含有聚对苯撑乙烯撑类链段的两嵌段共聚物的合成及结晶驱动自组装行为的研究

Semiconducting polymers have attracted a great deal of interest for their promise to produce inexpensive and flexible LEDs, transistors and photovoltaic cells. Among various semiconducting copolymers, poly(phenylenevinylenes) (PPV) and its derivatives has been one of most widely studied semiconducting polymers due to its electrical and optical properties. The control over molecular packing of conducting polymer and the morphology of the active layer is required for the optimization of these devices. Recent work shows that the length and composition of cylindrical micelles formed by some crystalline copolymers could be controlled through the crystallization-driven self-assembly and seeded-growth of crystalline copolymers. Furthermore, some certain part of the multi-component co-micelles formed by crystallization-driven seeded-growth process could selectively be functionalized and some super-micelles could form through the self-assembly of multi-component co-micelles in some selective solvents. In this project, considering the excellent crystallinity of PPV and its derivatives, we are going to prepare a series of copolymers containing PPV's derivatives segment. Through the study of the crystallization-driven self-assembly and seeded-growth of these copolymers, the controlling over the packing of PPV's derivatives not only could be realized, the selectively functionalization and super-micellization of multi-component also should be achieved. This project will provide a new avenue for improving the performance of PPV based materials and other crystalline polymers through the crystallization driven self-assembly.

导电高分子在发光材料、太阳能电池等领域具有诱人的应用前景，对它的相关性能研究一直是一个热点。由于PPV及其衍生物所具有的良好的光电性能，它是研究最为深入的导电高分子之一。调控这类高分子的堆砌和微观拓扑结构是提高其性能的一个重要手段。最近研究表明，含有结晶性嵌段的聚合物，其结晶诱导的高分子自组装以及"种子增长"胶束化行为不仅可以调控其形成的棒状胶束的长度和组成，还可以实现多组分棒状胶束的选择性修饰和超胶束自组装。由于PPV及其衍生物具有良好的结晶性，我们拟合成一系列具有不同结构的含有PPV衍生物的嵌段聚合物，通过研究这类聚合物结晶驱动的自组装，期望实现这类聚合物结晶驱动的"种子增长"胶束化行为，在此基础上实现对PPV类聚合物有序可控地堆砌，并且实现对含有PPV嵌段的多组分胶束选择性的修饰以及超胶束自组装。本项目的实施将为利用自组装提高PPV类聚合物以及相关结晶聚合物的性能开辟一条新的途径。

聚对苯撑乙烯撑(poly(p-phenylenevinylene))及其衍生物是一类典型的共轭高分子。由于其所具有的良好的光电性能，它在电致发光材料、太阳能电池材料、传感器、微波吸收材料以及防静电材料等领域具有广泛的应用。如何在纳米尺度上对这类共轭高分子基的纳米材料在结构和功能进行精确调控是共轭高分子基精细纳米功能材料制备中的难点之一。 我们通过对含有对苯撑乙烯撑寡聚物(OPV)的共聚物结构进行优化，提高OPV之间强的p-p堆砌作用和结晶性，将结晶驱动自组装中的“自晶种”(self-seeding)和“种子增长” (seeded growth)过程应用于以OPV为核的纳米纤维状胶束的精确制备中。基于温度诱导的“自晶种”(self-seeding)，通过改变退火温度，在纳米尺度上精确地调控单分散的纳米纤维状胶束的长度。在此基础上，我们还系统研究了聚合物的结构以及实验条件等因素对“自晶种”组装行为的影响。基于“种子增长”(seeded growth)的结晶驱动自组装，通过改变所加入的聚合物和原有溶液中种子胶束的比例，在纳米尺度上精确地调控单分散的纳米纤维状胶束的长度。更为重要的是，由于“种子增长”(seeded growth)和活性聚合过程相类似，他们还可以在纳米尺度上精确调控所制备的单分散纳米纤维状胶束壳层的组成(J. Am. Chem. Soc. 2017, 139, 7136.)。另外，我们利用聚2-乙烯基吡啶链段具有良好的络合金属的能力，制备了一系列负载有功能纳米粒子的纳米纤维。总之，该研究发展了一种通过对苯撑乙烯撑寡聚物的结晶驱动自组装，从而在纳米尺度上精确调控以对苯撑乙烯撑寡聚物为核的单分散纳米纤维的长度和组成的新策略，有望应用于其他可结晶的共轭高分子体系来制备长度和结构精确可控的纳米纤维材料。