Myrcene based porous polymers via emulsion templating and thiol-ene polymerisation

Myrcene based porous polymers via emulsion templating and thiol-ene polymerisation | 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 Myrcene based porous polymers via emulsion templating and thiol-ene polymerisation Amadeja Koler, Peter Krajnc This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6521580/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 04 Aug, 2025 Read the published version in Monatshefte für Chemie - Chemical Monthly → Version 1 posted 4 You are reading this latest preprint version Abstract Porous polymer networks were synthesized via thiol–ene photopolymerization using a naturally occuring terpene myrcene and the multifunctional thiol, trimethylolpropane tris(3-mercaptopropionate). A highly porous structure (up to 80% porosity) was achieved by polymerizing the monomeric phase of high internal phase (HIP) emulsions, composed of myrcene and trimethylolpropane tris(3-mercaptopropionate) in the presence of ethylene glycol dimethacrylate (EGDMA), which facilitated the formation of polyHIPE materials. Myrcene was incorporated in concentrations ranging from 9 to 40 mol%, and its content was found to significantly influence the resulting polymer morphology. Depending on the formulation, both bicontinuous-like and open-cell polyHIPE morphologies were obtained. In addition to myrcene content, the thiol-to-alkene functional group ratio (1:1 ratio of thiol to alkene groups, as well as formulations with an excess of alkene functionalities relative to thiols). Photochemistry Terpenes Thiol-ene reaction PolyHIPEs Myrcene Figures Figure 1 Introduction This growing reliance on fossil-based chemistry in the production of organic compounds has raised concerns in recent years. This has led to a wave of initiatives aimed at replacing fossil raw materials with renewable ones. Particularly strong efforts are being made in the field of polymer science and technology, where researchers are developing macromolecular materials derived from renewable sources. As natural polymers such as cellulose and poly(hydroxyalkanoates) have long been studied and are widely utilized, nature continues to serve as a valuable source in the search for novel bio-based raw materials for the development of environmentally friendly polymeric materials.[ 1 , 2 ] Recently, many researchers have focused their efforts on identifying and utilizing starting materials derived from renewable resources. In this context, terpene-based monomers obtained from natural sources have attracted increasing attention. Polyisoprene, the main component of natural rubber, has been known for over a century, and other terpenes—such as pinene, limonene, carvone, myrcene, have also been employed in the synthesis of polyolefins.[ 3 , 4 ] The growing interest in terpene-derived monomers has extended to the development of porous polymer architectures, particularly polyHIPE materials.[ 5 – 8 ] PolyHIPEs are highly porous polymers formed by the polymerization of the continuous (monomer) phase of a high internal phase emulsion [ 9 ], typically containing more than 74% internal (dispersed) phase. The resulting materials exhibit a unique open-cell structure with interconnected pores, making them ideal for applications that require high surface area, low density, and tunable porosity. PolyHIPE polymers have been employed across a wide range of fields, including catalysis [ 10 , 11 ], separation membranes[ 12 – 16 ], biomedical scaffolds[ 17 ], sensors[ 18 ] and others. Their highly porous structure enhances mass transport, promotes efficient functionalization of internal surfaces, and provides mechanical stability with minimal material usage. In recent years, bio-based polyHIPEs synthesized from terpene-derived monomers have emerged as a promising class of sustainable materials. For example, monomers derived from limonene, pinene, and myrcene have been successfully used in HIPE formulations to generate porous structures with reduced reliance on fossil-derived chemicals. For the synthesis of polyHIPE materials, α-pinene has been employed for self-crosslinking, enabled by hydrogen abstraction from its pendant group.[ 19 ] Additionally, acrylate monomers were prepared via the reaction of terpenoids—namely tetrahydrogeraniol, citronellol, and nopol—with acryloyl chloride. These newly formed bio-based monomers were subsequently crosslinked using 5–10 mol% of trimethylolpropane triacrylate (TMPTA) as a crosslinker, resulting in highly porous polyHIPE polymers with an open-cell architecture.[ 20 ] Furthermore, polyHIPEs have also been synthesized directly from naturally derived terpenes to replace conventional fossil-based monomers. In this context, hierarchically porous polyHIPEs were prepared from limonene, myrcene, and carvone, using multifunctional acrylates such as pentaerythritol triacrylate (PETA) and TMPTA as crosslinkers.[ 21 ] Similarly, myrcene and limonene were copolymerized with ethylene glycol dimethacrylate (EGDMA), where it was observed that the concentration of the terpene monomers had a significant impact on the resulting pore morphology of the polyHIPE structure.[ 22 ] Myrcene and limonene were used as renewable monomers for the synthesis of the first sustainable adsorbents, prepared via free-radical copolymerization crosslinking within water-in-oil (w/o) high internal phase emulsions (HIPEs). Such polymers have been used successfully for the removal of tetracycline and ibuprofen.[ 23 ] In another approach, limonene-based polyHIPEs were synthesized by crosslinking with EGDMA, utilizing 50 vol.% bio-derived monomer in the HIPE formulation. Palmitic acid was successfully incorporated into the porous network to yield stable composite suitable for passive solar heating applications.[ 24 ] Myrcene has been employed for the direct synthesis of polyHIPE materials, notably through copolymerization with 1,4-butanediol dimethacrylate (BDDMA). In one study, the ratio of myrcene to BDDMA was varied revealing that the myrcene content significantly influenced both emulsion stability and the extent of crosslinking. The resulting materials demonstrated exceptional sorption capacities for organic solvents such as benzene, toluene, and hexane.[ 25 ] In a related approach, myrcene was also photopolymerized with BDDMA, where it was determined that a 60% myrcene content represented the optimal ratio for achieving a highly crosslinked polyHIPE with a desirable open-cellular pore morphology. [ 26 ] Myrcene and BDDMA were also used for copolymerization with 4-vinylbenzyl chloride and divinylbenzene monomers. The resulting polymer was hypercrosslinked by the Friedel-Crafts reaction, thereby increasing the specific surface area of ​​the polymers to 60 m 2 /g.[ 27 ] Terpene-based polyHIPEs were prepared by copolymerizing myrcene with either poly(ethylene glycol) dimethacrylate (PEGDMA) or EGDMA in water-in-oil emulsions. Crosslinker type and content significantly affected the materials' pore structure and mechanical properties.[ 28 ] In all reported cases, the polymerization of terpene-based polyHIPE materials has been conducted via free-radical polymerization. This study focuses on the utilization of thiol-ene polymerization for the synthesis of terpene based polyHIPEs, reporting a novel approach in this field. Thiol-ene polymerization uses a click-type reaction between a thiol and an alkene resulting in a radical initiated step-growth polymerization mechanism.[ 29 ] It is characterized by its high efficiency, regioselectivity, and tolerance to oxygen and moisture. When applied to the preparation of polyHIPE materials[ 30 – 34 ], thiol-ene polymerization offers several advantages over traditional free-radical approaches. These include enhanced structural uniformity, improved mechanical properties, and the potential for lower polymerization-induced stress. Moreover, the modularity of thiol-ene chemistry facilitates the incorporation of a wide variety of functional monomers, allowing for precise tailoring of the material’s chemical and physical properties. Results and Discussion Several initial factors were examined in the development of water-in-oil (w/o) polyHIPEs, with the selection of an appropriate surfactant system being the most important. The hydrophilic-lipophilic balance (HLB) serves as an essential guide for selecting a suitable non-ionic surfactant, where a lower HLB indicates a higher proportion of lipophilic groups in the molecule. For w/o emulsions, surfactants with low HLB values are preferred due to their stronger affinity for the oil phase. In this investigation, Span surfactants, which are non-ionic polysorbate-based surfactants, were chosen for their chemical structure, consisting of hydrophobic alkyl chains (hydrocarbons) and hydrophilic polyethylene glycol (PEG) chains. Specifically, Span 80 (HLB = 4.3) and Span 60 (HLB = 4.7) were selected based on previous experience with w/o high internal phase emulsions. However, stable emulsions could not be formed with all the chosen surfactants. A stable high internal phase emulsion was only successfully obtained with Hypermer B246 (HLB = 4.9), a block copolymer of polyhydroxystearic acid and polyethylene glycol. Therefore, Hypermer B246 was selected for further investigation. Polymeric materials were successfully obtained after polymerization using the appropriate surfactant Hypermer B246 and the photoinitiator phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819), with all samples containing 80 vol.% of aqueous phase. The stability of the emulsion and the final morphology were influenced not only by the selection of the surfactant but also by its concentration. Stable emulsions were formed with 5, 10 and 20 wt.% surfactant based on the total mass of monomers; however, higher concentrations (10 and 20 wt.%) adversely affected the material’s morphology. Therefore, a concentration of 5 wt.% surfactant was used for all subsequent experiments. Additionally, toluene was incorporated into the monomer mixture to dissolve the surfactant. The addition of toluene, even at concentrations up to 40 vol.% relative to the monomer phase, did not affect the stability of the emulsions. However, the presence of toluene had an impact on the shrinkage of the polymeric materials during polymerization and drying. Materials containing higher amounts of toluene exhibited shrinkage that was attributed to the capillary forces during solvent evaporation; as toluene evaporates, capillary stresses increase, potentially leading to the collapse of the structured pores and disruption of the polymer’s primary structure. Therefore, up to 15 vol.% of toluene relative to organic phase was used. Thiol-ene polymerization was used for the polymerization of formed HIPEs. Terpene myrcene was selected as a natural alternative to petroleum-derived monomers, while trimethylolpropane tris(3-mercaptopropionate) (tri-thiol) was used as the thiol component. It was assumed that myrcene possesses two polymerizable double bonds that can participate in polymerization either via free radical polymerization with EGDMA or through thiol-ene polymerization with the tri-thiol. It is known that the polymerization of myrcene predominantly results in the formation of 1,4- and 3,4-units, while the 1,2-unit forms only in a very limited proportion.[ 35 ] Additionally, it is presumed that the double bond present in the 1,2-unit is too sterically hindered to participate in the reaction. Since thiol-ene polymerization follows a step-growth mechanism, the functional groups of the monomers were used in a stoichiometric 1:1 molar ratio (double bonds:thiol groups) to ensure efficient network formation. Additionally, the possibility of conventional free radical polymerization was considered, leading to the use of a higher proportion of alkenes relative to thiols. As a result, a higher molar fraction of double bonds compared to thiol groups was introduced into the system to facilitate the polymerization (sample TT3 and TT5, Table 1 ). Gravimetrically measured yields of prepared samples, regardless of the composition, were over 93%, suggesting full incorporation of monomers. Prior to polymerization, the reactivity of myrcene compared to EGDMA in thiol-ene polymerization was evaluated and, as expected a lower reactivity of myrcene was found. In order to facilitate the overall polymerization, EGDMA was introduced to the polymerization mixture. High polymerization yields indicate that the polymerization proceeded efficiently at the given alkene-to-thiol ratios. Table 1 Compositions of prepared polyHIPEs Sample Molar ratio (Myrcen:EGDMA:tri thiol) [vinyl/SH] TT1 4:4:2 1:1 TT2 2:4:4 1:1 TT3 2:4:6 1,3:1 TT4 1:4:5 1:1 TT5 1:4:6 1,3:1 The polymerization efficiency and, consequently, the successful incorporation of monomers into the polymer were also assessed through elemental analysis (Table 2 ). The theoretical sulfur content in the individual samples was compared with the measured values, and a good agreement was found in all cases. This indicates that the polymerization proceeded successfully when the molar ratio of double bonds to thiol groups was 1:1, as well as when a higher proportion of alkene compared to thiol was used in the polymerization mixture. Table 2 Sulfur elemental analyses Sample Molar ratio (Myrcen:EGDMA:tri thiol) Mol% of myrcene [vinyl/SH] S (found) [ wt. %] S (calculated) [ wt. %] TT1 4:4:2 40 1:1 14,96 15,68 TT2 2:4:4 20 1:1 14,18 14,22 TT3 2:4:6 18 1,3:1 12,36 12,45 TT4 1:4:5 10 1:1 14,02 14,21 TT5 1:4:6 9 1,3:1 12,63 12,94 The morphology of the samples was characterized using scanning electron microscopy (SEM). Five samples (labelled TT1–TT5) were synthesized using different molar ratios of the monomers myrcene, tri-thiol, and EGDMA. The content of myrcene was varied between 9 and 40 mol% (Table 1 ). In addition to varying the myrcene content, the thiol-to-ene molar ratio was also adjusted. In samples TT1, TT2, and TT4, a 1:1 molar ratio of thiol groups to double bonds was used, enabling thiol-ene photopolymerization to occur. In contrast, in samples TT3 and TT5, a higher proportion of double bonds relative to thiol groups was used, leading to the occurrence of both thiol-ene photopolymerization and free-radical polymerization involving myrcene and EGDMA. The same conditions which could influence the emulsion stabilization were applied to all samples, namely 80 vol.% of the aqueous phase, 5 wt.% of Hypermer B246 surfactant relative to the monomer mass, and 15 vol.% of toluene relative to the total volume of the monomer phase. The ratio of monomers were varied (Table 1 ). Therefore, the differencies in formed morphologies can be attributed to the monomer ratio. As shown in Fig. 1 , considerable differences can be observed. In the cases of TT1 and TT2, a bicontinuous-like structure was obtained, with pores on the order of approximately 16 µm (TT1) and 12 µm (TT2) between the polymer domains. In contrast, samples TT3 to TT5 displayed a polyHIPE morphology. TT3 exhibited a more closed-cell structure, while TT4 and TT5 showed primary pores of approximately 36 µm (TT5) and 22 µm (TT4) connected to secondary pores of 4 µm (TT5) and 3 µm (TT4). The differences in the morphologies of these samples are attributed to variations in the myrcene content and the polymerization method employed. The porous structure and morphology of polymers prepared via thiol–ene polymerization of monomer phase of high internal phase emulsions (HIPEs) are influenced by the emulsion phase ratio and the concentration of the surfactant. We have previously found that by varying these parameters, reduced HIPE stability can result in phase inversion and consequently in the formation of interconnected cellular morphology, bicontinuous porous structure, or inverted polymer monolith structure.[ 36 ] In our case, these parameters were kept constant, indicating that the observed structural differences can be attributed solely to the myrcene content or the polymerization pathway. We hypothesize that at higher myrcene concentrations, due to its lower reactivity, polymer network formation favors EGDMA–trithiol or EGDMA–EGDMA linkages over EGDMA–myrcene or myrcene–trithiol, thereby influencing pore architecture. Furthermore, we found that at comparable myrcene contents (10 or 20 mol%), a more well-defined polyHIPE morphology is obtained when free-radical polymerization occurs alongside the thiol–ene reaction. This suggests that myrcene exhibits higher reactivity under free-radical polymerization conditions. Such variations affected the crosslinking mechanism—promoting either a more uniform thiol–ene network or enabling additional radical homopolymerization pathways—both of which significantly impacted the resulting pore size distribution, interconnectivity, and overall structure of the polymer network. Table 3 BET specific surface area and porosity data Sample Molar ratio (Myrcen:EGDMA:tri thiol) [vinyl/SH] Porosity [%]* BET specific surface area [m 2 /g] TT1 4:4:2 1:1 67 4,35 TT2 2:4:4 1:1 69 7,64 TT3 2:4:6 1,3:1 78 7,99 TT4 1:4:5 1:1 74 5,16 TT5 1:4:6 1,3:1 81 8,25 *measured by pycnometry Using solid densiometry, a comparison between the theoretical (as prepared HIPE) and measured porosity was made. The theoretically calculated porosity was 80% in all samples. In contrast, samples TT1 and TT2 showed a slight deviation from the theoretical value; however, the porosity in these cases still exceeded 67% (Table 3 ). The BET specific surface areas were determined by nitrogen adsorption/desorption using the BET method and were found to be relatively low, ranging between 5 and 8 m²/g suggesting the formation of mostly macro pores (Table 3 ). Conclusion We have shown that a monomer from renewable source, namely myrcene, can be included in porous polymers prepared using a thiol-ene polymerization mechanism and high internal phase emulsion templating thus producing a terpene based highly porous polymer material in an efficient manner. The emulsion-templated approach enabled the formation of highly porous structures, with porosities reaching up to 80%. By varying the molar ratio of monomers and adjusting the ratio of thiol to alkene functional groups, it is demonstrated that both parameters have a significant impact on the final morphology of the polymer monoliths. At lower myrcene contents (10 mol %) and with a higher proportion of thiol relative to alkene groups, well-defined polyHIPE morphologies with interconnected cellular pores were obtained, while higher myrcene contents and changes in the thiol-to-alkene ratio 1:1 promoted the formation of bicontinuous porous structures, suggesting the occurence of meta stability and phase inversion of the emulsion. The study demonstrates the potential of using renewable monomers like myrcene in the fabrication of sustainable, tunable porous polymer networks. The ability to modulate morphology through simple formulation parameters opens new opportunities for designing advanced materials. Experimental Materials and methods Monomers myrcene (Sigma Aldrich, technical grade), trimethylolpropane tris(3-mercaptopropionate) (trithiol, Sigma Aldrich, ≥95%), and ethylene glycol dimethacrylate (EGDMA, Sigma Aldrich, 98%) were purified by passing through a column of aluminum oxide to remove the inhibitors. Hypermer B246 (Croda), Irgacure 819 (I-819, BASF), toluene (Sigma Aldrich), ethanol (Sigma Aldrich), and calcium chloride hexahydrate (CaCl₂·6H₂O, 98%, Sigma Aldrich) were used as received. Preparation of polymer monoliths For the preparation of the high internal phase (HIP) emulsion, the organic phase was first prepared in a two-necked darkened amber glass flask. Monomers—myrcene, ethylene glycol dimethacrylate (EGDMA), and trimethylolpropane tris(3-mercaptopropionate) (trithiol)—were weighed into the flask in various molar ratios, along with the surfactant Hypermer B246, toluene, and the photoinitiator Irgacure 819 (based on the total mass of monomers), as specified in Table 4. The flask was then mounted on an overhead stirrer and mixed for approximately 10 minutes to ensure thorough homogenization of the organic phase. Separately, the aqueous phase was prepared using calcium chloride hexahydrate dissolved in degassed distilled water to obtain a 1.76% solution. The appropriate volume of the aqueous phase (corresponding to 80 vol.% of the total emulsion volume) was transferred into a dropping funnel and added dropwise to the organic phase under continuous stirring. Once the entire aqueous phase had been added, stirring was continued for additional 30 minutes. After emulsification, the mixture was cast into silicone molds and cured in a UV chamber (Intelliray 600, Uvitron) for 120 seconds at 80% light intensity (distance from the light source: 130 mm; irradiance: 120 mW/cm²). After polymerization, the resulting polymer monoliths were purified using Soxhlet extraction with ethanol for 24 hours and subsequently dried in air to a constant weight. The samples were labeled as TTx (where "TT" denotes T erpene– T hiol and "x" corresponds to the sample number). Table 4: Composition of samples TT1-TT5 Sample m(myrcene) [g] m(tri-thiol) [g] m(EGDMA) [g] V (water phase) [cm 3 ] V (toluene) [cm 3 ] m(Hypermer) [g] m(Irgacure 819) [g] TT1 0.543 1.747 0.394 7.5 0.5 0.322 0.075 TT2 0.322 1.695 0.855 6.4 0.5 0.428 0.131 TT3 0.277 1.574 1.194 5.5 0.5 0.525 0.065 TT4 0.334 1.790 0.800 7.0 0.5 0.358 0.135 TT5 0.343 1.800 0.620 6.6 0.5 0.413 0.113 Characterisation Scanning electron microscopy (SEM) was performed using a Philips XL-30 microscope operated at an accelerating voltage of 20 kV. Prior to imaging, the samples were sputter-coated with gold using a Q150R Quorum ion sputter coater for 240 seconds at a current of 70 mA. Porosity was measured using a Micromeritics GeoPyc 1360 instrument and were carried out using a 12.7 mm sample cell and piston assembly. The efficiency of the polymerization was evaluated using a PerkinElmer CHNS/O 2400 Series II elemental analyzer by comparing the experimentally determined sulfur content with the theoretical values calculated for each polymer composition. The specific surface area of the samples was determined using a Micromeritics TriStar II 3020 analyzer at 77.4 K. Measurements were performed by nitrogen adsorption/desorption, and the specific surface area was calculated using the Brunauer–Emmett–Teller (BET) method. Prior to analysis, all samples were degassed under a nitrogen flow at 40 °C for 24 hours. Declarations Conflict of interest statement The authors declare no conflict of interest in connection with the manuscript. Acknowledgements Financial support of the Slovenian Research Agency (ARIS) through grant P2-0006 is gratefully acknowledged. References S. Rajendran, A. Al-Samydai, G. Palani, H. Trilaksana, T. Sathish, J. Giri, J. I. J. R. Lalvani, and F. Nasri (2025) Eng. Reports 7:70108. P. 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Liu, A. M. Eissa, and D. M. Haddleton (2022) ACS Sustain. Chem. Eng. 10:9654. V. Hobiger, M. Paljevac, and P. Krajnc (2022) Polymers 14:1. Cite Share Download PDF Status: Published Journal Publication published 04 Aug, 2025 Read the published version in Monatshefte für Chemie - Chemical Monthly → Version 1 posted Reviewers agreed at journal 06 May, 2025 Reviewers invited by journal 30 Apr, 2025 Editor assigned by journal 29 Apr, 2025 First submitted to journal 26 Apr, 2025 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. 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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-6521580","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":450070627,"identity":"f48f596a-6363-485b-8adc-e91a5bdb4d61","order_by":0,"name":"Amadeja Koler","email":"","orcid":"","institution":"Univerza v Mariboru","correspondingAuthor":false,"prefix":"","firstName":"Amadeja","middleName":"","lastName":"Koler","suffix":""},{"id":450070628,"identity":"5c51c78f-8007-4da6-b93b-3770b9d7e972","order_by":1,"name":"Peter Krajnc","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0ElEQVRIiWNgGAWjYPCCBCA+wMDwAcRmJqiaGaGFcQaJWoBMHmJcZM7ef/BxBUNaPn/j2YOfbdu2Mci3E9Bi2XOY2fAMQ47ljAPnkqVz224zGBwmoMXgRjKbZANDhQHDgTNmzGAthPxicP8x+0+QFnmQFkugFvlmgrYwszE2MOQYGIC0MAK1MBBymGVPsrFkg0GageGBM8aSPedu8xD0izn7wYcfGyqSDeRunDH88KPstpx8/wECDoOTEhCVhKPGAM7ibyCoeBSMglEwCkYoAAD9gD/N+3hEawAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-9782-131X","institution":"Univerza v Mariboru","correspondingAuthor":true,"prefix":"","firstName":"Peter","middleName":"","lastName":"Krajnc","suffix":""}],"badges":[],"createdAt":"2025-04-24 14:16:39","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6521580/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6521580/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00706-025-03360-2","type":"published","date":"2025-08-04T15:56:50+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":82049224,"identity":"bde21872-2b19-430e-9a7a-44b236eafbb7","added_by":"auto","created_at":"2025-05-06 09:50:59","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":796203,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images for samples TT1-TT5\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6521580/v1/b8bb0122a1bb141676e9f926.png"},{"id":88814062,"identity":"1dda0658-9eed-4e23-9edd-7f83ca5212dd","added_by":"auto","created_at":"2025-08-11 16:04:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1576300,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6521580/v1/2c507969-4336-4521-ad26-59d410f9e8b1.pdf"}],"financialInterests":"","formattedTitle":"Myrcene based porous polymers via emulsion templating and thiol-ene polymerisation","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThis growing reliance on fossil-based chemistry in the production of organic compounds has raised concerns in recent years. This has led to a wave of initiatives aimed at replacing fossil raw materials with renewable ones. Particularly strong efforts are being made in the field of polymer science and technology, where researchers are developing macromolecular materials derived from renewable sources. As natural polymers such as cellulose and poly(hydroxyalkanoates) have long been studied and are widely utilized, nature continues to serve as a valuable source in the search for novel bio-based raw materials for the development of environmentally friendly polymeric materials.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] Recently, many researchers have focused their efforts on identifying and utilizing starting materials derived from renewable resources. In this context, terpene-based monomers obtained from natural sources have attracted increasing attention. Polyisoprene, the main component of natural rubber, has been known for over a century, and other terpenes\u0026mdash;such as pinene, limonene, carvone, myrcene, have also been employed in the synthesis of polyolefins.[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThe growing interest in terpene-derived monomers has extended to the development of porous polymer architectures, particularly polyHIPE materials.[\u003cspan additionalcitationids=\"CR6 CR7\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] PolyHIPEs are highly porous polymers formed by the polymerization of the continuous (monomer) phase of a high internal phase emulsion [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], typically containing more than 74% internal (dispersed) phase. The resulting materials exhibit a unique open-cell structure with interconnected pores, making them ideal for applications that require high surface area, low density, and tunable porosity.\u003c/p\u003e \u003cp\u003ePolyHIPE polymers have been employed across a wide range of fields, including catalysis [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], separation membranes[\u003cspan additionalcitationids=\"CR13 CR14 CR15\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], biomedical scaffolds[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], sensors[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] and others. Their highly porous structure enhances mass transport, promotes efficient functionalization of internal surfaces, and provides mechanical stability with minimal material usage.\u003c/p\u003e \u003cp\u003eIn recent years, bio-based polyHIPEs synthesized from terpene-derived monomers have emerged as a promising class of sustainable materials.\u003c/p\u003e \u003cp\u003eFor example, monomers derived from limonene, pinene, and myrcene have been successfully used in HIPE formulations to generate porous structures with reduced reliance on fossil-derived chemicals. For the synthesis of polyHIPE materials, α-pinene has been employed for self-crosslinking, enabled by hydrogen abstraction from its pendant group.[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] Additionally, acrylate monomers were prepared via the reaction of terpenoids\u0026mdash;namely tetrahydrogeraniol, citronellol, and nopol\u0026mdash;with acryloyl chloride. These newly formed bio-based monomers were subsequently crosslinked using 5\u0026ndash;10 mol% of trimethylolpropane triacrylate (TMPTA) as a crosslinker, resulting in highly porous polyHIPE polymers with an open-cell architecture.[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eFurthermore, polyHIPEs have also been synthesized directly from naturally derived terpenes to replace conventional fossil-based monomers. In this context, hierarchically porous polyHIPEs were prepared from limonene, myrcene, and carvone, using multifunctional acrylates such as pentaerythritol triacrylate (PETA) and TMPTA as crosslinkers.[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] Similarly, myrcene and limonene were copolymerized with ethylene glycol dimethacrylate (EGDMA), where it was observed that the concentration of the terpene monomers had a significant impact on the resulting pore morphology of the polyHIPE structure.[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] Myrcene and limonene were used as renewable monomers for the synthesis of the first sustainable adsorbents, prepared via free-radical copolymerization crosslinking within water-in-oil (w/o) high internal phase emulsions (HIPEs). Such polymers have been used successfully for the removal of tetracycline and ibuprofen.[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn another approach, limonene-based polyHIPEs were synthesized by crosslinking with EGDMA, utilizing 50 vol.% bio-derived monomer in the HIPE formulation. Palmitic acid was successfully incorporated into the porous network to yield stable composite suitable for passive solar heating applications.[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eMyrcene has been employed for the direct synthesis of polyHIPE materials, notably through copolymerization with 1,4-butanediol dimethacrylate (BDDMA). In one study, the ratio of myrcene to BDDMA was varied revealing that the myrcene content significantly influenced both emulsion stability and the extent of crosslinking. The resulting materials demonstrated exceptional sorption capacities for organic solvents such as benzene, toluene, and hexane.[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn a related approach, myrcene was also photopolymerized with BDDMA, where it was determined that a 60% myrcene content represented the optimal ratio for achieving a highly crosslinked polyHIPE with a desirable open-cellular pore morphology. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] Myrcene and BDDMA were also used for copolymerization with 4-vinylbenzyl chloride and divinylbenzene monomers. The resulting polymer was hypercrosslinked by the Friedel-Crafts reaction, thereby increasing the specific surface area of ​​the polymers to 60 m\u003csup\u003e2\u003c/sup\u003e/g.[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eTerpene-based polyHIPEs were prepared by copolymerizing myrcene with either poly(ethylene glycol) dimethacrylate (PEGDMA) or EGDMA in water-in-oil emulsions. Crosslinker type and content significantly affected the materials' pore structure and mechanical properties.[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eIn all reported cases, the polymerization of terpene-based polyHIPE materials has been conducted via free-radical polymerization. This study focuses on the utilization of thiol-ene polymerization for the synthesis of terpene based polyHIPEs, reporting a novel approach in this field. Thiol-ene polymerization uses a click-type reaction between a thiol and an alkene resulting in a radical initiated step-growth polymerization mechanism.[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] It is characterized by its high efficiency, regioselectivity, and tolerance to oxygen and moisture. When applied to the preparation of polyHIPE materials[\u003cspan additionalcitationids=\"CR31 CR32 CR33\" citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e], thiol-ene polymerization offers several advantages over traditional free-radical approaches. These include enhanced structural uniformity, improved mechanical properties, and the potential for lower polymerization-induced stress. Moreover, the modularity of thiol-ene chemistry facilitates the incorporation of a wide variety of functional monomers, allowing for precise tailoring of the material\u0026rsquo;s chemical and physical properties.\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eSeveral initial factors were examined in the development of water-in-oil (w/o) polyHIPEs, with the selection of an appropriate surfactant system being the most important. The hydrophilic-lipophilic balance (HLB) serves as an essential guide for selecting a suitable non-ionic surfactant, where a lower HLB indicates a higher proportion of lipophilic groups in the molecule. For w/o emulsions, surfactants with low HLB values are preferred due to their stronger affinity for the oil phase. In this investigation, Span surfactants, which are non-ionic polysorbate-based surfactants, were chosen for their chemical structure, consisting of hydrophobic alkyl chains (hydrocarbons) and hydrophilic polyethylene glycol (PEG) chains. Specifically, Span 80 (HLB\u0026thinsp;=\u0026thinsp;4.3) and Span 60 (HLB\u0026thinsp;=\u0026thinsp;4.7) were selected based on previous experience with w/o high internal phase emulsions. However, stable emulsions could not be formed with all the chosen surfactants. A stable high internal phase emulsion was only successfully obtained with Hypermer B246 (HLB\u0026thinsp;=\u0026thinsp;4.9), a block copolymer of polyhydroxystearic acid and polyethylene glycol. Therefore, Hypermer B246 was selected for further investigation.\u003c/p\u003e \u003cp\u003ePolymeric materials were successfully obtained after polymerization using the appropriate surfactant Hypermer B246 and the photoinitiator phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (Irgacure 819), with all samples containing 80 vol.% of aqueous phase. The stability of the emulsion and the final morphology were influenced not only by the selection of the surfactant but also by its concentration. Stable emulsions were formed with 5, 10 and 20 wt.% surfactant based on the total mass of monomers; however, higher concentrations (10 and 20 wt.%) adversely affected the material\u0026rsquo;s morphology. Therefore, a concentration of 5 wt.% surfactant was used for all subsequent experiments. Additionally, toluene was incorporated into the monomer mixture to dissolve the surfactant. The addition of toluene, even at concentrations up to 40 vol.% relative to the monomer phase, did not affect the stability of the emulsions. However, the presence of toluene had an impact on the shrinkage of the polymeric materials during polymerization and drying. Materials containing higher amounts of toluene exhibited shrinkage that was attributed to the capillary forces during solvent evaporation; as toluene evaporates, capillary stresses increase, potentially leading to the collapse of the structured pores and disruption of the polymer\u0026rsquo;s primary structure. Therefore, up to 15 vol.% of toluene relative to organic phase was used.\u003c/p\u003e \u003cp\u003eThiol-ene polymerization was used for the polymerization of formed HIPEs. Terpene myrcene was selected as a natural alternative to petroleum-derived monomers, while trimethylolpropane tris(3-mercaptopropionate) (tri-thiol) was used as the thiol component.\u003c/p\u003e \u003cp\u003eIt was assumed that myrcene possesses two polymerizable double bonds that can participate in polymerization either via free radical polymerization with EGDMA or through thiol-ene polymerization with the tri-thiol. It is known that the polymerization of myrcene predominantly results in the formation of 1,4- and 3,4-units, while the 1,2-unit forms only in a very limited proportion.[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e] Additionally, it is presumed that the double bond present in the 1,2-unit is too sterically hindered to participate in the reaction. Since thiol-ene polymerization follows a step-growth mechanism, the functional groups of the monomers were used in a stoichiometric 1:1 molar ratio (double bonds:thiol groups) to ensure efficient network formation. Additionally, the possibility of conventional free radical polymerization was considered, leading to the use of a higher proportion of alkenes relative to thiols. As a result, a higher molar fraction of double bonds compared to thiol groups was introduced into the system to facilitate the polymerization (sample TT3 and TT5, Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eGravimetrically measured yields of prepared samples, regardless of the composition, were over 93%, suggesting full incorporation of monomers. Prior to polymerization, the reactivity of myrcene compared to EGDMA in thiol-ene polymerization was evaluated and, as expected a lower reactivity of myrcene was found. In order to facilitate the overall polymerization, EGDMA was introduced to the polymerization mixture. High polymerization yields indicate that the polymerization proceeded efficiently at the given alkene-to-thiol ratios.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCompositions of prepared polyHIPEs\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMolar ratio (Myrcen:EGDMA:tri thiol)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[vinyl/SH]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4:4:2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2:4:4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2:4:6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1,3:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1:4:5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1:4:6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1,3:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe polymerization efficiency and, consequently, the successful incorporation of monomers into the polymer were also assessed through elemental analysis (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The theoretical sulfur content in the individual samples was compared with the measured values, and a good agreement was found in all cases. This indicates that the polymerization proceeded successfully when the molar ratio of double bonds to thiol groups was 1:1, as well as when a higher proportion of alkene compared to thiol was used in the polymerization mixture.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSulfur elemental analyses\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMolar ratio (Myrcen:EGDMA:tri thiol)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMol% of myrcene\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e[vinyl/SH]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS \u003csub\u003e(found)\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e[\u003cem\u003ewt.\u003c/em\u003e%]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eS \u003csub\u003e(calculated)\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e[\u003cem\u003ewt.\u003c/em\u003e%]\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4:4:2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e14,96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e15,68\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2:4:4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e14,18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e14,22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2:4:6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1,3:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e12,36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e12,45\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1:4:5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e14,02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e14,21\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1:4:6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1,3:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e12,63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e12,94\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe morphology of the samples was characterized using scanning electron microscopy (SEM). Five samples (labelled TT1\u0026ndash;TT5) were synthesized using different molar ratios of the monomers myrcene, tri-thiol, and EGDMA. The content of myrcene was varied between 9 and 40 mol% (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). In addition to varying the myrcene content, the thiol-to-ene molar ratio was also adjusted. In samples TT1, TT2, and TT4, a 1:1 molar ratio of thiol groups to double bonds was used, enabling thiol-ene photopolymerization to occur. In contrast, in samples TT3 and TT5, a higher proportion of double bonds relative to thiol groups was used, leading to the occurrence of both thiol-ene photopolymerization and free-radical polymerization involving myrcene and EGDMA.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe same conditions which could influence the emulsion stabilization were applied to all samples, namely 80 vol.% of the aqueous phase, 5 wt.% of Hypermer B246 surfactant relative to the monomer mass, and 15 vol.% of toluene relative to the total volume of the monomer phase. The ratio of monomers were varied (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Therefore, the differencies in formed morphologies can be attributed to the monomer ratio. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, considerable differences can be observed. In the cases of TT1 and TT2, a bicontinuous-like structure was obtained, with pores on the order of approximately 16 \u0026micro;m (TT1) and 12 \u0026micro;m (TT2) between the polymer domains. In contrast, samples TT3 to TT5 displayed a polyHIPE morphology. TT3 exhibited a more closed-cell structure, while TT4 and TT5 showed primary pores of approximately 36 \u0026micro;m (TT5) and 22 \u0026micro;m (TT4) connected to secondary pores of 4 \u0026micro;m (TT5) and 3 \u0026micro;m (TT4). The differences in the morphologies of these samples are attributed to variations in the myrcene content and the polymerization method employed. The porous structure and morphology of polymers prepared via thiol\u0026ndash;ene polymerization of monomer phase of high internal phase emulsions (HIPEs) are influenced by the emulsion phase ratio and the concentration of the surfactant. We have previously found that by varying these parameters, reduced HIPE stability can result in phase inversion and consequently in the formation of interconnected cellular morphology, bicontinuous porous structure, or inverted polymer monolith structure.[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e] In our case, these parameters were kept constant, indicating that the observed structural differences can be attributed solely to the myrcene content or the polymerization pathway. We hypothesize that at higher myrcene concentrations, due to its lower reactivity, polymer network formation favors EGDMA\u0026ndash;trithiol or EGDMA\u0026ndash;EGDMA linkages over EGDMA\u0026ndash;myrcene or myrcene\u0026ndash;trithiol, thereby influencing pore architecture. Furthermore, we found that at comparable myrcene contents (10 or 20 mol%), a more well-defined polyHIPE morphology is obtained when free-radical polymerization occurs alongside the thiol\u0026ndash;ene reaction. This suggests that myrcene exhibits higher reactivity under free-radical polymerization conditions.\u003c/p\u003e \u003cp\u003eSuch variations affected the crosslinking mechanism\u0026mdash;promoting either a more uniform thiol\u0026ndash;ene network or enabling additional radical homopolymerization pathways\u0026mdash;both of which significantly impacted the resulting pore size distribution, interconnectivity, and overall structure of the polymer network.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBET specific surface area and porosity data\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMolar ratio (Myrcen:EGDMA:tri thiol)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[vinyl/SH]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePorosity [%]*\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBET specific surface area [m\u003csup\u003e2\u003c/sup\u003e/g]\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4:4:2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4,35\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2:4:4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7,64\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2:4:6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1,3:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7,99\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1:4:5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5,16\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTT5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1:4:6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1,3:1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8,25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*measured by pycnometry\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eUsing solid densiometry, a comparison between the theoretical (as prepared HIPE) and measured porosity was made. The theoretically calculated porosity was 80% in all samples. In contrast, samples TT1 and TT2 showed a slight deviation from the theoretical value; however, the porosity in these cases still exceeded 67% (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The BET specific surface areas were determined by nitrogen adsorption/desorption using the BET method and were found to be relatively low, ranging between 5 and 8 m\u0026sup2;/g suggesting the formation of mostly macro pores (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eWe have shown that a monomer from renewable source, namely myrcene, can be included in porous polymers prepared using a thiol-ene polymerization mechanism and high internal phase emulsion templating thus producing a terpene based highly porous polymer material in an efficient manner. The emulsion-templated approach enabled the formation of highly porous structures, with porosities reaching up to 80%. By varying the molar ratio of monomers and adjusting the ratio of thiol to alkene functional groups, it is demonstrated that both parameters have a significant impact on the final morphology of the polymer monoliths. At lower myrcene contents (10 mol %) and with a higher proportion of thiol relative to alkene groups, well-defined polyHIPE morphologies with interconnected cellular pores were obtained, while higher myrcene contents and changes in the thiol-to-alkene ratio 1:1 promoted the formation of bicontinuous porous structures, suggesting the occurence of meta stability and phase inversion of the emulsion. The study demonstrates the potential of using renewable monomers like myrcene in the fabrication of sustainable, tunable porous polymer networks. The ability to modulate morphology through simple formulation parameters opens new opportunities for designing advanced materials.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cp\u003e\u003cstrong\u003eMaterials and methods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMonomers myrcene (Sigma Aldrich, technical grade), trimethylolpropane tris(3-mercaptopropionate) (trithiol, Sigma Aldrich, \u0026ge;95%), and ethylene glycol dimethacrylate (EGDMA, Sigma Aldrich, 98%) were purified by passing through a column of aluminum oxide to remove the inhibitors. Hypermer B246 (Croda), Irgacure 819 (I-819, BASF), toluene (Sigma Aldrich), ethanol (Sigma Aldrich), and calcium chloride hexahydrate (CaCl₂\u0026middot;6H₂O, 98%, Sigma Aldrich) were used as received.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreparation of polymer monoliths\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor the preparation of the high internal phase (HIP) emulsion, the organic phase was first prepared in a two-necked darkened amber glass flask. Monomers\u0026mdash;myrcene, ethylene glycol dimethacrylate (EGDMA), and trimethylolpropane tris(3-mercaptopropionate) (trithiol)\u0026mdash;were weighed into the flask in various molar ratios, along with the surfactant Hypermer B246, toluene, and the photoinitiator Irgacure 819 (based on the total mass of monomers), as specified in Table 4. The flask was then mounted on an overhead stirrer and mixed for approximately 10 minutes to ensure thorough homogenization of the organic phase.\u003c/p\u003e\n\u003cp\u003eSeparately, the aqueous phase was prepared using calcium chloride hexahydrate dissolved in degassed distilled water to obtain a 1.76% solution. The appropriate volume of the aqueous phase (corresponding to 80 vol.% of the total emulsion volume) was transferred into a dropping funnel and added dropwise to the organic phase under continuous stirring. Once the entire aqueous phase had been added, stirring was continued for additional 30 minutes.\u003c/p\u003e\n\u003cp\u003eAfter emulsification, the mixture was cast into silicone molds and cured in a UV chamber (Intelliray 600, Uvitron) for 120 seconds at 80% light intensity (distance from the light source: 130 mm; irradiance: 120 mW/cm\u0026sup2;). After polymerization, the resulting polymer monoliths were purified using Soxhlet extraction with ethanol for 24 hours and subsequently dried in air to a constant weight. The samples were labeled as TTx (where \u0026quot;TT\u0026quot; denotes\u0026nbsp;\u003cstrong\u003eT\u003c/strong\u003eerpene\u0026ndash;\u003cstrong\u003eT\u003c/strong\u003ehiol and \u0026quot;x\u0026quot; corresponds to the sample number).\u003c/p\u003e\n\u003cp\u003eTable 4: Composition of samples TT1-TT5\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSample\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003e\u003cstrong\u003em(myrcene) [g]\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e\u003cstrong\u003em(tri-thiol) [g]\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003em(EGDMA) [g]\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV\u003csub\u003e(water phase)\u0026nbsp;\u003c/sub\u003e[cm\u003csup\u003e3\u003c/sup\u003e]\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eV\u003csub\u003e(toluene)\u0026nbsp;\u003c/sub\u003e[cm\u003csup\u003e3\u003c/sup\u003e]\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003em(Hypermer) [g]\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e\u003cstrong\u003em(Irgacure 819) [g]\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTT1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003e0.543\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e1.747\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 89px;\"\u003e\n \u003cp\u003e0.394\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e7.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.322\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e0.075\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTT2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003e0.322\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e1.695\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 89px;\"\u003e\n \u003cp\u003e0.855\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e6.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.428\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e0.131\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTT3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003e0.277\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e1.574\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 89px;\"\u003e\n \u003cp\u003e1.194\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e5.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.525\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e0.065\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTT4\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003e0.334\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e1.790\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 89px;\"\u003e\n \u003cp\u003e0.800\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e7.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.358\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e0.135\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTT5\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 86px;\"\u003e\n \u003cp\u003e0.343\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e1.800\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 89px;\"\u003e\n \u003cp\u003e0.620\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 61px;\"\u003e\n \u003cp\u003e6.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 66px;\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 95px;\"\u003e\n \u003cp\u003e0.413\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 79px;\"\u003e\n \u003cp\u003e0.113\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eCharacterisation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eScanning electron microscopy (SEM) was performed using a Philips XL-30 microscope operated at an accelerating voltage of 20 kV. Prior to imaging, the samples were sputter-coated with gold using a Q150R Quorum ion sputter coater for 240 seconds at a current of 70 mA. Porosity was measured using a Micromeritics GeoPyc 1360 instrument and were carried out using a 12.7 mm sample cell and piston assembly.\u003c/p\u003e\n\u003cp\u003eThe efficiency of the polymerization was evaluated using a PerkinElmer CHNS/O 2400 Series II elemental analyzer by comparing the experimentally determined sulfur content with the theoretical values calculated for each polymer composition. The specific surface area of the samples was determined using a Micromeritics TriStar II 3020 analyzer at 77.4 K. Measurements were performed by nitrogen adsorption/desorption, and the specific surface area was calculated using the Brunauer\u0026ndash;Emmett\u0026ndash;Teller (BET) method. Prior to analysis, all samples were degassed under a nitrogen flow at 40 \u0026deg;C for 24 hours.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of interest statement\u003c/h2\u003e \u003cp\u003eThe authors declare no conflict of interest in connection with the manuscript.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eFinancial support of the Slovenian Research Agency (ARIS) through grant P2-0006 is gratefully acknowledged.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eS. Rajendran, A. Al-Samydai, G. Palani, H. Trilaksana, T. Sathish, J. Giri, J. I. J. R. Lalvani, and F. Nasri (2025) Eng. Reports 7:70108.\u003c/li\u003e\n\u003cli\u003eP. A. Wilbon, F. Chu, and C. Tang (2013) Macromol. Rapid Commun. 34:8.\u003c/li\u003e\n\u003cli\u003eF. Della Monica and A. W. Kleij (2020) Polym. Chem. 11:5109.\u003c/li\u003e\n\u003cli\u003eP. Sahu, A. K. Bhowmick, and G. 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Eng. 10:9654.\u003c/li\u003e\n\u003cli\u003eV. Hobiger, M. Paljevac, and P. Krajnc (2022) Polymers 14:1.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"monatshefte-fur-chemie-chemical-monthly","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mccm","sideBox":"Learn more about [Monatshefte für Chemie - Chemical Monthly](https://www.springer.com/journal/706)","snPcode":"706","submissionUrl":"https://www.editorialmanager.com/mccm/","title":"Monatshefte für Chemie - Chemical Monthly","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Photochemistry, Terpenes, Thiol-ene reaction, PolyHIPEs, Myrcene","lastPublishedDoi":"10.21203/rs.3.rs-6521580/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6521580/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePorous polymer networks were synthesized via thiol\u0026ndash;ene photopolymerization using a naturally occuring terpene myrcene and the multifunctional thiol, trimethylolpropane tris(3-mercaptopropionate). A highly porous structure (up to 80% porosity) was achieved by polymerizing the monomeric phase of high internal phase (HIP) emulsions, composed of myrcene and trimethylolpropane tris(3-mercaptopropionate) in the presence of ethylene glycol dimethacrylate (EGDMA), which facilitated the formation of polyHIPE materials. Myrcene was incorporated in concentrations ranging from 9 to 40 mol%, and its content was found to significantly influence the resulting polymer morphology. Depending on the formulation, both bicontinuous-like and open-cell polyHIPE morphologies were obtained. In addition to myrcene content, the thiol-to-alkene functional group ratio (1:1 ratio of thiol to alkene groups, as well as formulations with an excess of alkene functionalities relative to thiols).\u003c/p\u003e","manuscriptTitle":"Myrcene based porous polymers via emulsion templating and thiol-ene polymerisation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-06 09:50:55","doi":"10.21203/rs.3.rs-6521580/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-05-06T12:37:45+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-04-30T08:03:18+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-04-29T11:07:42+00:00","index":"","fulltext":""},{"type":"submitted","content":"Monatshefte für Chemie - Chemical Monthly","date":"2025-04-26T15:44:43+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"monatshefte-fur-chemie-chemical-monthly","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mccm","sideBox":"Learn more about [Monatshefte für Chemie - Chemical Monthly](https://www.springer.com/journal/706)","snPcode":"706","submissionUrl":"https://www.editorialmanager.com/mccm/","title":"Monatshefte für Chemie - Chemical Monthly","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"747abece-3036-4feb-b8f8-fada988f9f46","owner":[],"postedDate":"May 6th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-08-11T15:58:51+00:00","versionOfRecord":{"articleIdentity":"rs-6521580","link":"https://doi.org/10.1007/s00706-025-03360-2","journal":{"identity":"monatshefte-fur-chemie-chemical-monthly","isVorOnly":false,"title":"Monatshefte für Chemie - Chemical Monthly"},"publishedOn":"2025-08-04 15:56:50","publishedOnDateReadable":"August 4th, 2025"},"versionCreatedAt":"2025-05-06 09:50:55","video":"","vorDoi":"10.1007/s00706-025-03360-2","vorDoiUrl":"https://doi.org/10.1007/s00706-025-03360-2","workflowStages":[]},"version":"v1","identity":"rs-6521580","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6521580","identity":"rs-6521580","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}