Synthesis and Characterization of Conjugated Diblock Copolymers (Co-Oligomers)

本研究旨在建立一个强有力的项目，以合成各种定义良好的共轭二嵌段共聚物，并研究它们的物理性质。共轭二嵌段共聚物具有棒-棒结构，其行为与棒-线圈型共聚物不同。这些共轭二嵌段共聚物是电活性聚合物的新结构。这项工作的主要目标是了解棒状-棒状二嵌段共聚物将表现出的电子和结构特性。为了探究这些性质，本提案概述了共轭块的各种组合及其合成方法。这些组合从具有不同的两亲性到具有不同的电子性质。将合成一系列功能化共轭低聚物，从低聚噻吩、低聚苯乙烯到低聚苯乙烯。这些低聚物的电子和物理性质将被研究作为与二嵌段共聚物（或共低聚物）比较的数据库。所得的几种低聚物将偶联形成具有不同共轭长度和电子性质的二嵌段共聚物。由于这些嵌段共聚物可以进行相分离并形成自组装，因此将对自组装进行微观研究，以发现其分子堆积和相行为背后的原理。具有各种氧化还原性能的共聚物将被耦合，以探索电光性能，如光吸收和发光，光导和导电性。具有富电子嵌段和缺电子嵌段的共聚物将被官能化，亲水的侧基连接到第一个，疏水的部分连接到后者。这些嵌段共聚物将被用于制备L-B薄膜，由于其内置的分子“P-N”结，其分子电子效应非常有趣。这些嵌段共聚物预计将经过相分离组装成纳米连续结构域，这将用于光伏效应的探索。对二嵌段共聚物可能应用的研究包括它们在光电器件中的应用，如光伏和电致发光器件、分子电子元件和光开关。还提出了探索导致这些应用的特性的实验。

This research is aimed at establishing a vigorous project to synthesize various well-defined, conjugated diblock copolymers and to investigate their physical properties. A conjugated diblock copolymer possesses a rod-rod structure and will behave differently than rod-coil types of copolymers. These conjugated diblock copolymers are new architectures of electroactive polymers. The main goal of this work is to understand the kind of electronic and structural properties that the rod-rod types of diblock copolymers will exhibit. To probe these properties, various combinations of conjugated blocks and their synthetic approaches are outlined in this proposal. These combinations vary from having different amphiphilic properties to having different electronic properties. A series of functionalized conjugated oligomers, ranging from oligothiophenes and oligophenylenenvinylenes to oligophenlylenes, will be synthesized. The electronic and physical properties of these oligomers will be investigated as the database for their comparison with diblock copolymers (or co-oligomers). Several of the oligomers obtained will be coupled to form diblock copolymers with various conjugation lengths and electronic properties. Since these block copolymers can undergo phase separation and form self-assembly, microscopic studies of the self-assemblies will be carried out to find the principles underlying their molecular packing and phase behaviors. Copolymers with various redox properties will be coupled to explore electro-optic properties such as optical absorption and luminescence, and photoconductivity and electrical conductivity. Copolymers with an electron-rich block and an electron-deficient one will be functionalized with a hydrophilic side group attached to the first and hydrophobic moiety attached to the latter. These block copolymers will be sued to prepare L-B films, which are very interesting for their molecular-electronic effects due to their built-in molecular "P-N" junction. These block copolymers are expected to undergo phase separations to assemble into nanometer-continuous domains, which will be explored for photovoltaic effect.The investigation of possible applications of the diblock copolymers includes their use in electro-optic devises, such as photovoltaic and electroluminescent devices, molecular-electronic components, and optical switching. Experiments to explore the properties leading to those applications are also proposed.