文献类型：期刊文献

英文题名：Synthesis and living crystallization-driven self-assembly of backbone asymmetric and symmetric π-conjugated oligo(p-phenylene ethynylene)-based block copolymers

作者：Nie, Jiucheng[1,3];Huang, Xiaoyu[1,3];Lu, Guolin[1];Winnik, Mitchell A.[4,5];Feng, Chun[1,2]

机构：[1]Univ Chinese Acad Sci, Shanghai Inst Organ Chem, Chinese Acad Sci, Key Lab Synthet & Selfassembly Chem Organ Funct Mo, 345 Lingling Rd, Shanghai 200032, Peoples R China;[2]East China Univ Sci & Technol, Sch Mat Sci & Engn, Shanghai Key Lab Adv Polymer Mat, 130 Meilong Rd, Shanghai 200237, Peoples R China;[3]ShanghaiTech Univ, Sch Phys Sci & Technol, 100 Haike Rd, Shanghai 201210, Peoples R China;[4]Univ Toronto, Dept Chem, 80 St George St, Toronto, ON M5S 3H6, Canada;[5]Univ Toronto, Dept Chem Engn & Appl Chem, Toronto, ON M5S 3E2, Canada

年份：2023

卷号：14

期号：2

起止页码：137

外文期刊名：POLYMER CHEMISTRY

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000891930400001)】；

基金：The authors are thankful for financial support from the National Science Foundation for Distinguished Young Scholars (51825304), National Natural Science Foundation of China (52122314, 51873229 and 51961145103), the project of Bureau of International Cooperation, CAS (121731KYSB20200006), Youth Innovation Promotion Association of CAS (Y2020062), Shanghai Scientific and Technological Innovation Project (19590750400, 20JC1415400, 21520780100 and 22ZR1475400), Innovation Program of Shanghai Municipal Education Commission (2019-01-07-00-05-E00012) and East China University of Science and Technology (SLD13223004). M. A. W. thanks NSERC Canada for its financial support. The authors thank Dr Kun Cui for his assistance in TEM measurements and the beamline BL16B1 at SSRF for providing the beam time.

语种：英文

摘要：The backbone symmetry of pi-conjugated segments is one of the most important structural factors that affect their crystalline behaviors. However, the influence of the backbone symmetry of pi-conjugated blocks on living crystallization driven self-assembly (CDSA) has not been examined. To explore this effect, we synthesized two pairs of oligo(p-phenylene ethynylene) (OPE)-based BCPs with the same corona-forming block, a 22-mer of poly(N-isopropyl acrylamide) (PNIPAM(22)), that differ in the symmetry of the pi-conjugated block. S-OPE7 and S-OPE8 have one ethynyl between each phenylene unit, whereas D-OPE7 has a second ethynyl group between the OPE3 and OPE4 segments, and D-OPE8 has a second ethynyl group between the two OPE4 segments. The backbone symmetry of the pi-conjugated OPE segment significantly affects both self-seeding and seeded growth behaviors of living CDSA. All of the OPE7- and OPE8-based BCPs exhibit typical self-seeding characteristics, namely that an increase in the annealing temperature of micelle fragments (seeds) in a selective solvent leads to uniform micelles of increasing length, with L-n up to 3 mu m. Interestingly, BCPs with a symmetric backbone (S-OPE7, S-OPE8 and D-OPE8) exhibit a reverse trend of the dependence of L-n on the seed concentration compared to the BCP with an asymmetric backbone (D-OPE7). This might result from the fact that the D-OPE7 segments of seed micelles adopt both H- and J-aggregate modes, but D-OPE8/S-OPE8/S-OPE7 segments adopt only a J-aggregate mode to form micelles. In seeded growth experiments, all of the BCPs with a symmetric backbone (S-OPE7, S-OPE8 and D-OPE8) can efficiently deposit onto the ends of micelles with an OPE9-based core to give uniform segmented comicelles with a linear relationship between L-n and the unimer-to-seed molar ratio. In contrast, seeded growth of backbone asymmetric D-OPE7 BCPs in the presence of seeds of the OPE9-micelles gave only a few segmented comicelles, but a large number of D-OPE7 homo-micelles, owing to obvious self-nucleation/growth.