Heteroarm Star-Branched Copolymers

该赠款由该部门的聚合物项目共同资助 材料研究和有机合成计划 化学部。 含x臂的杂臂星星聚合物 单体A的n-x臂和单体B的n-x臂应表现出不寻常的 偏析和相间现象。 活体连接反应 将用于合成A2 B2星星聚合物， 聚苯乙烯和聚二烯臂，以及一种新的通用 荧光标记化学将被用于连接 芘、蒽和萘基团的末端， 怀里 合成了一系列杂臂星星型共聚物， 结构将被用来探索其独特的动态和 平衡性能在固态，在熔体中， 溶液 在孤立的环境中臂间相互作用的后果 杂臂恒星将从速率和平衡进行评估， 大环化，从分子的激基缔合物发射推断， 其中两个臂在其自由端带有芘或萘基团， 形接头. 不同类型臂间的区别 在半稀释溶液、熔体和 用杂臂星选择性地测定固态 标记用于研究准分子发射或福斯特速率 转移 孤立的异臂星的动力学，以及它们的 扩散在浓溶液和熔体，将确定 使用脉冲梯度自旋回波核磁共振。

This grant is jointly funded by the Polymer Program in the Division of Materials Research and the Organic Synthesis Program in the Division of Chemistry. Heteroarm star polymers containing x arms of monomer A and n-x arms of monomer B should exhibit unusual segregation and interphase phenomena. Living linking reactions will be used to synthesize A2B2 star polymers composed of polystyrene and polydiene arms, and a new general fluorescent-labeling chemistry will be utilized to attach pyrene, anthracene, and naphthalene groups at the termini of the arms. A series of heteroarm star copolymers with well-defined structures will be used to explore their unique dynamic and equilibrium properties in the solid state, in the melt, and in solution. The consequences of interarm interactions in isolated heteroarm stars will be assessed from the rates and equilibrium for macrocyclization, as deduced from excimer emission by molecules in which two arms bear pyrene or naphthalene groups at their free ends. Discrimination between the various types of interarm interactions that can occur in semidilute solution, melts, and in the solid state will be determined with heteroarm stars selectively labeled for the study of excimer emission or the rate of Forster transfer. The dynamics of isolated heteroarm stars, and their diffusion in concentrated solutions and melts, will be determined using pulsed-gradient spin-echo NMR.