How a Small Change of Oligo(p-phenylenevinylene) Chain Length Affects Self-Seeding of Oligo(p-phenylenevinylene)-Containing Block Copolymers
How a Small Change of Oligo(p-phenylenevinylene) Chain Length Affects Self-Seeding of Oligo(p-phenylenevinylene)-Containing Block Copolymers
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低聚（对亚苯基亚乙烯基）链长的微小变化如何影响含低聚（对亚苯基亚乙烯基）的嵌段共聚物的自种晶
DOI：
10.1021/acs.macromol.0c00068
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发表时间：
2020-03-10
期刊：
影响因子：
5.5
通讯作者：
Feng, Chun
中科院分区：
文献类型：
--
作者：
Cui, Yinan;Wang, Zhiqin;Feng, Chun
具有π-共轭结晶链段的共聚物的自接种已被认为是活性结晶驱动自组装以产生具有半导体核的均匀纤维状纳米结构的通用方法。核形成块的结构，影响自引晶过程的最重要的因素之一，尚未被系统地研究。我们合成了三种结构明确的OBPVn-b-PNIPAM [OBPV = oligo（2，5-dibutyloxy-1，4-phenylenevinylene），PNIPAM = poly（N-isopropyl acrylamide），n = 4，5，6]嵌段共聚物，以及相同的形成冠状结构的PNIPAM嵌段。这里，下标表示每个嵌段的重复单元的数目。]然后，我们详细研究了它们的自组装行为，特别是在自播种条件下。OBPV 4-b-PNIPAM 49在甲醇中形成短纤维状胶束，但在乙醇和异丙醇中聚集成不明确的结构。相反，OBPV 5-b-PNIPAM（49）和OBPV 6-b-PNIPAM（49）在这些溶剂中形成宽度均匀、长度约1-2 μ m的纤维状胶束。OBPV 4-b-PNIPAM（49）在甲醇中自接种形成具有宽长度分布的纤维状胶束。虽然通过OBPV 5-b-PNIPAM（49）和OBPV 6-b-PNIPAM（49）在甲醇中的自接种可以产生具有受控长度的均匀纤维状胶束，但是对于OBPV 6-b-PNIPAM（49）仅获得具有约94 nm长度的短纤维状胶束。OBPV 5-b-PNIPAM（49）和OBPV 6-b-PNIPAM（49）在乙醇中的自接种产生受控长度的均匀胶束。有趣的是，注意到OBPV 6-b-PNIPAM（49）的种子片段对溶解的抗性比OPV 5-b-PNIPAM（49）在这些溶剂中的抗性强得多，即使OBPV 6仅比OBPVs多一个亚苯基亚乙烯基单元。这些结果表明，OBPV链长显著影响OBPV基共聚物的自接种行为。有趣的是，具有OBPV和OBPV 6的异质核的均匀共胶束可以通过OBPV 5-b-PNIPANI（49）和OBPV 6-b-PNIPAM（49）的混合物的自接种来制备，这表明协同自接种在制造具有异质核的半导体纳米纤维中的巨大潜力。
Self-seeding of copolymers with a pi-conjugated crystalline segment has been considered to be a versatile approach of living crystallization-driven self-assembly to generate uniform fiber-like nanostructures with a semiconducting core. The structure of a core-forming block, one of the most important factors affecting the self-seeding process, has not yet been systematically investigated. We synthesized three well-defined diblock copolymers of OBPVn-b-PNIPAM [OBPV = oligo(2,5-dibutyloxy-1,4-phenylenevinylene), PNIPAM = poly(N-isopropyl acrylamide), with n = 4, 5, 6, and the same corona-forming PNIPAM block. Here, the subscripts represent the number of repeat units of each block.] We then examined in detail their self-assembly behavior, especially under self-seeding conditions. OBPV4-b-PNIPAM 49 formed short fiber-like micelles in methanol, but aggregated into ill-defined structures in ethanol and in isopropanol. In contrast, both OBPV5-b-PNIPAM(49) and OBPV6-b-PNIPAM(49) formed fiber-like micelles of uniform width and with lengths of about 1-2 mu m in these solvents. Fiber-like micelles with a broad length distribution were formed by self-seeding of OBPV4-b-PNIPAM(49) in methanol. Although uniform fiber-like micelles of controlled lengths can be generated via self-seeding of OBPV5-b-PNIPAM(49) and OBPV6-b-PNIPAM(49) in methanol, only short fiber-like micelles with a length of about 94 nm were obtained for OBPV6-b-PNIPAM(49). Self-seeding of OBPV5-b-PNIPAM(49) and OBPV6-b-PNIPAM(49) in ethanol gave uniform micelles of controlled lengths. It is interesting to note that the resistance of seed fragments of OBPV6-b-PNIPAM(49) toward dissolution is much stronger than that of OPV5-b-PNIPAM(49) in these solvents, even though OBPV6 has only one more phenylene vinylene unit than OBPV s . These results demonstrate that the OBPV chain length significantly affects the self-seeding behavior of OBPV-based copolymers. Intriguingly, uniform comicelles with a heterogeneous core of OBPV, and OBPV6 can be prepared by self-seeding of a mixture of OBPV5-b-PNIPANI(49) and OBPV6-b-PNIPAM(49), indicative of the great potential of synergistic self-seeding in the fabrication of semiconducting nanofibers with a heterogeneous core.