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

这项研究的目的是建立一个充满活力的项目，合成各种定义明确的、共轭的两嵌段共聚物，并研究它们的物理性质。共轭两嵌段共聚物具有棒-棒结构，其行为将不同于棒-线圈类型的共聚物。这些共轭两嵌段共聚物是电活性聚合物的新结构。这项工作的主要目的是了解棒棒型两嵌段共聚物将表现出的电子和结构性质。为了探索这些性质，本提案概述了共轭嵌段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各不相同。将合成一系列官能化的共轭低聚物，从低聚硫苯、低聚亚苯基乙烯到低聚苯并烯烃。将研究这些低聚物的电子和物理性质，作为它们与两嵌段共聚物(或共低聚物)进行比较的数据库。得到的几种低聚物将被偶联，形成具有不同共轭长度和电子性质的两嵌段共聚物。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，以找出其分子堆积和相行为的原理。具有不同氧化还原性能的共聚物将被耦合起来，以探索诸如光学吸收和发光以及光导和电导等电光性能。具有富电子嵌段和缺电子嵌段的共聚物将被功能化，其中亲水侧基连接到第一个侧基，疏水部分连接到第二个侧基。这些嵌段共聚物将被用来制备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。这些嵌段共聚物有望通过相分离组装成纳米连续的结构域，这将被探索用于光伏效应。对两嵌段共聚物的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性质的实验。

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.