Limitations and Consequences of Conventional and "Living" Radical Polymerizations in the Synthesis of Side-Chain Liquid Crystalline Polymers

侧链液晶聚合物合成中常规和“活性”自由基聚合的局限性和后果

• 批准号: 9806247
• 负责人: Coleen Pugh
• 金额: $ 23.4万
• 依托单位: University of Akron
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2002-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9806247&HistoricalAwards=false
• 关键词: Limitations; Consequences; Conventional; Living; Radical

9806247 Pugh The objective of this proposat is to synthesize and characterize a series of well-defined side-chain liquid crystalline polymers (SCLCPs) with different molecular architectures in order to determine if mixtures of chemically identical SCLCPs with different types of branching and branching densities are either immiscible or have limited miscibitity, and thereby cause the broad phase transitions often exhibited by SCLCPs synthesized by conventional radical polymerizations. Linear, comb, hyperbranched, and 3-, 6- and 12-arm star poly{11- (4'cyanophenyl- 4"-phenoxy)undecyl acrylate}s will be prepared by atom transfer radical polymerization. The miscibility of the different molecular architectures and its effect on the breadth of their phase transitions will be determined by comparing the thermotropic behavior of each of the molecular architectures with that of their binary blends and unmixed composites. The GPC- determined molecular weights of the polymers will be compared with the molecular weights determined by light scattering measurements and/or MALDI-MS. The star polymers are designed so that the arms can be cleaved subsequent to polymerization in order to compare the molecular weight of the arms with that of the original star polymers, and to determine the uniformity of the arm lengths from their polydispersity in molecular weight. The shape and compactness of the different architectures will be studied by determining how their radius of gyration (light scattering) and intrinsic viscosities scale with molecular weight. Atthough there are extensive experimental results on the solution and melt properties of polymers (eg. polyethylene, polystyrene and polybutadiene) with a variety of well-defined molecular architectures, none have involved polymers with a large side-chain in every repeat unit. The synthesis and solution and solid-state characterization of SCLCPs will therefore greatly expand our fundamentat understanding of the physical chem istry of polymers. This work will also provide the only quantitative kinetic data in the field of SCLCPs; chain transfer constants to polymer will be determined from the Mayo equation and standard kinetic measurements using model chain transfer agents representing a broad range of chemical structures typical of SCLCPs. %%% This research is in the area of novel materials with precisely controlled molecular architectures and liquid-crystalline properties. ***

小行星9806247 本研究的目的是合成和表征一系列具有不同分子结构的明确的侧链液晶聚合物（SCLCP），以确定具有不同类型支化和支化密度的化学性质相同的SCLCP的混合物是否不混溶或具有有限的可聚合性，从而引起通常由常规自由基聚合合成的SCLCP所表现出的宽相变。 采用原子转移自由基聚合法合成了线型、梳形、超支化和3臂、6臂和12臂的星星型聚{11-（4 '氰基苯基-4”-苯氧基）十一烷基丙烯酸酯}。 不同分子结构的相容性及其对相变宽度的影响将通过比较每个分子结构与其二元共混物和未混合复合材料的热致行为来确定。 将GPC测定的聚合物的分子量与通过光散射测量和/或MALDI-MS测定的分子量进行比较。设计星星聚合物，使得臂可以在聚合之后裂解，以将臂的分子量与原始星星聚合物的分子量进行比较，并由其分子量的多分散性确定臂长的均匀性。 不同结构的形状和紧凑性将通过确定它们的回转半径（光散射）和特性粘度如何与分子量成比例来研究。 尽管对聚合物的溶液和熔体性质有大量的实验结果（如：聚乙烯、聚苯乙烯和聚丁二烯），但没有一种涉及在每个重复单元中具有大侧链的聚合物。 因此，SCLCP的合成、溶液和固态表征将极大地扩展我们对聚合物物理化学的基本理解。 这项工作还将提供唯一的定量动力学数据在该领域的SCLCP;链转移常数聚合物将确定从马约方程和标准动力学测量使用模型链转移剂代表了广泛的化学结构的SCLCP的典型。 这项研究是在具有精确控制的分子结构和液晶特性的新型材料领域。 ***