Phase Behavior and Properties of ABC Triblock Copolymers

9905008BatesLine ABC三嵌段共聚物的特征是平衡和非平衡形态的光谱复杂，但定义相对较差。这类大分子中的相行为由三个链段-链段相互作用参数、两个独立的组成变量和三种序列可能性(ABC、ACB、BAC)控制，导致了每一种特定的三种聚合物的一系列令人望而生畏的实验配置。本项目将研究ABC嵌段共聚物相行为的两个方面：(I)亚稳态在有序-无序转变附近的作用，以及(Ii)三周期和多连续微结构的稳定范围和各种物理性质。将合成三个用于这些目的的模型体系：ISD(和SID)、ISO(和SiO)和VPE(和PVE)，其中I、S、D、O、P、V和E分别代表聚异戊二烯、聚苯乙烯、聚二甲基硅氧烷、聚环氧乙烷、聚乙丙烯、聚乙烯基环己烷和聚乙烯。阴离子聚合和组成，同时产生相当大(约100克)批次的材料。相行为将通过动态机械光谱、小角X射线散射(SAXS)和透射电子显微镜(TEM)相结合来确定。在第一个推力区，最初无序的三块将冷却到有序区域，并将表征由此产生的有序相序列。我们将对有序-有序转变的动力学进行评估，并将其与囚禁(亚稳态)的发生联系起来。在ISD系统的初步发现的指导下，五连续的核壳内陀螺体相将被绘制为成分(f1和f)的函数，并在第二逆冲区使用SiO和VPE(或PVE)三块进行普适性评估。自洽平均场理论计算将指导材料合成中最有希望的分子参数的选择。微区连续性将通过盐掺杂SiO中的离子导电性来探测，而机械性能将使用包含玻璃(V)、半晶(E)和橡胶(P)块的饱和碳氢三块来评估。嵌段共聚物是一类将化学上不同的聚合物及其相关性质聚集在单一杂化大分子中的材料。这项研究项目将专注于合成三种不同化学结构的聚合物嵌段的新组合，称为ABC三嵌段共聚物，并对所得的微观结构和物理性能进行表征。这些新材料的目标应用包括薄膜和高强度塑料。

9905008BatesLinear ABC triblock copolymers are characterized by a complex, and relatively poorly defined, spectrum of equilibrium and non-equilibrium morphologies. Phase behavior in this class of macromolecules is governed by three segment-segment interaction parameters, two independent composition variables, and three sequence possibilities (ABC, ACB, BAC), leading to a daunting array of experimental configurations for each specified trio of polymers. This project will address two aspects of ABC block copolymer phase behavior: (i) the role of metastability in the vicinity of the order-disorder transition, and (ii) the stability range and various physical properties of triply periodic and multicontinuous microstructures. Three model systems will be synthesized for these purposes: ISD (and SID), ISO (and SIO), and VPE (and PVE) where I, S, D, O, P, V, and E represent poly(isoprene), poly(styrene), poly(dimethysiloxane), poly(ethyleneoxide), poly(ethylenepropylene), poly(vinylcyclohexane), and poly(ethylene), respectively. Anionic polymerization and composition while yielding sizable (ca 100g) batches of material. Phase behavior will be established through a combination of dynamic mechanical spectroscopy, small-angle x-ray scattering (SAXS), and transmission electron microscopy (TEM). In the first thrust area, initially disordered triblocks will be cooled into the ordered regime and the resulting sequences of ordered phases will be characterized. The kinetics of order-order transitions will be assessed and correlated with the occurrence of trapped (metastable) states. Guided by preliminary findings with the ISD system, the pentacontinuous core-in-shell Gyroid phase will be mapped as a function of composition (f1 and fs), and evaluated for universality using SIO and VPE (or PVE) triblocks in the second thrust area. Self-consistent mean-field theory calculations will direct the selection of the most promising molecular parameters for material synthesis. Microdomain continuity will be probed by ionic conductivity in salt-doped SIO while mechanical properties will be assessed using the saturated hydrocarbon triblocks that contain glassy (V), semicrystalline (E), and rubbery (P) blocks.Block copolymers are a class of materials that bring together chemically distinct polymers, and the associated properties, in single hybrid macromolecules. This research project will focus on synthesizing new combinations of three chemically distinct polymer blocks, known as ABC triblock copolymers, and characterizing the resulting microstructures and physical properties. Targeted applications for these new materials include membranes and high strength plastics.