Regioregular poly(3-alkylthiophene)s (P3AT) are easy to synthesize conjugated polymers with good electrical properties, but they tend to be brittle, limiting their application. To improve their mechanical properties, we investigated incorporating ester groups in the side chains of P3AT six carbons away from the polymer backbone. Two random copolymer series were synthesized: poly(3-alkylthiophene-2,5-diyl)-ran-(3-(6-pentanoatehexyl)thiophene-2,5-diyl), where the alkyl is either n-hexyl (P3HT series) or n-dodecyl (P3DDT series). In both the series, the ester-functionalized side chain had a length similar to that of n-dodecyl and its content was varied from 0 to 100 mol %. The copolymer’s optical, thermal, structural, electrical, and mechanical properties were investigated. The effect of 10–25% ester content on copolymer film aggregation behavior was very different for each series: for the P3HT series, the side chains cocrystallized with the main chains into one crystal structure and behaved as one phase. As a result, incorporation of the longer ester-functionalized side chain greatly affected the thermal, morphological, and mechanical properties. For the P3DDT series, the side chains and main chains crystallize separately, and the n-dodecyl and ester-functionalized side chains appear to cocrystallize together. As a result, the main chain melting temperature decreases only slightly with the ester content, and the mechanical properties were not significantly improved with 10–25% ester. The best combination of mechanical robustness and charge carrier mobility was thus obtained for the P3HT random copolymer with ∼10% ester: a high fracture strain (29 ± 6%) combined with a high tensile strength (3.9 ± 0.6 MPa) resulted in a large toughness (90 ± 30 J/m³). This was achieved while maintaining the same high charge carrier mobility as P3HT of similar molecular weight (0.12 ± 0.01 cm² V^–1 s^–1). Improved ductility was also shown by the thin film-on-elastomer technique. These results demonstrate that side chain modification can optimize both the mechanical and electrical properties of P3ATs when the side chains and the main chain behave as one phase.

中文翻译：

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酯侧链官能化增强聚（3-己基噻吩）的机械性能，同时保持高空穴迁移率

立体规整聚（3-烷基噻吩）（P3AT）很容易合成具有良好电性能的共轭聚合物，但它们往往很脆，限制了其应用。为了提高其机械性能，我们研究了在远离聚合物主链的六个碳原子的 P3AT 侧链中掺入酯基。合成了两个无规共聚物系列：聚(3-烷基噻吩-2,5-二基)-无规-(3-(6-戊酸己基)噻吩-2,5-二基)，其中烷基是正己基(P3HT系列) ）或正十二烷基（P3DDT系列）。在这两个系列中，酯官能化侧链的长度与正十二烷基相似，其含量在0至100 mol%之间变化。研究了该共聚物的光学、热学、结构、电学和机械性能。对于每个系列，10-25% 的酯含量对共聚物膜聚集行为的影响非常不同：对于 P3HT 系列，侧链与主链共结晶成一个晶体结构，并表现为一个相。因此，加入较长的酯官能化侧链极大地影响了热性能、形态和机械性能。对于P3DDT系列，侧链和主链分别结晶，正十二烷基和酯官能化侧链似乎共结晶在一起。因此，主链熔融温度仅随着酯含量的增加而略有降低，并且酯含量为 10-25% 时，机械性能并没有显着改善。因此，含有〜10％酯的P3HT无规共聚物获得了机械强度和载流子迁移率的最佳组合：高断裂应变（29±6％）与高拉伸强度（3.9±0.6MPa）相结合，产生了大的韧性（90±30J/m ³）。这是在保持与相似分子量 (0.12 ± 0.01 cm ² V ^–1 s ^–1 ) 的 P3HT 相同的高载流子迁移率的同时实现的。弹性体薄膜技术还显示出延展性的改善。这些结果表明，当侧链和主链表现为一相时，侧链修饰可以优化 P3AT 的机械和电性能。