. 1.1 ) and van der Waals (Eq. 1.2 ) potentials between two nanocubes have been considered as important interactions in suspension [ 21 ]. Electrostatic repulsive potential (see black curve in Fig. 4 ): $${U}_{FF}^{electrostatic}\left(d\right)=W\sqrt{\raisebox{1ex}{${D}_{1}{D}_{2}$}\!\left/ \!\raisebox{-1ex}{${D}_{1}+{D}_{2}$}\right.}\left\{{\int }_{d}^{\infty }\raisebox{1ex}{${E}_{FF}^{electrostatic}\left(x\right)$}\!\left/ \!\raisebox{-1ex}{$\sqrt{x-d}$}\right.dx\right\}$$ 1.1 ………… Van der Waals attractive potential (see red curve in Fig. 4 ): $${U}_{FF}^{vdW}\left(d\right)=\raisebox{1ex}{$AW$}\!\left/ \!\raisebox{-1ex}{$24{d}^{\frac{3}{2}}$}\right.\sqrt{\raisebox{1ex}{${D}_{1}{D}_{2}$}\!\left/ \!\raisebox{-1ex}{${D}_{1}+{D}_{2}$}\right.}$$ 1.2 ……………………………………………. Where d is the surface-to-surface separation between two particles, W (length in case of anisotropic particle) is the length of the gold nanorod, \({\varvec{D}}_{1} \text{a}\text{n}\text{d} {\varvec{D}}_{2}\) are the diameters of the two closing particles in suspension. In the case of two similar nanocubes of dimension 50nm, the potential response is illustrated in Fig. 4 . The potential curve (VdW + electrostatic) depicts more depth of the potential as well as the distance between two nanocubes decreases in suspension and becomes maximum at 7nm. This potential is responsible for inducing close-packed formation in suspension. The CTAB stabilized gold nanospheres-like particles show similar arrangements shown by nanocubes (see Fig. 5 ). HIM image of two CTAB coated gold nanospheres arranged in such a way that their curve surfaces face each other suggesting brush-like radial configuration as depicted in Fig. 5 a. For more than two particles, the similar arrays demonstrated the curve surface molecular arrangement is shown in Fig. 5 b and 5 c. In addition, flat comb-like facets of gold nanoparticles with linear molecular configuration are depicted in Fig. 5 b. For more than four spherical nanoparticles the mixed (comb- and brush-like) packing is shown in Fig. 5 d. Suggesting that sterically probable order is followed by these particles. But, before short-range molecular interaction comes into play, these nanoparticles must approach each other in suspension. For that, we need to know whether there exists any potential that facilitates their close-packed arrangement. The electrostatic and Van der Waals potentials for the 30nm nanospheres are therefore plotted and shown in Fig. 6 . The interaction potential (electrostatic + VdW) is attractive and has the maximum value at a separation (between the two spheres) of 7nm that amounts to the potential value of -5.58kT as shown in Fig. 6 . Such potential allow nanoparticle in suspension to come closer and consequently their surface molecules begin to dictate positioning and packing of particles following the comb and brush effect shown in Fig. 3 . The assembly of anisotropic gold nanorods is the most fascinating one. Specifically, nanorods are preferably arranged with their kind (shape and size) [ 21 ]. The probability of a curved surface in between the nanorods is very low. For two reasons, firstly owing to the different arrangement of capping molecules at the flat and curve geometries whereas secondly, the free volume phenomenon does not allow high thermal fluctuating free volume. The most feasible position for the nanosphere to attach with is the end of a nanorod as depicted in Fig. 7 a. For nanorods in suspension, the most probable poisoning is face-to-face (FF) alignment as shown in Fig. 7 b and 7 D. Such alignment is also feasible both sterically (comb-effect) and according to free volume entropy. Nothing in the surroundings with such face-to-face aligned nanorods result-oriented (making an angle with end nanorods) end-to-end (EE) arrays as shown in Fig. 7 c. Such orientation is necessary to achieve a reduction in free volume that will result in low energy position for the assembled arrays on the substrate. The interaction potential for these nanorods with ~ 60nm length and ~ 10nm width is plotted in Fig. 8 . The potential (VdW + electrostatic) reaches the bottom of the potential well at the closest approach that amounts to 7nm. This potential enables gold nanorods to organize in close-packed smectic crystallographic arrangements, facilitating the comb-effect to stir various shapes out of the more probable arrays. An other unique shape that will aid in developing an understanding of the assembly behavior of nano geometries in suspension is the CTAB stabilized nanopyramid. These structures owing to their unsmooth surface will be difficult for them to align parallel to the surface. However, such geometry will align preferably along the flat surfaces with each other through comb-like mechanism as shown in Fig. 9 c. A pyramid of width 60nm and length 90nm is shown in Fig. 9 a. Two closing nanopyramids oriented facing flat ends following comb effect as depicted in Fig. 9 b. The pyramids flat geometries predominantly demonstrated sterically favored arrangements and long end flat geometries (FF) showing the lowest potential depth − 10.11kT at 6.6nm separation from each other. The assembling potential (VdW + electrostatic) curve for the pyramids' specific orientation is shown in Fig. 10 . Hence, the priority is suspension for the nanopyramids along with other shapes is again sterically and energetically as well as free volumetrically feasible positioning. The nanoparticles considered above were geometrically defined shapes with flat and curved crystallographic facets. Ultimately, we considered a CTAB-stabilized gold nano shape that shows complex structures [ 24 ]. Some tail-like CTAB stabilized gold nanoparticles are shown in Fig. 11 . To plot their interaction potential in suspension we approximated these particles as nanorods of length 50nm and width 12nm. The depth of the potential well amounts to -7.4kT at a distance of 6.8nm from other particles as shown in Fig. 12 . Suggesting interaction will be attractive between two particles in suspension and close-packed arrangements are expected. However, the curves and flat sides show preferential steric arrangement as depicted in Fig. 13 . The monolayer close-packed arrays of such dispersed shapes seem to follow the free volume effect. The free volume effect is schematically shown in Fig. 14 . The energy of nanoparticles will be high if these particles occupy more volume (thermally unstable state in suspension) whereas the energy state will be low if these particles are assembled in such a way that their packing occupies a majority of volume leaving negligible free volume as depicted in Fig. 14 from top to bottom panel. The priorities of CTAB gold nanoparticles of various shapes suggest that position-dependent nano interaction in stable convective evaporation techniques often leads to close-packed liquid crystalline (LC) phases of nanoparticles. This is true for low concentrations of nanoparticles in suspension. These nanoparticle solutions were prepared in 10mL of water and the calculated concentration of nanoparticles was in the range of 10 14 cm −3 . This solution was diluted by adding 10mL of water which will correspond to approximately 10 7 cm −3 nanoparticles. The former concentration leads to multi-layer arrays of nanoparticles [ 25 ] whereas the latter concentration deposits predominantly monolayer arrays [ 26 ]. However, dilution causes loosely and occasionally close-packed islands. The possible reason for such an effect could be the limited arrival of the particles to the three-phased contact line of the evaporating droplet. Allowing islands to deposit over the substrate surface and the contact line moves (recede) inward for the next deposition of islands. The main objective of this work is to study the effect of such a low number deposition of nanoparticles for validation of some concepts that are frequently associated with structural orientation and choices of nanoparticle (facets) geometry dictated in suspension. For instance, if there exists some attractive position-dependent potential in suspension then there is a possibility that close-packed arrays of these nanoparticles are formed in suspension just before settling on the substrate surface. If this is true then one can expect that further stirring of deposit islands may happen with the drying capillaries. Moreover, the capping agent around nanoparticles will also follow the comb- and brush- effect during assembling both in suspension and on the surface. Our results show that irrespective of the shape of the nanoparticle, the favorable arrangement for nanoparticles is to align with similar steric facets of the nanoparticle. Such behavior of nanoshapes is specifically helpful in predicting the formation of various LC phases in suspension. On the other hand, we can say that nano interaction brings these particles closer to the contact line where the molecular structural arrangement at the various crystallographic facets of the nanoparticle will induce shape shuffling especially with a more fluctuating environment near the droplet edge. The free volume effect also comes into play as particles in suspension do not wish to flout in isolation with higher thermal vibration (higher energy state). To reduce their energy, they need to stabilize with another nearby particle and consequently, the more stable state in suspension is the arrangement where nanoparticles occupy less volume. This free-volume effect can be realized more visibly in the case of complex-shaped nanoparticles. Where each different nanoshape particle tried to accommodate the space according to its size, shape, and twists in their structure. To quantify the effect of nanoparticles shape (short-axis and long-axis variations) with respect to the minimum potential depth that gives the maximum strength of attraction between any two nanoshapes in suspension is presented in Fig. 15 . As the system consists of different shapes and complex tail-like geometries, we considered two parameters such as long-axis and short-axis of nanoparticles to approximate the numerical values for theoretical consideration of dimensions. Such consideration allows us to analyze the shape effect of nanoshapes in terms of minimum potential function. The long-axis and short-axis of the nanoparticles are plotted against the minimum value of the potential as depicted in Fig. 15 a. Reduction in the long (red) and short (green) axis of nanoparticles show a linear decrease in potential minima. The higher the value of the short/long axis, the higher the potential depth for suspended nanoparticles. The ratio of the short and long axis corresponding to the shape of the nanoparticle shows that the depth of the potential well increases exponentially in the short axis as shown in Fig. 15 b. The variation of potential depth for two nanoparticles with respect to the shape for each value of the long-axis with changing short-axis values is shown in Fig. 15 c. Such exponential variations highlighting the fact that the depth of the potential well will maximum for large value of both short and long axis. As a result, one must expect thick and long (see Fig. 15 d) nanoparticles aligned preferentially with their own kind. Such shape effect is illustrated in Fig. 16 (a-d). Additionally, their size distribution is shown in the lower panels of Fig. 16 . The line scan shows that the bigger particles like to place with bigger and small follows the small sizes. Such size selectivity in packing justifies both steric comb-brush effect as well as supported by the nano potential situation between the nanoshapes in suspension. 4. Conclusion Various geometrical nanoshapes and a complicated nanoparticle were suspended in water and allowed to settle on a hydrophilic substrate. Their monolayer arrangement was created following the dilution of the sample in order to analyze their assembly process in suspension due to molecular capping arrangements. It was discovered that surfactant-directed mechanisms, such as the comb-brush effect, play an essential role in inducing shape and size effects at the flat and curved ends of nanoshapes. The brush (radially orientated) effect induced by CTAB molecules surrounding the nanoparticles' curve facets likes to join with the similar facets next to it. On the other hand, the flat geometry of nanoparticles with the comb-like effect caused by surfactant molecules arranges with the adjoining flat surface. This effect dictates the orientation of nanoshapes in suspension. Furthermore, the drying capillaries on the surface will swirl them together with the desired aspects. However, conditions must be met for these nanoshapes to get closer to one another in suspension before molecular interactions may take place. For these particles to be able to attain lower energy, there has to be some sort of attractive potential between them. The Van der Waals potential, which brought these nanoshapes together in suspension, is the most important interaction between them. The instances examined here have shown that attractiveness never goes away and that its effectiveness—or the depth of the potential well—increases as its dimensions alter. Nanoparticles' short and long axes significantly affect this potential. Their distinct appealing potential also brought them together with like-minded others. While the thin will be thin, the thick will choose to join with the thicker ones. Similarly, short and long nanoparticles will assemble with short and long shapes. The strong attracting potential in suspension determines the form and size impact. The entropic effect is another crucial metric for closely packed liquid crystalline phases since it demonstrates the free volume effect. The phenomenon is most noticeable in complexed-shaped nanoparticles, where the open spaces between the curving complexed structures exhibit an accumulation of small spheres and other forms. Researchers will be able to estimate and comprehend the shape and size of assemblies with the aid of this work, particularly for achieving monolayer LC phases. Declarations Acknowledgement: This work is carried out at Department of Physics, University of Peshawar. Declaring your interests: I have no potential competing or non-financial interests in publishing this manuscript. Author Contribution Imtiaz Ahmad: Conceptualization, Visualization, Investigation, Supervision, Original draft preparation, data analysis, expertise in self-assembly, Methodology, Experimental work, Data curation.Rahim Jan: Software, data analysis, Suggestions in work discussion. Hidayat Ullah Khan: Writing- Reviewing and Editing. References Wang, Z. et al. Correlating superlattice polymorphs to inter-nanoparticle distance, packing density and surface lattice in assemblies of PbS nanoparticles. Nano Lett. 13, 1303–1311 (2013). Li, R. et al. An obtuse rhombohedral superlattice assembled by Pt nanocubes. Nano Lett. 15, 6254–6260 (2015). Choi, J. J., Bian, K., Baumgardner, W. J., Smilgies, D.-M. & Hanrath, T. Interface-induced nucleation, orientational alignment and symmetry transformations in nanocube superlattices. Nano Lett. 12, 4791–4798 (2012). Bian, K. et al. Shape-anisotropy driven symmetry transformations in nanocrystal superlattice polymorphs. ACS Nano 5, 2815–2823 (2011). Collier, C. P., Saykally, R. J., Shiang, J. J., Henrichs, S. E. & Heath, J. R. Reversible tuning of silver quantum dot monolayers through the metal-insulator transition. Science 227, 1978–1981 (1997). Bian, K., Wang, Z. & Hanrath, T. Comparing the structural stability of PbS nanocrystals assembled in fcc and bcc superlattice allotropes. J. Am. Chem. Soc. 134, 10787–10790 (2012). Kim, J. et al. Polymorphic assembly from beveled gold triangular nanoprisms. Nano Lett. 17, 3270–3275 (2017). Kim, J., Ou, Z., Jones, M. R., Song, X. & Chen, Q. Imaging the polymerization of multivalent nanoparticles in solution. Nat. Commun. 8, 761 (2017). Bishop, K. J. M.; Wilmer, C. E.; Soh, S.; Grzybowski, B. A. Nanoscale Forces and Their Uses in Self-Assembly. Small 2009, 5, 1600−1630. Li, B. et al. Stress-induced phase transformation and optical coupling of silver nanoparticle superlattices into mechanically stable nanowires. Nat. Commun. 5, 4179 (2014). Wu, H. et al. Nanostructured gold architectures formed through high pressure-driven sintering of spherical nanoparticle arrays. J. Am. Chem. Soc. 132, 12826–12828 (2010). Kim, J., Ou, Z., Jones, M. R., Song, X. & Chen, Q. Imaging the polymerization of multivalent nanoparticles in solution. Nat. Commun. 8, 761 (2017). E. Roduner, Chem. Soc. Rev. 2006, 35, 583. 10.1039/b502142c Hideyuki Mitomo, Kuniharu Ijiro, Controlled Nanostructures Fabricated by the Self-Assembly of Gold Nanoparticles via Simple Surface Modifications, Bulletin of the Chemical Society of Japan, Volume 94, Issue 4, April 2021, Pages 1300–1310, https://doi.org/10.1246/bcsj.20210031 Y. Niidome, A. T. Haine, T. Niidome, Chem. Lett. 2016, 45, 488. 10.1246/cl.160124 K. Xu, R. Zhou, K. Takei, M. Hong, Adv. Sci. 2019, 6, 1900925. 10.1002/advs.20190092 D. Frenkel, Order through entropy. Nat. Mater. 14, 9–12 (2015). Hao, Y.; Fang, L.; Deng, Z. Solvo-Driven Dimeric Nanoplasmon Coupling Under DNA Direction. CCS Chem. 2021, 3, 1359–1367. Wang, P.F.; Huh, J.H.; Lee, J.; Kim, K.; Park, K.J.; Lee, S.; Ke, Y. Magnetic Plasmon Networks Programmed by Molecular Self-Assembly. Adv. Mater. 2019 , 31 , 1901364. Tanwar, S.; Kaur, V.; Kaur, G.; Sen, T. Broadband SERS Enhancement by DNA Origami Assembled Bimetallic Nanoantennas with Label-Free Single Protein Sensing. J. Phys. Chem. Lett. 2021, 12, 8141–8150 Ahmad, I.; Zandvliet, H. J. W.; Kooij, E. S. Langmuir 2014, 30, 7953–7961. doi:10.1021/la500980j Nikoobakht B and El-Sayed M A 2003 Chem. Mater. 15 1957. G. Hlawacek, Imtiaz Ahmad, M. A. Smithers, E. S. Kooij, To see or not to see: imaging surfactant coated nano-particles using HIM and SEM, Ultramicroscopy 135, (2013) 89-94. Ahmad, I., & Hussain, A. (2020). Analysis of colloidal nanostructures synthesized through complex route. Inorganic and Nano-Metal Chemistry, 50(12), 1248–1253. https://doi.org/10.1080/24701556.2020.1745836 Imtiaz Ahmad, Hidayat Ullah Khan, Rahim Jan, Sajjad Ahmad Khan, Anisotropic gold nanoparticles crystalizes in multifaceted superstructures, Mater. Res. Express 6 (2019) 105006. Ahmad, I. Deposition and distribution of gold nanoparticles in a coffee-stain ring on the HOPG terraces. Bull Mater Sci 43 , 118 (2020). https://doi.org/10.1007/s12034-020-02094-7 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4531195","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":313221720,"identity":"bae672ca-c8f4-4468-aa71-56c4f282c88b","order_by":0,"name":"Imtiaz Ahmad","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxUlEQVRIiWNgGAWjYBACNiA+wMBgA+HxALEEYS3MIC1pJGhhAGoBgsMkaOETO3/wwI8/5xP7pRsYH7xtY8iTbCDkMOlkhoM9PLcTZ845wGw4t42hWJqQLSAtB3gkbiduuJHAJs3bxpA4jxgtB/8YnANpYf9NtJbDPAkHwLYwg7TMJkKLwWGZA8nGM+ccbJacc06imKD35WcnPv745o+dbL9088EPb8ps8iQOELIGDiQYQcZLJBCtAR6FpGgZBaNgFIyCEQIAUS49qT1qhsYAAAAASUVORK5CYII=","orcid":"","institution":"University of Peshawar","correspondingAuthor":true,"prefix":"","firstName":"Imtiaz","middleName":"","lastName":"Ahmad","suffix":""},{"id":313221721,"identity":"f074a2e7-9f69-4a8b-8f94-c4af235b03a7","order_by":1,"name":"Hidayat Ullah Khan","email":"","orcid":"","institution":"University of Peshawar","correspondingAuthor":false,"prefix":"","firstName":"Hidayat","middleName":"Ullah","lastName":"Khan","suffix":""},{"id":313221722,"identity":"8d3296c6-a287-4687-9bf4-64910bdbd3e4","order_by":2,"name":"Rahim Jan","email":"","orcid":"","institution":"University of Peshawar","correspondingAuthor":false,"prefix":"","firstName":"Rahim","middleName":"","lastName":"Jan","suffix":""}],"badges":[],"createdAt":"2024-06-05 03:51:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4531195/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4531195/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":59126028,"identity":"99edbfac-f67b-4c8a-956a-6109e4509af4","added_by":"auto","created_at":"2024-06-26 15:35:51","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":418740,"visible":true,"origin":"","legend":"\u003cp\u003e(a) UV-Vis spectrum of nano spheres, cubes, pyramids, rods, and worms. (b) HIM images of spheres, a cube, a pyramid, rods, and worms respectively.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/60c43fea20c5d56518a844c1.png"},{"id":59126027,"identity":"4539b05f-0f72-4f2e-b0b8-eef07d0368c4","added_by":"auto","created_at":"2024-06-26 15:35:51","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":450336,"visible":true,"origin":"","legend":"\u003cp\u003e(a) HIM images of two nanocubes assembled with flat surfaces. (b) Zoom in of similar arrangement of cubes with flat surfaces. (c) Draw together of curve edges. (d) Flat and curve symmetries.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/9216d06456a5c09a29389735.png"},{"id":59125357,"identity":"a0834fd1-5358-4b8e-af5c-dd144ad9602b","added_by":"auto","created_at":"2024-06-26 15:27:51","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":358184,"visible":true,"origin":"","legend":"\u003cp\u003eCombing and brushing mechanism of capping molecules on the nanoparticle surface.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/f157025ca4536cee894b3b1c.png"},{"id":59125350,"identity":"8634fb4a-58b0-47e4-a911-c88a00987e1a","added_by":"auto","created_at":"2024-06-26 15:27:51","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":326024,"visible":true,"origin":"","legend":"\u003cp\u003eThe electrostatic (black) and Van der Waals (red) potentials are plotted for the schematic arrangement of the gold nanocubes. The sum of these potentials showing minimum energy state lies around 7nm for this case.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/365d3ae75991da2df6b1a77c.png"},{"id":59125352,"identity":"12b53d70-6dbd-475d-9751-1098b6c2a4a4","added_by":"auto","created_at":"2024-06-26 15:27:51","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":404113,"visible":true,"origin":"","legend":"\u003cp\u003eHIM images of (a) two CTAB coated nanospheres, (c,d) four nanospheres, and (d) more than four nanospheres. The dotted red line indicating flat and curve surface geometry.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/8134ef56306625efe651119f.png"},{"id":59125364,"identity":"1cfadf78-99d2-4b52-9e58-7597b917a33a","added_by":"auto","created_at":"2024-06-26 15:27:52","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":276423,"visible":true,"origin":"","legend":"\u003cp\u003eThe electrostatic (black) and Van der Waals (red) potentials are plotted for the schematic arrangement of the gold nanospheres. The sum of these potentials showing depth of the potential well amounts to -5.58kT.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/48d3884c7bd5d56129a91232.png"},{"id":59125355,"identity":"981ce864-625d-4ab9-9b40-bad12a29f498","added_by":"auto","created_at":"2024-06-26 15:27:51","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":367999,"visible":true,"origin":"","legend":"\u003cp\u003eHIM images of gold (a) sphere and rod, (b) two nanorods, (c) six nanorods face-to-face and end-to-end oriented 120 degrees, and (d) parallel face-to-face and end-to-end\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/abdbef4631fd928d0df17c79.png"},{"id":59125361,"identity":"84b29ef3-9e10-4f94-ae88-bcf614a3ee0e","added_by":"auto","created_at":"2024-06-26 15:27:51","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":264929,"visible":true,"origin":"","legend":"\u003cp\u003eThe electrostatic (black) and Van der Waals (red) potentials for the schematic arrangement of two FF gold nanorods. The sum of these potentials showing depth of the potential well amounts to -8.9kT.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/63e6dd59144c07c72a7b89a0.png"},{"id":59126030,"identity":"f78eaddf-94f4-4d7c-9af8-204d45d84dbb","added_by":"auto","created_at":"2024-06-26 15:35:51","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":242393,"visible":true,"origin":"","legend":"\u003cp\u003eHIM images of (a) a gold pyramid, (b) two EE pyramids, (c) six FF pyramids.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/e87f9866abf99237ec134f7d.png"},{"id":59126032,"identity":"db1b6095-982d-401a-96cb-307babdf6ab1","added_by":"auto","created_at":"2024-06-26 15:35:52","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":396132,"visible":true,"origin":"","legend":"\u003cp\u003eThe electrostatic (black) and Van der Waals (red) potentials for the schematic arrangement of two gold nanopyramids. The sum of these potentials showing depth of the potential well amounts to -10.11kT at 6.6nm.\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/b61022ba6c8644c387cd734d.png"},{"id":59126029,"identity":"e02042fc-6572-4083-8ad0-05ab706cccd9","added_by":"auto","created_at":"2024-06-26 15:35:51","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":342549,"visible":true,"origin":"","legend":"\u003cp\u003eHIM images of (a) two gold-tailed nanoparticle, (b) closely packed of complex shapes, (c) large arrays of packed monolayer.\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/9b1375dbd5b9f1cc6703842d.png"},{"id":59126031,"identity":"3397ecc1-81ad-4b14-899e-a064b28d9200","added_by":"auto","created_at":"2024-06-26 15:35:52","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":284364,"visible":true,"origin":"","legend":"\u003cp\u003eThe electrostatic (black) and Van der Waals (red) potentials for the schematic arrangement of two gold nano tailed particles. The sum of these potentials showing depth of the potential well amounts to -7.4kT at 6.8nm.\u003c/p\u003e","description":"","filename":"12.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/8e6b8bb4aefb0b0fa5d04a08.png"},{"id":59125359,"identity":"aee20c44-d788-455d-a274-8e794fa60c0b","added_by":"auto","created_at":"2024-06-26 15:27:51","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":267231,"visible":true,"origin":"","legend":"\u003cp\u003eHIM images of gold-tailed nanoparticle comb- and brush-like effect.\u003c/p\u003e","description":"","filename":"13.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/f1da3150142f5a569edec9b1.png"},{"id":59125356,"identity":"bb7abd61-d731-43b1-af45-f3d7c0a199ad","added_by":"auto","created_at":"2024-06-26 15:27:51","extension":"png","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":178286,"visible":true,"origin":"","legend":"\u003cp\u003eScheme of free volume effect for complex shapes.\u003c/p\u003e","description":"","filename":"14.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/b16a613b9b38f08df97aee3b.png"},{"id":59125366,"identity":"cde9f9da-7471-4035-a4bc-afe2859c6163","added_by":"auto","created_at":"2024-06-26 15:27:52","extension":"png","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":495977,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Theoretical behavior of two nanoshapes minimum potential variation with respect to their long and short axis variation. (b) Exponential increase in the potential (minima) vs shape (long axis/short axis) of nanoparticle as function of their short-axis variation. (c) Decrease in potential minima vs shape of nanoparticle for various values of the short-axis, the inset showing exponential fall in potential. (d) Scheme of short and long axis analogy.\u003c/p\u003e","description":"","filename":"15.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/01c18584407a62dd42f14daa.png"},{"id":59125365,"identity":"9d339d30-2405-47c4-a8c1-b4044e54b33d","added_by":"auto","created_at":"2024-06-26 15:27:52","extension":"png","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":721931,"visible":true,"origin":"","legend":"\u003cp\u003e(a) SEM images shape preferred arrangement of nano (a) tail-like complex particles, (b) pyramids, (c) thin-thick and long-short rods, (d) spheres of changing size. The lower panel shape effect for various shapes.\u003c/p\u003e","description":"","filename":"16.png","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/381f2cd75ed51ff667e47785.png"},{"id":60856488,"identity":"edaf3461-3910-40f0-a51f-e3fdcdc08380","added_by":"auto","created_at":"2024-07-22 23:02:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8356374,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4531195/v1/f14aa52c-bd0f-4057-a85d-489333daeed0.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003ePriorities of Nano Geometries in Suspension\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eMetallic nanoparticles have been broadly studied in terms of their ability to self-assemble into well-organized supercrystals [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. These supercrystals demonstrated not only the inherent qualities of individual nanoparticle building blocks, but also unique collective optical, electrical, and mechanical capabilities that are changeable by the mesostructured [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The self-assembly of nanoparticles is a complex process that involves numerous interactions including van der Waals attraction, Coulombic forces, steric repulsion, capillary forces, etc.[\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Highly organized single supercrystals might hold the key to understanding complicated chemical and physical phenomena including surface plasmon-based sensing, pressure-induced interparticle coalescence, and optoelectronic coupling [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In order to investigate the relationship between structure and property that links nanomaterials to real-world applications, it is critical to produce supercrystals big enough to be consistently worked on and examined using a range of characterization techniques. Large ordered arrays with little structural flaws are also essential for device integration.\u003c/p\u003e \u003cp\u003ePhysical characteristics such as electrical, magnetic, mechanical, optical, and thermal properties depend not only on the material, but also on its structures, sizes, and shapes. For instance, For example, a stranded wire is more flexible than solid wires of the same total cross-sectional area; a honeycomb structure provides a material with relatively high out-of-plane compression properties and minimal density; and nanomaterials exhibit special properties not shown by the same materials in bulk [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. In particular, the impact of shape and size is important because of the potential uses of nanostructures in biosensing and biomedical devices [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Nano superstructures have captured the interest of nanoscience and nanotechnology researchers due to their tremendous potential in various fields.\u003c/p\u003e \u003cp\u003eAccording to Frenkel [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], dense arrays are favored for nano superlattices as the self-assembly of hard particles is usually dominated by entropy-driven maximization of the packing density. Nanoparticles are a great platform to develop sensors because of changes in their interactions caused by variations in the relative position of the particles, shape, and quantity. [\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The optimal assembly processes are reversible and may be regulated by carefully designing the building blocks, their surroundings, and the interactions between the particles [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. After decades of intensive study, it is now possible to make nanomaterial building blocks with ever-improving monodispersity, yield, and large-scale manufacturing. These building blocks can have any composition, shape, or size. Using nanoparticles with particular features to create micro- or macro-scale materials is the next major challenge. The fundamental goal of bottom-up self-assembly protocols is to overcome this difficulty. To predict and attain control over crystallographic structures for intended applications, it is crucial to investigate the mechanisms and interactions that encourage the assembly of nanoshapes, especially in suspension.\u003c/p\u003e \u003cp\u003eIn this work, we studied various gold nanoshapes and their confined convective gatherings in the coffee-stain ring. The particle geometries employed included nanorods, nanocubes, nanospheres, and nanopyramids. Gold nanoparticles stabilized by the capping agent (CTAB) were suspended in water and dried on the SiO\u003csub\u003e2\u003c/sub\u003e substrate as diluted suspension droplets. The study found that the capping molecule organization mapping and the surface shape of the nanoparticle aid in the assembly process. In light of the experimental findings, we investigate the interactions that the capping agent generates, including Van der Waals, electrostatic, depletion, and steric impact. The position-dependent potential in suspension and scenario-specific topologies in monolayers are analyzed quantitatively and qualitatively.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eSodium hydroxide (NaOH, 99.999%, Aldrich), sodium borohydrate (NaBH\u003csub\u003e4\u003c/sub\u003e, 99%, Aldrich), Hydrogen tetrachloroaurate (HAuCl\u003csub\u003e4\u003c/sub\u003e\u0026middot;3H\u003csub\u003e2\u003c/sub\u003eO, 99.999%, Aldrich), ascorbic acid (AA, 99%, Merck), silver nitrate (AgNO\u003csub\u003e3\u003c/sub\u003e, 99%, Acros), cetyltrimethylammonium bromide (CTAB, Aldrich, 98%), and hydrochloric acid (HCl, 37%, Merck) were all used as received without further purification. All water that was used in the synthesis was of Milli-Q quality (18.2 MΩcm), produced in a Simplicity 185 system (Millipore).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Syntheses\u003c/h2\u003e \u003cp\u003eTo synthesize gold nanostructures, a two-step seed-mediated method as reported by Nikoobakht and El-Sayed [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] was employed. Firstly, 10 ml of CTAB (0.1M) was mixed with 25\u0026micro;L of HAuCl\u003csub\u003e4\u003c/sub\u003e (0.1M) to create CTAB-coated seed particles. After that, 60 \u0026micro;L of ice-cold NaBH\u003csub\u003e4\u003c/sub\u003e (0.1M) was added, and for 15 minutes, it was continuously stirred. The production of gold seeds is indicated by the solution's rapid change to pale brown. For one hour, this solution was let to stand at room temperature.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThe growth solution for gold nanocubes was prepared by combining 10 mL of CTAB (0.1 M) with 50 \u0026micro;L of HAuCl\u003csub\u003e4\u003c/sub\u003e (0.1M). With vigorous stirring, this solution was maintained at 30\u0026deg;C for 25 minutes to fully dissolve the CTAB. After that, 20 \u0026micro;L of room temperature AgNO\u003csub\u003e3\u003c/sub\u003e (0.1M) was added. Subsequently, 70 \u0026micro;L of ascorbic acid (0.1M) and 100 \u0026micro;L of HCl (1M) were added. Lastly, the growth solution was mixed with 25\u0026micro;L of the seed solution, and the mixture was allowed to sit at room temperature for the whole night.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe growth mixture for the CTAB-stabilized gold nanospheres was made by combining 10 mL of CTAB (0.1M) with 40 \u0026micro;L of HAuCl\u003csub\u003e4\u003c/sub\u003e (0.1M). This mixture was vigorously stirred and maintained at 25\u0026deg;C for an hour. Next, 10 \u0026micro;L of room temperature AgNO\u003csub\u003e3\u003c/sub\u003e (0.1M) was added. 150 \u0026micro;L of HCl (1M) and 90 \u0026micro;L of ascorbic acid (0.1M) came next. Finally, 50 \u0026micro;L of seeds were added to the growth solution, and the mixture was allowed to sit at room temperature for the whole night.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThe synthesis of gold nanopyramids was carried out in a single step by dissolving 10 mL (0.2 M) of CTAB in water at 35\u0026deg;C for a minimum of 20 minutes. After that, 200 \u0026micro;L (0.1M) of NaOH and 30 \u0026micro;L (0.1M) of AA were added while stirring continuously. Next, 25 \u0026micro;L of HAuCl\u003csub\u003e4\u003c/sub\u003e (0.1M) was added. Lastly, 50 \u0026micro;L (0.01M) of AgNO\u003csub\u003e3\u003c/sub\u003e was added, and the mixture was allowed to slowly warm up overnight.\u003c/p\u003e\u003cp\u003eSimilarly, the growth solution for the synthesis nanorods was made by mixing 10 mL of CTAB (0.1M) with 50 \u0026micro;L of HAuCl4 (0.1M). For thirty minutes, this mixture was maintained at 35\u0026deg;C to fully dissolve the CTAB. Thereafter, 20 \u0026micro;L of AgNO3 (0.1M) was added while the solution was kept at 25\u0026deg;C. Subsequently, 70 \u0026micro;L of 0.1M ascorbic acid and 100 \u0026micro;L of (1M) HCl were added. Ultimately, the growth solution was mixed with 24 \u0026micro;L of the seed solution. Overnight at 25\u0026deg;C, this solution was kept undisturbed.\u003c/p\u003e\u003cp\u003eTo get rid of extra CTAB, the nanorod suspensions were centrifuged for 10 minutes at 15,000 rpm before being used. Also, to separate the spherical nanoparticles from the nanorods, the same growth fluid was centrifuged once more for five minutes at 5600 rpm. The precipitate, which is generally made up of spheres, was carefully separated from the supernatant, which is mostly made up of nanorods, at the bottom of the centrifuge tube. The suspensions of nanorods were refrigerated. The distinction between nanospheres and nanorods is not entirely selective. The spheres are byproducts of the different quantities of spheres present in the suspensions.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Deposition\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eSiO\u003csub\u003e2\u003c/sub\u003e substrates were ultrasonically cleaned in distilled water at room temperature for 15 minutes before being used for drop casting. Substrates were cleaned twice with distilled water before drying in a nitrogen flow. Suspension droplets (2 \u0026micro;L) from each solution were deposited on a clean SiO\u003csub\u003e2\u003c/sub\u003e substrate and evaporated at room temperature. Within 2 hours, the solvent had vanished completely, leaving a coffee-stain ring on the surface.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Characterization\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eHelium ion microscope (HIM) measurements were carried out with an ultra-high vacuum (Zeiss Orion Plus) helium ion microscope [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The microscope is outfitted with a detector (Everhardt-Thornley) for secondary electron detection. A micro-channel plate located below the final lens (just above the sample) enables a qualitative investigation of backscattered helium. This detector produces images in which dark regions correspond to light elements with low backscatter probability, while bright areas with high backscatter yield correspond to heavy components in the specimen. HIM images of used particles are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb.\u003c/p\u003e \u003cp\u003e High-resolution scanning electron microscopy (SEM; on a Merlin Zeiss 1550 system) was used for imaging our samples with nanoparticle deposits; typical voltages in the range of 0.1\u0026ndash;30 kV are accessible. Images used in this work were obtained at an accelerating voltage of 2 kV.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eUltraviolet-visible spectroscopy (UV-Vis) is a technique for measuring the optical absorption of ultraviolet and visible light as it passes through a substance, which can be solid or liquid. All measurements were performed with an Ocean Optics (HR2000\u0026thinsp;+\u0026thinsp;spectrometer) using the Spectra-Suite software program and a UV-Vis (Mikropack model DH-2000-BAL) light source. To analyze nanoparticles floating in water, we utilized typical semi-micro UV cuvettes of 12.5mm\u0026times;12.5mm\u0026times;45mm, with a liquid distance of 10mm. The employed cuvettes have a capacity of 1.5 ml, allowing for the examination of lower suspension quantities. Typical UV-Vis spectrums of the nanoparticles are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cp\u003eHIM images of gold cube-like nanoparticles with flat and curved surface configurations are shown in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. The dominant Van der Waals attraction suppresses the electrostatic repulsion caused by the negative bromide head at the exposed ends of the CTAB capping molecules on the surface of the gold particles [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. As a result, suspended floating nanoparticles are going to group together to lower their fluctuation energy. Such an environment in suspension will facilitate steric molecules to interact. Figure \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e shows such brushing (radially adjusted molecules) and combing mechanisms (linearly adjusted molecules). Figures \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ec and \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ed show how the capping molecules adjust radially (brush effect) against the gold nanocubes, whereas Figs. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003ea and \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eb show the combing molecular packing of gold nanocubes. The asymmetrical molecular mapping in suspension is less visible because of the surface molecular adjustment effect. That is why the majority of constructed structures exhibit surface combing (molecular arrays on flat surfaces) and brushing (radial molecular arrangements on curved surfaces) effects.\u003c/p\u003e\n\u003cp\u003eUsing relationships previously reported, the electrostatic (Eq. \u003cspan class=\"InternalRef\"\u003e1.1\u003c/span\u003e) and van der Waals (Eq. \u003cspan class=\"InternalRef\"\u003e1.2\u003c/span\u003e) potentials between two nanocubes have been considered as important interactions in suspension [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. Electrostatic repulsive potential (see black curve in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e):\u003c/p\u003e\n\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e$${U}_{FF}^{electrostatic}\\left(d\\right)=W\\sqrt{\\raisebox{1ex}{${D}_{1}{D}_{2}$}\\!\\left/ \\!\\raisebox{-1ex}{${D}_{1}+{D}_{2}$}\\right.}\\left\\{{\\int }_{d}^{\\infty }\\raisebox{1ex}{${E}_{FF}^{electrostatic}\\left(x\\right)$}\\!\\left/ \\!\\raisebox{-1ex}{$\\sqrt{x-d}$}\\right.dx\\right\\}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1.1\u003c/div\u003e\u003c/div\u003e\u003cp\u003e\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u003c/p\u003e\u003cp\u003eVan der Waals attractive potential (see red curve in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e):\u003c/p\u003e\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e$${U}_{FF}^{vdW}\\left(d\\right)=\\raisebox{1ex}{$AW$}\\!\\left/ \\!\\raisebox{-1ex}{$24{d}^{\\frac{3}{2}}$}\\right.\\sqrt{\\raisebox{1ex}{${D}_{1}{D}_{2}$}\\!\\left/ \\!\\raisebox{-1ex}{${D}_{1}+{D}_{2}$}\\right.}$$\u003c/div\u003e\n \u003cdiv class=\"EquationNumber\"\u003e1.2\u003c/div\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;\u0026hellip;.\u003c/p\u003e\n\u003cp\u003eWhere \u003cstrong\u003ed\u003c/strong\u003e is the surface-to-surface separation between two particles, \u003cstrong\u003eW\u003c/strong\u003e (length in case of anisotropic particle) is the length of the gold nanorod, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\varvec{D}}_{1} \\text{a}\\text{n}\\text{d} {\\varvec{D}}_{2}\\)\u003c/span\u003e\u003c/span\u003e are the diameters of the two closing particles in suspension. In the case of two similar nanocubes of dimension 50nm, the potential response is illustrated in Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e. The potential curve (VdW\u0026thinsp;+\u0026thinsp;electrostatic) depicts more depth of the potential as well as the distance between two nanocubes decreases in suspension and becomes maximum at 7nm. This potential is responsible for inducing close-packed formation in suspension.\u003c/p\u003e\n\u003cp\u003eThe CTAB stabilized gold nanospheres-like particles show similar arrangements shown by nanocubes (see Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e). HIM image of two CTAB coated gold nanospheres arranged in such a way that their curve surfaces face each other suggesting brush-like radial configuration as depicted in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ea. For more than two particles, the similar arrays demonstrated the curve surface molecular arrangement is shown in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eb and \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ec. In addition, flat comb-like facets of gold nanoparticles with linear molecular configuration are depicted in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eb. For more than four spherical nanoparticles the mixed (comb- and brush-like) packing is shown in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003ed. Suggesting that sterically probable order is followed by these particles. But, before short-range molecular interaction comes into play, these nanoparticles must approach each other in suspension. For that, we need to know whether there exists any potential that facilitates their close-packed arrangement. The electrostatic and Van der Waals potentials for the 30nm nanospheres are therefore plotted and shown in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e. The interaction potential (electrostatic\u0026thinsp;+\u0026thinsp;VdW) is attractive and has the maximum value at a separation (between the two spheres) of 7nm that amounts to the potential value of -5.58kT as shown in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e. Such potential allow nanoparticle in suspension to come closer and consequently their surface molecules begin to dictate positioning and packing of particles following the comb and brush effect shown in Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003eThe assembly of anisotropic gold nanorods is the most fascinating one. Specifically, nanorods are preferably arranged with their kind (shape and size) [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. The probability of a curved surface in between the nanorods is very low. For two reasons, firstly owing to the different arrangement of capping molecules at the flat and curve geometries whereas secondly, the free volume phenomenon does not allow high thermal fluctuating free volume. The most feasible position for the nanosphere to attach with is the end of a nanorod as depicted in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ea. For nanorods in suspension, the most probable poisoning is face-to-face (FF) alignment as shown in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eb and \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003eD. Such alignment is also feasible both sterically (comb-effect) and according to free volume entropy. Nothing in the surroundings with such face-to-face aligned nanorods result-oriented (making an angle with end nanorods) end-to-end (EE) arrays as shown in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ec. Such orientation is necessary to achieve a reduction in free volume that will result in low energy position for the assembled arrays on the substrate.\u003c/p\u003e\n\u003cp\u003eThe interaction potential for these nanorods with ~\u0026thinsp;60nm length and ~\u0026thinsp;10nm width is plotted in Fig. \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e. The potential (VdW\u0026thinsp;+\u0026thinsp;electrostatic) reaches the bottom of the potential well at the closest approach that amounts to 7nm. This potential enables gold nanorods to organize in close-packed smectic crystallographic arrangements, facilitating the comb-effect to stir various shapes out of the more probable arrays.\u003c/p\u003e\n\u003cp\u003eAn other unique shape that will aid in developing an understanding of the assembly behavior of nano geometries in suspension is the CTAB stabilized nanopyramid. These structures owing to their unsmooth surface will be difficult for them to align parallel to the surface. However, such geometry will align preferably along the flat surfaces with each other through comb-like mechanism as shown in Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003ec. A pyramid of width 60nm and length 90nm is shown in Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003ea. Two closing nanopyramids oriented facing flat ends following comb effect as depicted in Fig. \u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003eb. The pyramids flat geometries predominantly demonstrated sterically favored arrangements and long end flat geometries (FF) showing the lowest potential depth \u0026minus;\u0026thinsp;10.11kT at 6.6nm separation from each other. The assembling potential (VdW\u0026thinsp;+\u0026thinsp;electrostatic) curve for the pyramids\u0026apos; specific orientation is shown in Fig. \u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e. Hence, the priority is suspension for the nanopyramids along with other shapes is again sterically and energetically as well as free volumetrically feasible positioning.\u003c/p\u003e\n\u003cp\u003eThe nanoparticles considered above were geometrically defined shapes with flat and curved crystallographic facets. Ultimately, we considered a CTAB-stabilized gold nano shape that shows complex structures [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e]. Some tail-like CTAB stabilized gold nanoparticles are shown in Fig. \u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003e. To plot their interaction potential in suspension we approximated these particles as nanorods of length 50nm and width 12nm. The depth of the potential well amounts to -7.4kT at a distance of 6.8nm from other particles as shown in Fig. \u003cspan class=\"InternalRef\"\u003e12\u003c/span\u003e. Suggesting interaction will be attractive between two particles in suspension and close-packed arrangements are expected. However, the curves and flat sides show preferential steric arrangement as depicted in Fig. \u003cspan class=\"InternalRef\"\u003e13\u003c/span\u003e. The monolayer close-packed arrays of such dispersed shapes seem to follow the free volume effect. The free volume effect is schematically shown in Fig. \u003cspan class=\"InternalRef\"\u003e14\u003c/span\u003e. The energy of nanoparticles will be high if these particles occupy more volume (thermally unstable state in suspension) whereas the energy state will be low if these particles are assembled in such a way that their packing occupies a majority of volume leaving negligible free volume as depicted in Fig. \u003cspan class=\"InternalRef\"\u003e14\u003c/span\u003e from top to bottom panel.\u003c/p\u003e\n\u003cp\u003eThe priorities of CTAB gold nanoparticles of various shapes suggest that position-dependent nano interaction in stable convective evaporation techniques often leads to close-packed liquid crystalline (LC) phases of nanoparticles. This is true for low concentrations of nanoparticles in suspension. These nanoparticle solutions were prepared in 10mL of water and the calculated concentration of nanoparticles was in the range of 10\u003csup\u003e14\u003c/sup\u003ecm\u003csup\u003e\u0026minus;3\u003c/sup\u003e. This solution was diluted by adding 10mL of water which will correspond to approximately 10\u003csup\u003e7\u003c/sup\u003ecm\u003csup\u003e\u0026minus;3\u003c/sup\u003e nanoparticles. The former concentration leads to multi-layer arrays of nanoparticles [\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e] whereas the latter concentration deposits predominantly monolayer arrays [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]. However, dilution causes loosely and occasionally close-packed islands. The possible reason for such an effect could be the limited arrival of the particles to the three-phased contact line of the evaporating droplet. Allowing islands to deposit over the substrate surface and the contact line moves (recede) inward for the next deposition of islands.\u003c/p\u003e\n\u003cp\u003eThe main objective of this work is to study the effect of such a low number deposition of nanoparticles for validation of some concepts that are frequently associated with structural orientation and choices of nanoparticle (facets) geometry dictated in suspension. For instance, if there exists some attractive position-dependent potential in suspension then there is a possibility that close-packed arrays of these nanoparticles are formed in suspension just before settling on the substrate surface. If this is true then one can expect that further stirring of deposit islands may happen with the drying capillaries. Moreover, the capping agent around nanoparticles will also follow the comb- and brush- effect during assembling both in suspension and on the surface.\u003c/p\u003e\n\u003cp\u003eOur results show that irrespective of the shape of the nanoparticle, the favorable arrangement for nanoparticles is to align with similar steric facets of the nanoparticle. Such behavior of nanoshapes is specifically helpful in predicting the formation of various LC phases in suspension. On the other hand, we can say that nano interaction brings these particles closer to the contact line where the molecular structural arrangement at the various crystallographic facets of the nanoparticle will induce shape shuffling especially with a more fluctuating environment near the droplet edge. The free volume effect also comes into play as particles in suspension do not wish to flout in isolation with higher thermal vibration (higher energy state). To reduce their energy, they need to stabilize with another nearby particle and consequently, the more stable state in suspension is the arrangement where nanoparticles occupy less volume. This free-volume effect can be realized more visibly in the case of complex-shaped nanoparticles. Where each different nanoshape particle tried to accommodate the space according to its size, shape, and twists in their structure.\u003c/p\u003e\n\u003cp\u003eTo quantify the effect of nanoparticles shape (short-axis and long-axis variations) with respect to the minimum potential depth that gives the maximum strength of attraction between any two nanoshapes in suspension is presented in Fig. \u003cspan class=\"InternalRef\"\u003e15\u003c/span\u003e. As the system consists of different shapes and complex tail-like geometries, we considered two parameters such as long-axis and short-axis of nanoparticles to approximate the numerical values for theoretical consideration of dimensions. Such consideration allows us to analyze the shape effect of nanoshapes in terms of minimum potential function. The long-axis and short-axis of the nanoparticles are plotted against the minimum value of the potential as depicted in Fig. \u003cspan class=\"InternalRef\"\u003e15\u003c/span\u003ea. Reduction in the long (red) and short (green) axis of nanoparticles show a linear decrease in potential minima. The higher the value of the short/long axis, the higher the potential depth for suspended nanoparticles. The ratio of the short and long axis corresponding to the shape of the nanoparticle shows that the depth of the potential well increases exponentially in the short axis as shown in Fig. \u003cspan class=\"InternalRef\"\u003e15\u003c/span\u003eb. The variation of potential depth for two nanoparticles with respect to the shape for each value of the long-axis with changing short-axis values is shown in Fig. \u003cspan class=\"InternalRef\"\u003e15\u003c/span\u003ec. Such exponential variations highlighting the fact that the depth of the potential well will maximum for large value of both short and long axis. As a result, one must expect thick and long (see Fig. \u003cspan class=\"InternalRef\"\u003e15\u003c/span\u003ed) nanoparticles aligned preferentially with their own kind. Such shape effect is illustrated in Fig. \u003cspan class=\"InternalRef\"\u003e16\u003c/span\u003e (a-d). Additionally, their size distribution is shown in the lower panels of Fig. \u003cspan class=\"InternalRef\"\u003e16\u003c/span\u003e. The line scan shows that the bigger particles like to place with bigger and small follows the small sizes. Such size selectivity in packing justifies both steric comb-brush effect as well as supported by the nano potential situation between the nanoshapes in suspension.\u003c/p\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eVarious geometrical nanoshapes and a complicated nanoparticle were suspended in water and allowed to settle on a hydrophilic substrate. Their monolayer arrangement was created following the dilution of the sample in order to analyze their assembly process in suspension due to molecular capping arrangements. It was discovered that surfactant-directed mechanisms, such as the comb-brush effect, play an essential role in inducing shape and size effects at the flat and curved ends of nanoshapes. The brush (radially orientated) effect induced by CTAB molecules surrounding the nanoparticles' curve facets likes to join with the similar facets next to it. On the other hand, the flat geometry of nanoparticles with the comb-like effect caused by surfactant molecules arranges with the adjoining flat surface. This effect dictates the orientation of nanoshapes in suspension. Furthermore, the drying capillaries on the surface will swirl them together with the desired aspects. However, conditions must be met for these nanoshapes to get closer to one another in suspension before molecular interactions may take place. For these particles to be able to attain lower energy, there has to be some sort of attractive potential between them. The Van der Waals potential, which brought these nanoshapes together in suspension, is the most important interaction between them. The instances examined here have shown that attractiveness never goes away and that its effectiveness\u0026mdash;or the depth of the potential well\u0026mdash;increases as its dimensions alter. Nanoparticles' short and long axes significantly affect this potential. Their distinct appealing potential also brought them together with like-minded others. While the thin will be thin, the thick will choose to join with the thicker ones. Similarly, short and long nanoparticles will assemble with short and long shapes. The strong attracting potential in suspension determines the form and size impact. The entropic effect is another crucial metric for closely packed liquid crystalline phases since it demonstrates the free volume effect. The phenomenon is most noticeable in complexed-shaped nanoparticles, where the open spaces between the curving complexed structures exhibit an accumulation of small spheres and other forms. Researchers will be able to estimate and comprehend the shape and size of assemblies with the aid of this work, particularly for achieving monolayer LC phases.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgement:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work is carried out at Department of Physics, University of Peshawar.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaring your interests:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eI have no potential competing or non-financial interests in publishing this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eImtiaz Ahmad: Conceptualization, Visualization, Investigation, Supervision, Original draft preparation, data analysis, expertise in self-assembly, Methodology, Experimental work, Data curation.Rahim Jan: Software, data analysis, Suggestions in work discussion. Hidayat Ullah Khan: Writing- Reviewing and Editing.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eWang, Z. et al. Correlating superlattice polymorphs to inter-nanoparticle distance, packing density and surface lattice in assemblies of PbS nanoparticles. \u003cem\u003eNano Lett.\u003c/em\u003e 13, 1303\u0026ndash;1311 (2013).\u003c/li\u003e\n\u003cli\u003eLi, R. et al. An obtuse rhombohedral superlattice assembled by Pt nanocubes. Nano Lett. 15, 6254\u0026ndash;6260 (2015).\u003c/li\u003e\n\u003cli\u003eChoi, J. J., Bian, K., Baumgardner, W. J., Smilgies, D.-M. \u0026amp; Hanrath, T. Interface-induced nucleation, orientational alignment and symmetry transformations in nanocube superlattices. Nano Lett. 12, 4791\u0026ndash;4798 (2012).\u003c/li\u003e\n\u003cli\u003eBian, K. et al. Shape-anisotropy driven symmetry transformations in nanocrystal superlattice polymorphs. ACS Nano 5, 2815\u0026ndash;2823 (2011).\u003c/li\u003e\n\u003cli\u003eCollier, C. P., Saykally, R. J., Shiang, J. J., Henrichs, S. E. \u0026amp; Heath, J. R. Reversible tuning of silver quantum dot monolayers through the metal-insulator transition. Science 227, 1978\u0026ndash;1981 (1997).\u003c/li\u003e\n\u003cli\u003eBian, K., Wang, Z. \u0026amp; Hanrath, T. Comparing the structural stability of PbS nanocrystals assembled in fcc and bcc superlattice allotropes. J. Am. Chem. Soc. 134, 10787\u0026ndash;10790 (2012).\u003c/li\u003e\n\u003cli\u003eKim, J. et al. Polymorphic assembly from beveled gold triangular nanoprisms. Nano Lett. 17, 3270\u0026ndash;3275 (2017).\u003c/li\u003e\n\u003cli\u003eKim, J., Ou, Z., Jones, M. R., Song, X. \u0026amp; Chen, Q. Imaging the polymerization of multivalent nanoparticles in solution. Nat. Commun. 8, 761 (2017).\u003c/li\u003e\n\u003cli\u003eBishop, K. J. M.; Wilmer, C. E.; Soh, S.; Grzybowski, B. A. Nanoscale Forces and Their Uses in Self-Assembly. Small 2009, 5, 1600\u0026minus;1630.\u003c/li\u003e\n\u003cli\u003eLi, B. et al. Stress-induced phase transformation and optical coupling of silver nanoparticle superlattices into mechanically stable nanowires. Nat. Commun. 5, 4179 (2014).\u003c/li\u003e\n\u003cli\u003eWu, H. et al. Nanostructured gold architectures formed through high pressure-driven sintering of spherical nanoparticle arrays. J. Am. Chem. Soc. 132, 12826\u0026ndash;12828 (2010).\u003c/li\u003e\n\u003cli\u003eKim, J., Ou, Z., Jones, M. R., Song, X. \u0026amp; Chen, Q. Imaging the polymerization of multivalent nanoparticles in solution. Nat. Commun. 8, 761 (2017).\u003c/li\u003e\n\u003cli\u003eE. Roduner, Chem. Soc. Rev. 2006, 35, 583. 10.1039/b502142c\u003c/li\u003e\n\u003cli\u003eHideyuki Mitomo, Kuniharu Ijiro, Controlled Nanostructures Fabricated by the Self-Assembly of Gold Nanoparticles via Simple Surface Modifications, Bulletin of the Chemical Society of Japan, Volume 94, Issue 4, April 2021, Pages 1300\u0026ndash;1310, https://doi.org/10.1246/bcsj.20210031\u003c/li\u003e\n\u003cli\u003eY. Niidome, A. T. Haine, T. Niidome, Chem. Lett. 2016, 45, 488. 10.1246/cl.160124\u003c/li\u003e\n\u003cli\u003eK. Xu, R. Zhou, K. Takei, M. Hong, Adv. Sci. 2019, 6, 1900925. 10.1002/advs.20190092\u003c/li\u003e\n\u003cli\u003eD. Frenkel, Order through entropy. Nat. Mater. 14, 9\u0026ndash;12 (2015).\u003c/li\u003e\n\u003cli\u003eHao, Y.; Fang, L.; Deng, Z. Solvo-Driven Dimeric Nanoplasmon Coupling Under DNA Direction. CCS Chem. 2021, 3, 1359\u0026ndash;1367.\u003c/li\u003e\n\u003cli\u003eWang, P.F.; Huh, J.H.; Lee, J.; Kim, K.; Park, K.J.; Lee, S.; Ke, Y. Magnetic Plasmon Networks Programmed by Molecular Self-Assembly. \u003cem\u003eAdv. Mater.\u003c/em\u003e\u003cstrong\u003e2019\u003c/strong\u003e, \u003cem\u003e31\u003c/em\u003e, 1901364.\u003c/li\u003e\n\u003cli\u003eTanwar, S.; Kaur, V.; Kaur, G.; Sen, T. Broadband SERS Enhancement by DNA Origami Assembled Bimetallic Nanoantennas with Label-Free Single Protein Sensing. J. Phys. Chem. Lett. 2021, 12, 8141\u0026ndash;8150\u003c/li\u003e\n\u003cli\u003eAhmad, I.; Zandvliet, H. J. W.; Kooij, E. S. Langmuir 2014, 30, 7953\u0026ndash;7961. doi:10.1021/la500980j\u003c/li\u003e\n\u003cli\u003eNikoobakht B and El-Sayed M A 2003 Chem. Mater. 15 1957.\u003c/li\u003e\n\u003cli\u003eG. Hlawacek, Imtiaz Ahmad, M. A. Smithers, E. S. Kooij, To see or not to see: imaging surfactant coated nano-particles using HIM and SEM, Ultramicroscopy 135, (2013) 89-94.\u003c/li\u003e\n\u003cli\u003eAhmad, I., \u0026amp; Hussain, A. (2020). Analysis of colloidal nanostructures synthesized through complex route. Inorganic and Nano-Metal Chemistry, 50(12), 1248\u0026ndash;1253. https://doi.org/10.1080/24701556.2020.1745836\u003c/li\u003e\n\u003cli\u003eImtiaz Ahmad, Hidayat Ullah Khan, Rahim Jan, Sajjad Ahmad Khan, Anisotropic gold nanoparticles crystalizes in multifaceted superstructures, Mater. Res. Express 6 (2019) 105006.\u003c/li\u003e\n\u003cli\u003eAhmad, I. Deposition and distribution of gold nanoparticles in a coffee-stain ring on the HOPG terraces. \u003cem\u003eBull Mater Sci\u003c/em\u003e\u003cstrong\u003e43\u003c/strong\u003e, 118 (2020). https://doi.org/10.1007/s12034-020-02094-7\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"LC- phases, Nanocrystals, Assembly, Crystallographic facets, steric interaction","lastPublishedDoi":"10.21203/rs.3.rs-4531195/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4531195/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe yield collective effect that is generated by each member of the LC phase largely depends on a uniform dispersion of nanoparticles. Evaporation techniques have been used to complete several fluidic-assisted designs. We examine isolated arrays of heterogeneous nanoparticles, taking into account the free entropic volume effect, comb- and brush-effect, electrostatic, and Van der Waals effects. The crystallographic facets of suspended particles and capping agents on their surfaces determine the optimal arrangement of shapes and orientations. It has been discovered that self-assembling activities occur prior to substrate deposition in nanoparticles with both flat and curved geometries. The drying capillaries drive the structures to develop into more aligned and tightly packed, making it easier to bring all of their shapes in suspension together due to dominant attractive interactions. We investigated some noteworthy cases that shed light on the quantitative and significant factors that are involved in constructing well-organized systems.\u003c/p\u003e","manuscriptTitle":"Priorities of Nano Geometries in Suspension","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-26 15:27:46","doi":"10.21203/rs.3.rs-4531195/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"643ab7e3-2dd3-4ef0-aa62-3306b20c728f","owner":[],"postedDate":"June 26th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-07-22T22:54:07+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-26 15:27:46","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4531195","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4531195","identity":"rs-4531195","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}