Phase Behavior and Properties of ABC Triblock Copolymers

线性ABC三嵌段共聚物具有复杂且相对不明确的平衡和非平衡形态谱。这类大分子的相行为由三个片段-片段相互作用参数、两个独立的组成变量和三种序列可能性（ABC、ACB、BAC）控制，导致每个特定聚合物三重奏的实验配置令人望而生畏。本项目将解决ABC嵌段共聚物相行为的两个方面：(i)亚稳性在有序-无序转变附近的作用，以及（ii）三周期和多连续微观结构的稳定范围和各种物理性质。为此将合成三种模型体系：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（乙烯基环己烷）和聚（乙烯）。阴离子聚合和组成，同时产生相当大的（约100g）批次的材料。相行为将通过动态力学光谱，小角度x射线散射（SAXS）和透射电子显微镜（TEM）的组合来建立。在第一个冲断区域，最初无序的三块体将被冷却到有序状态，由此产生的有序相序列将被表征。序序跃迁的动力学将被评估，并与捕获态（亚稳态）的发生相关联。在ISD系统的初步发现的指导下，将把五连续核壳相作为组成（f1和fs）的函数进行映射，并在第二个推力区域使用SIO和VPE（或PVE）三区块评估其普遍性。自洽平均场理论计算将指导材料合成中最有前途的分子参数的选择。盐掺杂SIO的微畴连续性将通过离子电导率来探测，而机械性能将通过含有玻璃状(V)、半晶状(E)和橡胶状(P)块的饱和烃三块体来评估。嵌段共聚物是一类将化学性质不同的聚合物及其相关性质结合在一起形成单个杂化大分子的材料。该研究项目将专注于合成三种化学上不同的聚合物嵌段的新组合，称为ABC三嵌段共聚物，并表征所得到的微观结构和物理性质。这些新材料的目标应用包括膜和高强度塑料。

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.