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] Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, China; [2] Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China; [3] School of Physical Science & Technology, ShanghaiTech University, 100 Haike Road, Shanghai, 201210, China; [4] Department of Chemistry, University of Toronto, 80 St. George St, Toronto, ON, M5S 3H6, Canada; [5] Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, M5S 3E2, Canada

年份：2022

卷号：14

期号：2

起止页码：137

外文期刊名：Polymer Chemistry

收录：EI(收录号：20225013232327)

语种：英文

外文关键词：Aggregates - Amides - Aromatic compounds - Block copolymers - Molar ratio - Self assembly

摘要：The backbone symmetry of π-conjugated segments is one of the most important structural factors that affect their crystalline behaviors. However, the influence of the backbone symmetry of π-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) (PNIPAM22), that differ in the symmetry of the π-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 π-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 Ln up to 3 μm. Interestingly, BCPs with a symmetric backbone (S-OPE7, S-OPE8 and D-OPE8) exhibit a reverse trend of the dependence of Ln 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 Ln 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. ? 2023 The Royal Society of Chemistry.