Novel transparent poly(arylene ether nitrile) copolymers with pendant aliphatic ring: synthesis and characterization

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The inherent viscosities of these two copolymers were 0.455 and 0.576 dL g − 1 . The copolymers P-HFD and P-PFD exhibited good thermal property, the glass transition temperatures (T g ) were 202.2-214.9 o C, and the weight-loss temperatures (T 5% ) were 421.3-433.5°C. The polymers’ films had good tensile strengths of 27.3–38.6 MPa. The result of dissolution experiment showed that the copolymers could be dissolved in some solutions at room temperature, such as NMP, DMF and CH 2 Cl 2 , implying that they had good solubility, they can be processed by the solution method. Additionally, the optical transmittances of these two copolymers were 68.3–76.3% at 450 nm, indicating that they have potential to be applied as the heat-resistant optical films. poly(arylene ether nitrile) copolymers synthesis thermal property optical transmittance Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction Transparent polymers refer to a class of polymers with good transparency and physical property. The transparent polymers are mainly divided to aliphatic transparent polymers and aromatic polymers. Comparing with aliphatic transparent polymers (poly(methyl methacrylate) (PMMA) [ 1 – 2 ] , transparent polyamide 1012 [ 3 ] , polyethylene (PE [ 4 ] ), polyvinyl alcohol (PVA) [ 5 ] etc), aromatic transparent polymers (transparent polyethylene terephthalate (PET) [ 6 ] , polyimide [ 7 ] , semi-aromatic polyamide [ 8 ] , etc) have better thermal resistance, mechanical property, radiation resistance, flame-retardant property, etc. This makes them be widely applied in mechanical load-bearing components, high-temperature resistance, radiation resistance fields and so on. Aromatic polymers, such as poly(ether ether ketone) (PEEK) [ 9 ] , poly(ether ether mide) (PEEA) [ 10 ] , poly(arylene ether nitrile) (PEN) [ 11 ] , thermotropic liquid crystal polymer (TLCP) [ 12 ] , etc, have good chain regularity and crystallinity, which endow them with high melting points, thermodynamic property, corrosion resistance, etc. While the high crystallinity reduces their light transmittances, thereby affecting their special applications in the fields of information electronics, aerospace, medical devices, automotive manufacturing, chemical engineering, energy, etc. In terms of improving polymers’ light transmittance, changing the polymer’s crystal structure into the amorphous structure by chemical modification was considered to be one of the most commonly methods presently. For example, Chen et al [ 13 ] synthesized a series of amorphous poly(ether ether ketone)s containing benzene pendant group in the molecular chain, the transparencies of copolmers’ films examined at 450 nm were 72.2–82.2%. Cyclohexyl was introduced into the molecular chain of poly(aryl ether ketone) to alter the crystal structure of PEEK by Lu et al [ 14 ] , the obtained polymer had good light transmittance of 81.3% at 450 nm. Li et al [ 15 ] synthesized a novel poly(aryl ether ketone) (PAEK) with low dielectric constant and high transparency by introducing fluorine atoms and phenolphthalein groups into the polymer back bone, and the transmittance at 450 nm were higher than 80%. In order to improve the optical property of the semi-aromatic polyamides, Zhang et al [ 16 ] selected bisphenol AP and isophorone diamine as the raw materials to obtain the light permeable semi-aromatic PAEAs with non-crystalline structure, the polymers showed good light transmittance of 83–85% at 450 nm. Luo et al [ 17 ] prepared the poly(arylene ether amide)s containing two aliphatic ring units in the main chain, the polymers had excellent solution film-forming property, and the optical transmittances of the films were 74–80% at 450 nm. Additionally, poly(aryl ether ketone)/semi-aromatic poly(ether ether amide) copolymers (PAEK/PEEA) with benzene pendant and different chain lengths in the chain was synthesized through nucleophilic substitution by a one-step method, the copolymers had good optical transmittance with the optical transmittance of 75.7–86.1% at 450 nm [ 9 ] . Lu et al [ 18 ] synthesized the co-polyarylates with low dielectric constant and high light transmittance using a bisphenol containing spiral ring, terephthaloyl acid chloride, isophthalic acid chloride and bisphenol A as the raw materials, the transparency of the supplied transparent films were 86.2–89.4% at 450 nm. The polyarylates containing tert-butyl cyclohexyl bulky side group were synthesized by Zhang et al [ 19 ] , the large space volume endowed polymers’ high transparency and low dielectric properties, and the transparencies were 81–88% at 450 nm. Poly(arylene ether nitrile) (PEN), as one of the most high-performance engineering plastics, has a relatively high degree of crystallization and extremely high melting point, which hinders its optical property. While the previous research mainly focused on the study of mechanical property, improvement of solubility, and functionality. In order to enhance the mechanical property of PEN, fillers (such as nano particles, fibers and so on) reinforcing had been thought to be an effect way to improve its mechanical property. Zhan et al [ 20 ] successfully prepared the cross-linkable nitrile functionalized graphene oxide/poly(arylene ether nitrile) nanocomposite films, the mechanical property of the films had been improved. Compared of the pure PEN copolymer, tensile strength reached up to 105.3 MPa, increased about 27%. You et al [ 21 ] also prepared the carbon nanotubes reinforcing poly(arylene ether nitrile) (PEN) composites through solution casting method, the prepared composite films exhibited outstanding mechanical property, the tensile strength was higher than that of the pure PEN, and the optimal value reached up to 126.7 MPa as the content of carbon nanotubes was 2 wt%. Tong et al [ 22 ] studied the effect of nano-silica on the mechanical property of PEN(SiO 2 /PEN-t-Ph) terminated with phthalonitrile. The results showed that SiO 2 /PEN-t-Ph nanocomposites with 12.0 wt% nano-SiO 2 loading exhibited the best mechanical performance with the tensile strength of 108.2 MPa and tensile modulus of 2.1 Gpa, increasing by 14% and 19%, respectively, comparing with the pure PEN-t-Ph film. Li et al [ 23 ] prepared poly(arylene ether nitrile)/glass fiber (PEN/GF) composites through melt blending. The tensile strength, flexural strength and izod impact strength of the composites got their highest values with GF content at 35 wt%, 30 wt% and 25 wt%, respectively. Additionally, PAENs had strongly polar nitrile groups in the side chain that can react with the other groups [ 24 ] . Introducing pendant methyl [ 25 ] , sulfonic acid group [ 26 – 27 ] or carboxyl groups [ 28 ] into the PEN’s molecular chain by chemical modification was considered to be the effective method to improve the solubility of crystalline PEN well. The imported groups could weak PEN’s crystallization property that make the synthesized polymers can dissolve in more organic solvents, such as, DMF, DMAC, CHCl 3 , DMSO and so on. Additionally, introducing sulfonic acid group [ 29 ] , naphthalene [ 30 ] in the PEN’s chain can endow them good proton conductivity, the obtained polymers can be made into proton conducting membrane materials for fuel cells. The fluorescent PEN (FPEN) can be synthesized via nucleophilic polymerization using phenolphthalin and 2, 6-dichlorobenzonitrile, the synthesized blue emitting FPEN was highly transparent in solution and film state under visible light [ 31 ] . Different average molecular weights of cyan fluorescent PEN end-capped with tetraphenylethene (TPE) were synthesized by Wang et al [ 32 ] . The obtained PENs showed typical aggregation-induced emission features under aggregation states in solvent-nonsolvent mixtures. Other functional PENs with special properties, such as good light transmittance, low dielectric property and good fuel cell performance were also reported. [11, 33–34 ] Presently, there are only few literatures about the improvement of PEN’s optical property. From the above, the light transmittance of the polymers can be effectively improved well by altering polymers’ crystallization property. In our previous work, two novel poly(arylene ether nitrile)s (CPDP-DCBN and CHDP-DCBN) containing pendant aliphatic ring were synthesized by nucleophilic substitution using NMP as the solvent, the polymer CPDP-DCBN exhibited good optical performance while CHDP-DCBN not because of its the local ordered structure. Additionally, we found that the introduction of alicyclic ring decreased the thermal property of PEN, which limited their application as high temperature resistant materials. Thus, in this work, fluorenyl group with large space volume was introduced to improve thermal and optical properties PEN containing aliphatic rings. Meanwhile, the solubility, thermal property and mechanical property, are also studied in detail. 2. Experimental 2.1. Materials 4, 4’-(9-fluorenylidene) diphenol (FDP, AR, Aladdin reagent), 4, 4’-cyclohexan-1, 1’-diyldiphenol (CHDP) and 4, 4’-cyclopentane-1, 1’-diyldiphenol (CPDP) were synthesized through our previous study 11 , 2, 6-dichlorobenzonitrile (DCBN, 99%) was obtained from Yangzhou Tianchen Fine Chemical Co Ltd. Potassium carbonate (K 2 CO 3 , AR) and toluene (AR) were purchased from Kelong Chemical Industry Company (Chengdu). N-methyl-2-pyrrolidone (NMP, 99%) was from Jinlong Chemical Industry Company (Jiangsu Nanjing). Other reagents were obtained commercially. 2.2 Polymer synthesis The typical synthesis route of copolymers was showed in Scheme 1 . Briefly, 5.086 g CHDP (0.02 mol), 7.008 g FDP (0.02 mol), 6.88 g DCBN (0.04 mol), 7.74 g K 2 CO 3 (0.056 mol), NMP 20 mL and methylbenzene 30 mL were added into a 250 mL three-necked round bottom equipped with a dehydrator, a thermometer, nitrogen entry under stirring condition. The temperature was then raised to 160 o C and kept for about 1 hour to remove the mixture of methylbenzene and water. Next, the temperature was heated to 200 o C and kept this temperature for several hours until the solution reached a high viscosity. After the reaction, the viscous solution was poured into distilled water to precipitate out polymer solid, and the crude solid was crashed into power and washed with hot distilled water for 3 times. The powdered polymer P-HFD (15.5 g, yield: 96.3%) was dried in a vaccum oven at 80°C for 24 h. The other copolymer P-PFD (16.3 g, yield: 99.8%) was synthesized by the similar procedure as that of P-HFD. 2.3. Characterizations The intrinsic viscosities of P-HFD and P-PFD were tested at 30 ± 0.1 o C using a Cannon-Ubbelodhe viscometer with 0.1250 g polymer dissolved in 25 mL NMP solution. The intrinsic viscosities of P-HFD and P-PFD were calculated by a one-point method (or Solomon–Ciuta equation) as follows: where η r = η/η 0 , η sp = η/η 0 − 1. FT-IR spectroscopy measurements (NEXUS670 FT-IR instrument) was used to examine the surface group of the copolymers. Nuclear magnetic resonance ( 1 H-NMR, BRUKER 400 NMR spectrometer) was used to study the copolymers’ structures, the solvent was deuterium chloroform (CDCl 3 ). Differential scanning calorimetry (DSC, Switzerland Mettler Toledo DSC-1 thermal analysis instrument) and thermogravimetric analysis (TGA, Switzerland Mettler Toledo thermal analysis instrument) were conducted to study the thermal properties of copolymers at N 2 atmosphere. During the DSC test, the temperature was heated from 40 o C to 400 o C by the heating rate of 50 o C/min, and then the temperature was maintained for about 1 min. Next, the temperature was cooled to 40 o C with a cooling rate of 10 o C/min, and maintained this temperature for 1 min. Finally, the temperature was rasied up to 300 o C with the heating rate of 10 o C/min. During the TGA test, the temperature was heated from to 40 o C to 800 o C, and the heating rate was 10 o C/min. The mechanical testing machine was used to study the stress–strain behaviors of all the copolymers, and the sizes of dumbbell spine of the films were about 50 mm* 8 mm* 4 mm, the films were prepared by solution method, the solution was NMP. The solubility of the polymers was tested with 0.1 g polymer immersed into 20 mL different solvents at room temperature with 12 hours. The optical properties of copolymers’ films were tested by UV-Visible spectroscopy (A580, AOE Instruments (Shanghai) Co., Ltd.), the films were by prepared by NMP solution. 3. Results and Discussion 3.1. Chain structures of P-HFD, P-PFD The FI-IR and 1 H-NMR spectra of P-HFD and P-PFD were used to study the structure of the synthesized copolymers, and the results were displayed in Fig. 1 , Fig. 2 and Fig. 3 , respectively. As shown in Fig. 1 , the peaks at 2919–2925 cm − 1 and 2850–2873 cm − 1 were the characteristic absorptions of -CH 2 - bond. The peaks at about 2228–2229 cm − 1 were attributed to the absorptions of –CN group. The characteristic absorption of benzene ring could be observed at 1450–1458 cm − 1 , 1502–1508 cm − 1 and 1602–1631 cm − 1 , and the characteristic absorptions of C-O-C bond were near 1016–1024 cm − 1 and 1207–1247 cm − 1 . Figure 2 and Fig. 3 were the 1 H-NMR spectra of P-HFD and P-PFD in CDCl 3 , respectively. From Fig. 2 , the signals at 7.68–7.74 ppm and 7.28–7.39 ppm were attributed to the aromatic protons that from fluorenyl group. The other signals at 7.20–7.26 ppm, 7.12–7.18 ppm, 6.92–6.98 ppm, 6.86–6.92 ppm and 6.36–6.42 ppm were assigned to aromatic protons from benzene ring and fluorenyl group. The peaks at 2.15–2.26 ppm, 1.41–1.56 ppm were from cyclohexyl unit. Similarly, the signals at 7.76–7.80 ppm, 7.36–7.43 ppm, 7.27–7.32 ppm, 7.18–7.24 ppm, 6.98–7.03 ppm, 6.93–6.98 ppm and 6.42–6.49 ppm, at 2.26–2.33 ppm and 1.71–1.79 ppm were assigned to the aromatic protons and cyclopentane units, respectively. And the ratios of corresponding integral curves were close to the theoretical values. Combining the results of FT-IR and 1 H–NMR, it could be concluded two novel copolymers P-HFD and P-PFD were successfully synthesized in this work. 3.2. The aggregative structures of P-HFD, P-PFD X-ray diffraction (XRD) was used to study the aggregative structures of these two copolymers P-HFD and P-PFD. Figure 4 was the XRD spectra of the copolymers. From the figure, it could be found that there were no obvious crystalline peaks in the XRD spectra of P-HFD and P-PFD, indicating the synthesized polymers were amorphous. Compared with CPDP-DCBN and CHDP-DCBN, prepared in the previous work [ 11 ] , the spectra become more wider, implying the crystal structure of P-HFD and P-PFD had changed. Especially, the crystal structure of P-HFD changed from partial crystalline to amorphous. 3.3. The thermal property of P-HFD, P-PFD The thermal properties of the synthesized polymers P-HFD, P-PFD were examined by DSC and TGA, and the results were shown in Fig. 5 and Fig. 6 . As shown in Fig. 5 , it could be found the synthesized two copolymers had no obvious melting points and crystallization peaks, indicating the copolymers were amorphous. We could also find that the glass transition temperatures (T g ) of P-HFD and P-PFD were 202.2 o C and 214.9 o C, respectively. The values were much higher than that of the first commercialized product of PAENs (T g =148°C), the polymers CPDP-DCBN (T g =185.4°C) and CHDP-DCBN (T g =196.4°C) [ 11 ] . The reason was that the rigidity of the polymer chain was increased by the introduction of fluorenyl group, its large volume also caused the steric resistance of rotation within the molecular chain to increase, making the molecular chain more difficult to move, thereby increasing the glass transition temperature of the polymer. Additionally, the copolymer P-HFD had higher glass transition temperature than that of the copolymer P-PFD, which was also caused by the lager steric hindrance of cyclohexyl. As shown in Fig. 6 , the two copolymers presented a single degradation stage. The initial degradation temperatures (T 5% ) of P-HFD and P-PFD were 421.3 o C and 433.5 o C, respectively. The char yields of P-HFD and P-PFD were 44.2% and 48.9%, respectively. Here, the heat resistance index was also used to evaluate the thermal property of the polymers. And it could be calculated by the Eq. 0.49*[T 5% +0.6*(T 30% -T 5% )], where T 5% and T 30% are the corresponding decomposing temperature at 5% and 30% weight loss, respectively [ 35 ] . And the heat resistance indexes of P-HFD and P-PFD were 221.0 o C and 229.1 o C, respectively. All of these results showed that the synthesized copolymers had good thermal property. 3.4. The inherent viscosities (η int ) and mechanical property of P-HFD and P-PFD Inherent viscosities of the obtained copolymers P-HFD, P-PFD were examined by one-point method with a Cannon-Ubbelodhe viscometer, and their inherent viscosities were 0.455 dL g − 1 and 0.576 dL g − 1 , respectively. The results indicated that the synthesized polymers might have moderate molecular weight. The tensile strength of copolymers P-HFD and P-PFD were tested by the mechanical testing machine. The average tensile strengths of P-HFD and P-PFD were 27.3 MPa and 38.6 MPa, respectively, implying they had good mechanical property. 3.5. Corrosion resistance The solubility of the synthesized copolymers P-HFD and P-PFD were showed in Table 1 . The two copolymers were found to be soluble completely in NMP, DMF and CH 2 Cl 2 at room temperature, and were partially soluble in DMSO. The polymer P-PFD could be soluble completely in CHCl 3 and partially soluble in toluene, acetone. While P-HFD was insoluble in CHCl 3 , toluene, acetone. The copolymer P-PFD exhibited slightly better dissolving property than that of P-HFD due to its more disordered structure. Comparing with the homopolymers CPDP-DCBN and CHDP-DCBN, the copolymers P-HFD and P-PFD exhibited better dissolving property, indicating the introduction of fluorenyl unit might disrupt the partial regularity of the polymers. Additionally, both the copolymers were insoluble in many solutions, such as concentrated HCl, NaOH solution, ethanol, H 2 O and so on. The results showed that the obtained copolymers showed moderate corrosion resistance. Table 1 Solubility behavior of copolymers P-HFD and P-PFD Solvent/Sample P-HFD P-PFD HCl (6 mol L − 1 ) - - Toluene - +- NMP + + DMF + + NaOH (1 mol L − 1 ) - - Acetone - +- CH 2 Cl 2 + + Ethanol - - DMSO +- +- CHCl 3 - + H 2 O - - 3.6. Optical performance analysis The optical properties of copolymers’ films were tested by UV-Visible spectroscopy. Figure 7 was the UV-Visible spectroscopy of the copolymers P-HFD and P-PFD, and the thickness of them were 46 µm and 44 µm, respectively. From the figure, the cutoff wavelengths (λ cut off ) of the films were about 323 nm. The transmittances of P-HFD at 400, 450 nm were 70.4% and 76.3%, respectively. P-PFD’s were 61.6% and 68.3%, respectively. Comparing with the polymer CPDP-DCBN, P-PFD exhibited slightly weaker transmittance might be caused by its thicker thickness. The copolymer P-HFD showed good optical property but CHDP-DCBN not, the reason might be that introducing fluorenyl unit into the chain of CHDP-DCBN destroyed the polymer’s local crystal structure. The result showed that the films of P-HFD and P-PFD had good optical property, and they can be potentially applied as the novel materials for the optical film. 4. Conclusion The novel poly(arylene ether nitrile) copolymers (P-HFD and P-PFD) containing pendant aliphatic ring and fluorene groups were successfully synthesized by 4,4’-cyclohexane-1, 1’-diyldiphenol (CHDP) or 4, 4’-cyclopentane-1, 1’-diyldiphenol (CPDP), 4, 4’-(9-fluorenylidene) diphenol and 2,6-dichlorobenzonitrile (DCBN) in the work. The synthesized copolymers were amorphous and found to have good mechanical property. The thermal property and dissolving property were improved well because of the introduction of fluorene group that broken the polymer’s local crystal structure. Additionally, the synthesized polymers showed good transmittance with 61.6%-70.4% at 400 nm and 68.3%-76.3% at 450 nm, indicating that they could be potentially applied as the novel heat-resistant optical materials. Declarations Acknowledgements This work was supported by Natural Science Foundation of Sichuan Province (2024NSFSC1847). Author Contribution Shajie Luo : Conceptualization, Investigation, Writing-original draft. Yuan Wang : Data Curation, Investigation, Writing-original draft. Shuai Zhang : Resources, Date validation, Project Administration. Zhou Jun : Literature Survey, Database Construction, Comparative Analysis. Jiale Wang : Literature Survey, Performance test. Xiaohan Wang : Literature Survey, Performance test. Lishi Jiang : Conceptualization, Resources, Supervision, Methodology, Writing-original draft, Writing- review & editing. Data availability All data included in this study are available upon request by contact with the corresponding author. Competing interest declaration The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. References Duan Y, Yang H, Liu K, Xu T, Chen J, Xie H, Du H, Dai L, Si C (2023) Cellulose nanofibril aerogels reinforcing polymethyl methacrylate with high optical transparency. Adv Compos Hybrid Mater 6:123 Ouradi A, Cherifi N, Afir Y, Bouta C, Bencherik R, Benaboura A (2025) Filler effect on properties of polymethyl methacrylate-based membranes for hemodialysis application. 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Polymer 259:125361 Yan DW, Li XD, Li PC, Tang WL, Ren HH, Yan YG (2021) Conferring fluorescence tracking function to polyphenylene sulfide by embedding the pyrene into the backbone at the molecular level: Design and synthesis. Polymer 237. Scheme 1 Scheme 1 is available in the Supplementary Files section. Supplementary Files SC1.jpg Scheme. 1. Synthesis route of the copolymers P-HFD and P-PFD Cite Share Download PDF Status: Published Journal Publication published 11 Dec, 2025 Read the published version in Journal of Polymer Research → Version 1 posted Reviewers agreed at journal 03 Sep, 2025 Reviewers invited by journal 03 Sep, 2025 Editor invited by journal 16 Aug, 2025 Editor assigned by journal 22 Jul, 2025 First submitted to journal 21 Jul, 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. 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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-7156844","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":509524335,"identity":"63bc0787-5189-4244-a094-08a55635061e","order_by":0,"name":"Shajie Luo","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Shajie","middleName":"","lastName":"Luo","suffix":""},{"id":509524336,"identity":"1b233933-3986-490b-853b-fc733e190b46","order_by":1,"name":"Yuan Wang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Yuan","middleName":"","lastName":"Wang","suffix":""},{"id":509524337,"identity":"ec15ca35-84ff-499d-89c2-5c5a7ad67634","order_by":2,"name":"Shuai Zhang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Shuai","middleName":"","lastName":"Zhang","suffix":""},{"id":509524338,"identity":"6fdc5f48-e5d6-4ffc-9525-176443bff4d1","order_by":3,"name":"Zhou Jun","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Zhou","middleName":"","lastName":"Jun","suffix":""},{"id":509524339,"identity":"c3920236-7d3c-4708-9419-dbf3e6fb2435","order_by":4,"name":"Jiale Wang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Jiale","middleName":"","lastName":"Wang","suffix":""},{"id":509524340,"identity":"7c166de2-c680-4828-aa2e-07e98f227395","order_by":5,"name":"Xiaohan Wang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Xiaohan","middleName":"","lastName":"Wang","suffix":""},{"id":509524341,"identity":"3c8aa848-3d68-49c3-8aa3-55b49f65409f","order_by":6,"name":"Lishi Jiang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA0klEQVRIiWNgGAWjYBACxnbGBmYGAxsGhgNQgQaCWprBWtKAWpiJ1MLADEaHSdDC3Mzc/Lmg4Lw83438g59uMNjIbjjA/OwBAYe1Sc8wuG0480Yys3QOQ5rxhgNs5gaEtDDzGNxOMLiRzMacw3A4ccMBHjYJAlqaP/MYnINp+U+UlgZpHoMDMC0HiNLSBtSSbDjzzGNj6RyDZOOZh9nM8GoxbG9//Jnnj5083/HEh59zKuxk+443P8OvpQGFCwoqZnzqgUCegPwoGAWjYBSMAgYGAAJHRTlFzofnAAAAAElFTkSuQmCC","orcid":"","institution":"Chengdu University of Traditional Chinese Medicine","correspondingAuthor":true,"prefix":"","firstName":"Lishi","middleName":"","lastName":"Jiang","suffix":""}],"badges":[],"createdAt":"2025-07-18 10:43:02","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7156844/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7156844/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10965-025-04700-w","type":"published","date":"2025-12-11T15:57:09+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":90935821,"identity":"57416e61-f7c5-4162-a1d7-b0242a8abab8","added_by":"auto","created_at":"2025-09-09 17:03:32","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":65703,"visible":true,"origin":"","legend":"\u003cp\u003eFT-IR spectra of copolymers P-HFD and P-PFD\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7156844/v1/8e7262f413a91cbe60ab1ae4.jpg"},{"id":90935822,"identity":"7a76fed4-f2ba-4f7f-9fb9-606e7dd4ea55","added_by":"auto","created_at":"2025-09-09 17:03:32","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":186131,"visible":true,"origin":"","legend":"\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eH-NMR spectra of polymer P-HFD in CDCl\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7156844/v1/4e807bbd2022c7f26ab9be09.png"},{"id":90935832,"identity":"d7e1d3fd-cc86-4874-b9db-5556b6954be7","added_by":"auto","created_at":"2025-09-09 17:03:46","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":207707,"visible":true,"origin":"","legend":"\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eH-NMR spectra of polymer P-PFD in CDCl\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7156844/v1/55703abaa1a7729bc27b390a.png"},{"id":90935828,"identity":"d8325891-9fed-4920-9933-af45229e385c","added_by":"auto","created_at":"2025-09-09 17:03:33","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":61020,"visible":true,"origin":"","legend":"\u003cp\u003eThe XRD spectra of P-HFD and P-PFD\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7156844/v1/fab811f0b176e182bcd87f14.jpg"},{"id":90935800,"identity":"0eb5dc1c-5b66-4958-8e5b-523700bca0b0","added_by":"auto","created_at":"2025-09-09 17:03:28","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":129399,"visible":true,"origin":"","legend":"\u003cp\u003e(a) The second DSC heating curves of polymers P-HFD and P-PFD, (b) the cooling DSC curves of P-HFD and P-PFD\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7156844/v1/177f0caab2e0b6d8056ef5af.png"},{"id":90935830,"identity":"af0d7b94-3d61-417d-9518-989d63081965","added_by":"auto","created_at":"2025-09-09 17:03:36","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":71829,"visible":true,"origin":"","legend":"\u003cp\u003eTGA curves of polymers P-HFD and P-PFD\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7156844/v1/976818dc4f9a9b580d034ffd.jpg"},{"id":90935823,"identity":"05d04bce-4f9d-4cd4-a56c-1da839f6deac","added_by":"auto","created_at":"2025-09-09 17:03:32","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":68162,"visible":true,"origin":"","legend":"\u003cp\u003eThe optical property of the copolymers P-HFD and P-PFD\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7156844/v1/aa3cb756658b08fe775c7a1c.jpg"},{"id":98243736,"identity":"1ea8c7f6-2e4b-48eb-b963-cbb14e71feb9","added_by":"auto","created_at":"2025-12-15 16:10:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1428258,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7156844/v1/51a19c56-67b4-4c5e-8b9e-f63543323e6c.pdf"},{"id":90935781,"identity":"79ecaf2a-435d-4a11-a5ec-13e054a713af","added_by":"auto","created_at":"2025-09-09 17:03:28","extension":"jpg","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":30924,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme. 1.\u003c/strong\u003e Synthesis route of the copolymers P-HFD and P-PFD\u003c/p\u003e","description":"","filename":"SC1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7156844/v1/743f48c454e78b6e9e070d4b.jpg"}],"financialInterests":"","formattedTitle":"Novel transparent poly(arylene ether nitrile) copolymers with pendant aliphatic ring: synthesis and characterization","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eTransparent polymers refer to a class of polymers with good transparency and physical property. The transparent polymers are mainly divided to aliphatic transparent polymers and aromatic polymers. Comparing with aliphatic transparent polymers (poly(methyl methacrylate) (PMMA)\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e, transparent polyamide 1012\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e, polyethylene (PE\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e), polyvinyl alcohol (PVA)\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e etc), aromatic transparent polymers (transparent polyethylene terephthalate (PET)\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e, polyimide\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e, semi-aromatic polyamide \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e, etc) have better thermal resistance, mechanical property, radiation resistance, flame-retardant property, etc. This makes them be widely applied in mechanical load-bearing components, high-temperature resistance, radiation resistance fields and so on.\u003c/p\u003e\u003cp\u003eAromatic polymers, such as poly(ether ether ketone) (PEEK) \u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e, poly(ether ether mide) (PEEA) \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e, poly(arylene ether nitrile) (PEN) \u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e, thermotropic liquid crystal polymer (TLCP) \u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e, etc, have good chain regularity and crystallinity, which endow them with high melting points, thermodynamic property, corrosion resistance, etc. While the high crystallinity reduces their light transmittances, thereby affecting their special applications in the fields of information electronics, aerospace, medical devices, automotive manufacturing, chemical engineering, energy, etc. In terms of improving polymers\u0026rsquo; light transmittance, changing the polymer\u0026rsquo;s crystal structure into the amorphous structure by chemical modification was considered to be one of the most commonly methods presently. For example, Chen et al\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e synthesized a series of amorphous poly(ether ether ketone)s containing benzene pendant group in the molecular chain, the transparencies of copolmers\u0026rsquo; films examined at 450 nm were 72.2\u0026ndash;82.2%. Cyclohexyl was introduced into the molecular chain of poly(aryl ether ketone) to alter the crystal structure of PEEK by Lu et al \u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e, the obtained polymer had good light transmittance of 81.3% at 450 nm. Li et al \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e synthesized a novel poly(aryl ether ketone) (PAEK) with low dielectric constant and high transparency by introducing fluorine atoms and phenolphthalein groups into the polymer back bone, and the transmittance at 450 nm were higher than 80%. In order to improve the optical property of the semi-aromatic polyamides, Zhang et al \u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e selected bisphenol AP and isophorone diamine as the raw materials to obtain the light permeable semi-aromatic PAEAs with non-crystalline structure, the polymers showed good light transmittance of 83\u0026ndash;85% at 450 nm. Luo et al\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e prepared the poly(arylene ether amide)s containing two aliphatic ring units in the main chain, the polymers had excellent solution film-forming property, and the optical transmittances of the films were 74\u0026ndash;80% at 450 nm. Additionally, poly(aryl ether ketone)/semi-aromatic poly(ether ether amide) copolymers (PAEK/PEEA) with benzene pendant and different chain lengths in the chain was synthesized through nucleophilic substitution by a one-step method, the copolymers had good optical transmittance with the optical transmittance of 75.7\u0026ndash;86.1% at 450 nm\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. Lu et al \u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e synthesized the co-polyarylates with low dielectric constant and high light transmittance using a bisphenol containing spiral ring, terephthaloyl acid chloride, isophthalic acid chloride and bisphenol A as the raw materials, the transparency of the supplied transparent films were 86.2\u0026ndash;89.4% at 450 nm. The polyarylates containing tert-butyl cyclohexyl bulky side group were synthesized by Zhang et al\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e, the large space volume endowed polymers\u0026rsquo; high transparency and low dielectric properties, and the transparencies were 81\u0026ndash;88% at 450 nm.\u003c/p\u003e\u003cp\u003ePoly(arylene ether nitrile) (PEN), as one of the most high-performance engineering plastics, has a relatively high degree of crystallization and extremely high melting point, which hinders its optical property. While the previous research mainly focused on the study of mechanical property, improvement of solubility, and functionality. In order to enhance the mechanical property of PEN, fillers (such as nano particles, fibers and so on) reinforcing had been thought to be an effect way to improve its mechanical property. Zhan et al \u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e successfully prepared the cross-linkable nitrile functionalized graphene oxide/poly(arylene ether nitrile) nanocomposite films, the mechanical property of the films had been improved. Compared of the pure PEN copolymer, tensile strength reached up to 105.3 MPa, increased about 27%. You et al \u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e also prepared the carbon nanotubes reinforcing poly(arylene ether nitrile) (PEN) composites through solution casting method, the prepared composite films exhibited outstanding mechanical property, the tensile strength was higher than that of the pure PEN, and the optimal value reached up to 126.7 MPa as the content of carbon nanotubes was 2 wt%. Tong et al \u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e studied the effect of nano-silica on the mechanical property of PEN(SiO\u003csub\u003e2\u003c/sub\u003e/PEN-t-Ph) terminated with phthalonitrile. The results showed that SiO\u003csub\u003e2\u003c/sub\u003e/PEN-t-Ph nanocomposites with 12.0 wt% nano-SiO\u003csub\u003e2\u003c/sub\u003e loading exhibited the best mechanical performance with the tensile strength of 108.2 MPa and tensile modulus of 2.1 Gpa, increasing by 14% and 19%, respectively, comparing with the pure PEN-t-Ph film. Li et al \u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e prepared poly(arylene ether nitrile)/glass fiber (PEN/GF) composites through melt blending. The tensile strength, flexural strength and izod impact strength of the composites got their highest values with GF content at 35 wt%, 30 wt% and 25 wt%, respectively. Additionally, PAENs had strongly polar nitrile groups in the side chain that can react with the other groups\u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e. Introducing pendant methyl\u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e, sulfonic acid group \u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e or carboxyl groups \u003csup\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e into the PEN\u0026rsquo;s molecular chain by chemical modification was considered to be the effective method to improve the solubility of crystalline PEN well. The imported groups could weak PEN\u0026rsquo;s crystallization property that make the synthesized polymers can dissolve in more organic solvents, such as, DMF, DMAC, CHCl\u003csub\u003e3\u003c/sub\u003e, DMSO and so on. Additionally, introducing sulfonic acid group \u003csup\u003e[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e, naphthalene \u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e in the PEN\u0026rsquo;s chain can endow them good proton conductivity, the obtained polymers can be made into proton conducting membrane materials for fuel cells. The fluorescent PEN (FPEN) can be synthesized via nucleophilic polymerization using phenolphthalin and 2, 6-dichlorobenzonitrile, the synthesized blue emitting FPEN was highly transparent in solution and film state under visible light \u003csup\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/sup\u003e. Different average molecular weights of cyan fluorescent PEN end-capped with tetraphenylethene (TPE) were synthesized by Wang et al\u003csup\u003e[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e. The obtained PENs showed typical aggregation-induced emission features under aggregation states in solvent-nonsolvent mixtures. Other functional PENs with special properties, such as good light transmittance, low dielectric property and good fuel cell performance were also reported. \u003csup\u003e[11, 33\u0026ndash;34 ]\u003c/sup\u003e\u003c/p\u003e\u003cp\u003ePresently, there are only few literatures about the improvement of PEN\u0026rsquo;s optical property. From the above, the light transmittance of the polymers can be effectively improved well by altering polymers\u0026rsquo; crystallization property. In our previous work, two novel poly(arylene ether nitrile)s (CPDP-DCBN and CHDP-DCBN) containing pendant aliphatic ring were synthesized by nucleophilic substitution using NMP as the solvent, the polymer CPDP-DCBN exhibited good optical performance while CHDP-DCBN not because of its the local ordered structure. Additionally, we found that the introduction of alicyclic ring decreased the thermal property of PEN, which limited their application as high temperature resistant materials. Thus, in this work, fluorenyl group with large space volume was introduced to improve thermal and optical properties PEN containing aliphatic rings. Meanwhile, the solubility, thermal property and mechanical property, are also studied in detail.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Materials\u003c/h2\u003e\u003cp\u003e4, 4\u0026rsquo;-(9-fluorenylidene) diphenol (FDP, AR, Aladdin reagent), 4, 4\u0026rsquo;-cyclohexan-1, 1\u0026rsquo;-diyldiphenol (CHDP) and 4, 4\u0026rsquo;-cyclopentane-1, 1\u0026rsquo;-diyldiphenol (CPDP) were synthesized through our previous study \u003csup\u003e11\u003c/sup\u003e, 2, 6-dichlorobenzonitrile (DCBN, 99%) was obtained from Yangzhou Tianchen Fine Chemical Co Ltd. Potassium carbonate (K\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e, AR) and toluene (AR) were purchased from Kelong Chemical Industry Company (Chengdu). N-methyl-2-pyrrolidone (NMP, 99%) was from Jinlong Chemical Industry Company (Jiangsu Nanjing). Other reagents were obtained commercially.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Polymer synthesis\u003c/h2\u003e\u003cp\u003eThe typical synthesis route of copolymers was showed in Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Briefly, 5.086 g CHDP (0.02 mol), 7.008 g FDP (0.02 mol), 6.88 g DCBN (0.04 mol), 7.74 g K\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e (0.056 mol), NMP 20 mL and methylbenzene 30 mL were added into a 250 mL three-necked round bottom equipped with a dehydrator, a thermometer, nitrogen entry under stirring condition. The temperature was then raised to 160 \u003csup\u003eo\u003c/sup\u003eC and kept for about 1 hour to remove the mixture of methylbenzene and water. Next, the temperature was heated to 200 \u003csup\u003eo\u003c/sup\u003eC and kept this temperature for several hours until the solution reached a high viscosity. After the reaction, the viscous solution was poured into distilled water to precipitate out polymer solid, and the crude solid was crashed into power and washed with hot distilled water for 3 times. The powdered polymer P-HFD (15.5 g, yield: 96.3%) was dried in a vaccum oven at 80\u0026deg;C for 24 h. The other copolymer P-PFD (16.3 g, yield: 99.8%) was synthesized by the similar procedure as that of P-HFD.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3. Characterizations\u003c/h2\u003e\u003cp\u003eThe intrinsic viscosities of P-HFD and P-PFD were tested at 30\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1 \u003csup\u003eo\u003c/sup\u003eC using a Cannon-Ubbelodhe viscometer with 0.1250 g polymer dissolved in 25 mL NMP solution. The intrinsic viscosities of P-HFD and P-PFD were calculated by a one-point method (or Solomon\u0026ndash;Ciuta equation) as follows:\u003c/p\u003e\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/p\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003c/span\u003e\u003c/p\u003e\u003cp\u003ewhere \u003cem\u003eη\u003c/em\u003e\u003csub\u003er\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003eη/η\u003c/em\u003e\u003csub\u003e0\u003c/sub\u003e, \u003cem\u003eη\u003c/em\u003e\u003csub\u003esp\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;\u003cem\u003eη/η\u003c/em\u003e\u003csub\u003e0\u003c/sub\u003e\u0026thinsp;\u0026minus;\u0026thinsp;1.\u003c/p\u003e\u003cp\u003eFT-IR spectroscopy measurements (NEXUS670 FT-IR instrument) was used to examine the surface group of the copolymers. Nuclear magnetic resonance (\u003csup\u003e1\u003c/sup\u003eH-NMR, BRUKER 400 NMR spectrometer) was used to study the copolymers\u0026rsquo; structures, the solvent was deuterium chloroform (CDCl\u003csub\u003e3\u003c/sub\u003e). Differential scanning calorimetry (DSC, Switzerland Mettler Toledo DSC-1 thermal analysis instrument) and thermogravimetric analysis (TGA, Switzerland Mettler Toledo thermal analysis instrument) were conducted to study the thermal properties of copolymers at N\u003csub\u003e2\u003c/sub\u003e atmosphere. During the DSC test, the temperature was heated from 40 \u003csup\u003eo\u003c/sup\u003eC to 400 \u003csup\u003eo\u003c/sup\u003eC by the heating rate of 50 \u003csup\u003eo\u003c/sup\u003eC/min, and then the temperature was maintained for about 1 min. Next, the temperature was cooled to 40 \u003csup\u003eo\u003c/sup\u003eC with a cooling rate of 10 \u003csup\u003eo\u003c/sup\u003eC/min, and maintained this temperature for 1 min. Finally, the temperature was rasied up to 300 \u003csup\u003eo\u003c/sup\u003eC with the heating rate of 10 \u003csup\u003eo\u003c/sup\u003eC/min. During the TGA test, the temperature was heated from to 40 \u003csup\u003eo\u003c/sup\u003eC to 800 \u003csup\u003eo\u003c/sup\u003eC, and the heating rate was 10 \u003csup\u003eo\u003c/sup\u003eC/min. The mechanical testing machine was used to study the stress\u0026ndash;strain behaviors of all the copolymers, and the sizes of dumbbell spine of the films were about 50 mm* 8 mm* 4 mm, the films were prepared by solution method, the solution was NMP. The solubility of the polymers was tested with 0.1 g polymer immersed into 20 mL different solvents at room temperature with 12 hours. The optical properties of copolymers\u0026rsquo; films were tested by UV-Visible spectroscopy (A580, AOE Instruments (Shanghai) Co., Ltd.), the films were by prepared by NMP solution.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e3.1. Chain structures of P-HFD, P-PFD\u003c/h2\u003e\u003cp\u003eThe FI-IR and \u003csup\u003e1\u003c/sup\u003eH-NMR spectra of P-HFD and P-PFD were used to study the structure of the synthesized copolymers, and the results were displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, respectively. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the peaks at 2919\u0026ndash;2925 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 2850\u0026ndash;2873 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were the characteristic absorptions of -CH\u003csub\u003e2\u003c/sub\u003e- bond. The peaks at about 2228\u0026ndash;2229 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were attributed to the absorptions of \u0026ndash;CN group. The characteristic absorption of benzene ring could be observed at 1450\u0026ndash;1458 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 1502\u0026ndash;1508 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1602\u0026ndash;1631 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and the characteristic absorptions of C-O-C bond were near 1016\u0026ndash;1024 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1207\u0026ndash;1247 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e were the \u003csup\u003e1\u003c/sup\u003eH-NMR spectra of P-HFD and P-PFD in CDCl\u003csub\u003e3\u003c/sub\u003e, respectively. From Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the signals at 7.68\u0026ndash;7.74 ppm and 7.28\u0026ndash;7.39 ppm were attributed to the aromatic protons that from fluorenyl group. The other signals at 7.20\u0026ndash;7.26 ppm, 7.12\u0026ndash;7.18 ppm, 6.92\u0026ndash;6.98 ppm, 6.86\u0026ndash;6.92 ppm and 6.36\u0026ndash;6.42 ppm were assigned to aromatic protons from benzene ring and fluorenyl group. The peaks at 2.15\u0026ndash;2.26 ppm, 1.41\u0026ndash;1.56 ppm were from cyclohexyl unit. Similarly, the signals at 7.76\u0026ndash;7.80 ppm, 7.36\u0026ndash;7.43 ppm, 7.27\u0026ndash;7.32 ppm, 7.18\u0026ndash;7.24 ppm, 6.98\u0026ndash;7.03 ppm, 6.93\u0026ndash;6.98 ppm and 6.42\u0026ndash;6.49 ppm, at 2.26\u0026ndash;2.33 ppm and 1.71\u0026ndash;1.79 ppm were assigned to the aromatic protons and cyclopentane units, respectively. And the ratios of corresponding integral curves were close to the theoretical values. Combining the results of FT-IR and \u003csup\u003e1\u003c/sup\u003eH\u0026ndash;NMR, it could be concluded two novel copolymers P-HFD and P-PFD were successfully synthesized in this work.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e3.2. The aggregative structures of P-HFD, P-PFD\u003c/h2\u003e\u003cp\u003eX-ray diffraction (XRD) was used to study the aggregative structures of these two copolymers P-HFD and P-PFD. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e was the XRD spectra of the copolymers. From the figure, it could be found that there were no obvious crystalline peaks in the XRD spectra of P-HFD and P-PFD, indicating the synthesized polymers were amorphous. Compared with CPDP-DCBN and CHDP-DCBN, prepared in the previous work\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e, the spectra become more wider, implying the crystal structure of P-HFD and P-PFD had changed. Especially, the crystal structure of P-HFD changed from partial crystalline to amorphous.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.3. The thermal property of P-HFD, P-PFD\u003c/h2\u003e\u003cp\u003eThe thermal properties of the synthesized polymers P-HFD, P-PFD were examined by DSC and TGA, and the results were shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, it could be found the synthesized two copolymers had no obvious melting points and crystallization peaks, indicating the copolymers were amorphous. We could also find that the glass transition temperatures (T\u003csub\u003eg\u003c/sub\u003e) of P-HFD and P-PFD were 202.2 \u003csup\u003eo\u003c/sup\u003eC and 214.9 \u003csup\u003eo\u003c/sup\u003eC, respectively. The values were much higher than that of the first commercialized product of PAENs (T\u003csub\u003eg\u003c/sub\u003e=148\u0026deg;C), the polymers CPDP-DCBN (T\u003csub\u003eg\u003c/sub\u003e=185.4\u0026deg;C) and CHDP-DCBN (T\u003csub\u003eg\u003c/sub\u003e=196.4\u0026deg;C) \u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. The reason was that the rigidity of the polymer chain was increased by the introduction of fluorenyl group, its large volume also caused the steric resistance of rotation within the molecular chain to increase, making the molecular chain more difficult to move, thereby increasing the glass transition temperature of the polymer. Additionally, the copolymer P-HFD had higher glass transition temperature than that of the copolymer P-PFD, which was also caused by the lager steric hindrance of cyclohexyl. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, the two copolymers presented a single degradation stage. The initial degradation temperatures (T\u003csub\u003e5%\u003c/sub\u003e) of P-HFD and P-PFD were 421.3 \u003csup\u003eo\u003c/sup\u003eC and 433.5 \u003csup\u003eo\u003c/sup\u003eC, respectively. The char yields of P-HFD and P-PFD were 44.2% and 48.9%, respectively. Here, the heat resistance index was also used to evaluate the thermal property of the polymers. And it could be calculated by the Eq.\u0026nbsp;0.49*[T\u003csub\u003e5%\u003c/sub\u003e+0.6*(T\u003csub\u003e30%\u003c/sub\u003e-T\u003csub\u003e5%\u003c/sub\u003e)], where T\u003csub\u003e5%\u003c/sub\u003e and T\u003csub\u003e30%\u003c/sub\u003e are the corresponding decomposing temperature at 5% and 30% weight loss, respectively\u003csup\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e. And the heat resistance indexes of P-HFD and P-PFD were 221.0 \u003csup\u003eo\u003c/sup\u003eC and 229.1 \u003csup\u003eo\u003c/sup\u003eC, respectively. All of these results showed that the synthesized copolymers had good thermal property.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.4. The inherent viscosities (η\u003csub\u003eint\u003c/sub\u003e) and mechanical property of P-HFD and P-PFD\u003c/h2\u003e\u003cp\u003eInherent viscosities of the obtained copolymers P-HFD, P-PFD were examined by one-point method with a Cannon-Ubbelodhe viscometer, and their inherent viscosities were 0.455 dL g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 0.576 dL g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. The results indicated that the synthesized polymers might have moderate molecular weight. The tensile strength of copolymers P-HFD and P-PFD were tested by the mechanical testing machine. The average tensile strengths of P-HFD and P-PFD were 27.3 MPa and 38.6 MPa, respectively, implying they had good mechanical property.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.5. Corrosion resistance\u003c/h2\u003e\u003cp\u003eThe solubility of the synthesized copolymers P-HFD and P-PFD were showed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The two copolymers were found to be soluble completely in NMP, DMF and CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e at room temperature, and were partially soluble in DMSO. The polymer P-PFD could be soluble completely in CHCl\u003csub\u003e3\u003c/sub\u003e and partially soluble in toluene, acetone. While P-HFD was insoluble in CHCl\u003csub\u003e3\u003c/sub\u003e, toluene, acetone. The copolymer P-PFD exhibited slightly better dissolving property than that of P-HFD due to its more disordered structure. Comparing with the homopolymers CPDP-DCBN and CHDP-DCBN, the copolymers P-HFD and P-PFD exhibited better dissolving property, indicating the introduction of fluorenyl unit might disrupt the partial regularity of the polymers. Additionally, both the copolymers were insoluble in many solutions, such as concentrated HCl, NaOH solution, ethanol, H\u003csub\u003e2\u003c/sub\u003eO and so on. The results showed that the obtained copolymers showed moderate corrosion resistance.\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\u003eSolubility behavior of copolymers P-HFD and P-PFD\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"3\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSolvent/Sample\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eP-HFD\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eP-PFD\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHCl (6 mol L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eToluene\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e+-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNMP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDMF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNaOH (1 mol L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAcetone\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e+-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEthanol\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDMSO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e+-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e+-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCHCl\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e+\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.6. Optical performance analysis\u003c/h2\u003e\u003cp\u003eThe optical properties of copolymers\u0026rsquo; films were tested by UV-Visible spectroscopy. Figure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e was the UV-Visible spectroscopy of the copolymers P-HFD and P-PFD, and the thickness of them were 46 \u0026micro;m and 44 \u0026micro;m, respectively. From the figure, the cutoff wavelengths (λ\u003csub\u003ecut off\u003c/sub\u003e) of the films were about 323 nm. The transmittances of P-HFD at 400, 450 nm were 70.4% and 76.3%, respectively. P-PFD\u0026rsquo;s were 61.6% and 68.3%, respectively. Comparing with the polymer CPDP-DCBN, P-PFD exhibited slightly weaker transmittance might be caused by its thicker thickness. The copolymer P-HFD showed good optical property but CHDP-DCBN not, the reason might be that introducing fluorenyl unit into the chain of CHDP-DCBN destroyed the polymer\u0026rsquo;s local crystal structure. The result showed that the films of P-HFD and P-PFD had good optical property, and they can be potentially applied as the novel materials for the optical film.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThe novel poly(arylene ether nitrile) copolymers (P-HFD and P-PFD) containing pendant aliphatic ring and fluorene groups were successfully synthesized by 4,4\u0026rsquo;-cyclohexane-1, 1\u0026rsquo;-diyldiphenol (CHDP) or 4, 4\u0026rsquo;-cyclopentane-1, 1\u0026rsquo;-diyldiphenol (CPDP), 4, 4\u0026rsquo;-(9-fluorenylidene) diphenol and 2,6-dichlorobenzonitrile (DCBN) in the work. The synthesized copolymers were amorphous and found to have good mechanical property. The thermal property and dissolving property were improved well because of the introduction of fluorene group that broken the polymer\u0026rsquo;s local crystal structure. Additionally, the synthesized polymers showed good transmittance with 61.6%-70.4% at 400 nm and 68.3%-76.3% at 450 nm, indicating that they could be potentially applied as the novel heat-resistant optical materials.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by Natural Science Foundation of Sichuan Province (2024NSFSC1847).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eShajie Luo\u003c/strong\u003e: Conceptualization, Investigation, Writing-original draft.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eYuan Wang\u003c/strong\u003e: Data Curation, Investigation, Writing-original draft.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eShuai Zhang\u003c/strong\u003e: Resources, Date validation, Project Administration.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eZhou Jun\u003c/strong\u003e: Literature Survey, Database Construction, Comparative Analysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eJiale Wang\u003c/strong\u003e: Literature Survey, Performance test.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eXiaohan Wang\u003c/strong\u003e: Literature Survey, Performance test.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLishi Jiang\u003c/strong\u003e: Conceptualization, Resources, Supervision, Methodology, Writing-original draft, Writing- review \u0026amp; editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data included in this study are available upon request by contact with the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interest declaration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eDuan Y, Yang H, Liu K, Xu T, Chen J, Xie H, Du H, Dai L, Si C (2023) Cellulose nanofibril aerogels reinforcing polymethyl methacrylate with high optical transparency. 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Polymer 237.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Scheme 1","content":"\u003cp\u003eScheme 1 is available in the Supplementary Files section.\u003c/p\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":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"poly(arylene ether nitrile) copolymers, synthesis, thermal property, optical transmittance","lastPublishedDoi":"10.21203/rs.3.rs-7156844/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7156844/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTwo kinds of novel poly(arylene ether nitrile) copolymers (P-HFD and P-PFD) containing pendant aliphatic ring and fluorene groups were synthesized by 4, 4\u0026rsquo;-cyclohexane-1, 1\u0026rsquo;-diyldiphenol (CHDP) or 4, 4\u0026rsquo;-cyclopentane-1, 1\u0026rsquo;-diyldiphenol (CPDP), 4, 4\u0026rsquo;-(9-fluorenylidene) diphenol and 2, 6-dichlorobenzonitrile (DCBN) in this work. The inherent viscosities of these two copolymers were 0.455 and 0.576 dL g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The copolymers P-HFD and P-PFD exhibited good thermal property, the glass transition temperatures (T\u003csub\u003eg\u003c/sub\u003e) were 202.2-214.9 \u003csup\u003eo\u003c/sup\u003eC, and the weight-loss temperatures (T\u003csub\u003e5%\u003c/sub\u003e) were 421.3-433.5\u0026deg;C. The polymers\u0026rsquo; films had good tensile strengths of 27.3\u0026ndash;38.6 MPa. The result of dissolution experiment showed that the copolymers could be dissolved in some solutions at room temperature, such as NMP, DMF and CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, implying that they had good solubility, they can be processed by the solution method. Additionally, the optical transmittances of these two copolymers were 68.3\u0026ndash;76.3% at 450 nm, indicating that they have potential to be applied as the heat-resistant optical films.\u003c/p\u003e","manuscriptTitle":"Novel transparent poly(arylene ether nitrile) copolymers with pendant aliphatic ring: synthesis and characterization","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-09 17:03:22","doi":"10.21203/rs.3.rs-7156844/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2025-09-03T12:08:18+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-09-03T08:01:18+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Journal of Polymer Research","date":"2025-08-16T21:51:15+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-07-22T12:20:43+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Polymer Research","date":"2025-07-21T20:34:57+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"41dcf2e3-b24d-4819-918e-7ed1a7f7606e","owner":[],"postedDate":"September 9th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-12-15T16:01:59+00:00","versionOfRecord":{"articleIdentity":"rs-7156844","link":"https://doi.org/10.1007/s10965-025-04700-w","journal":{"identity":"journal-of-polymer-research","isVorOnly":false,"title":"Journal of Polymer Research"},"publishedOn":"2025-12-11 15:57:09","publishedOnDateReadable":"December 11th, 2025"},"versionCreatedAt":"2025-09-09 17:03:22","video":"","vorDoi":"10.1007/s10965-025-04700-w","vorDoiUrl":"https://doi.org/10.1007/s10965-025-04700-w","workflowStages":[]},"version":"v1","identity":"rs-7156844","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7156844","identity":"rs-7156844","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}