Phase Behavior and Network Morphologies in ABC Triblock Copolymers

合成聚合物在化学工业中占有最大的商业市场之一，其产品范围从垃圾袋到用于精密血管成形术的球囊导管。 聚合物材料必须越来越多地结合联合收割机的多种功能（例如，韧性、硬度、耐溶剂性、渗透性、透明度等），同时优化处理特性和最小化成本。 嵌段共聚物，通过连接两个或多个化学上不同的大分子形成，提供了无与伦比的控制纳米级形态和前景，创造具有竞争力的性能的先进材料。 线性二单体嵌段共聚物（AB，阿坝，ABABA等）在热力学上已得到很好的理解;在通用相图的框架内，从理论和实验两方面建立了四种微相分离态。 三单体三嵌段（ABC、ABCBA等），其提供了更丰富的材料设计组合、相行为和功能性的范围，但明显不太好理解。 该提案针对几个模型ABC三嵌段共聚物系统，战略选择的基本相行为的研究，并作为离子传导膜的发展。 连接ABC三嵌段共聚物理论和实践的最大限制可能是一系列令人生畏的实验变量。 通过苯乙烯（S）、异戊二烯（I）和环氧乙烷（O）的模型阴离子聚合，确定了改变组成和嵌段测序的系统和精确方法，从而能够基于小角X射线和中子散射（SAXS和SANS）、动态力学光谱（DMS）、透射电子显微镜（TEM）和其他方法对相行为进行有组织的评估。 ISO和SIO三嵌段材料将在弱和强偏析限制下进行评估，重点是与领先的理论程序协调确定多连续和三重周期结构。 通过阴离子聚合和催化氢化获得的模型聚烯烃的合成和结构表征将补充这一基本推力，同时为聚合物工业的这一最重要部门贡献新材料。 玻璃态聚（二环己基乙烯）（C）、橡胶态聚（乙基乙烯）（E）和半结晶聚（乙烯）（E）将被配置成互补序列（CEE E、CE E E和E ECE）和模型纳米结构，并评估熔融状态下对剪切的响应和固态下相关的机械性能。 选择性输送特性可与坚固的机械性能、化学稳定性和上级加工性能相结合。 离子传导膜被认为是特别有吸引力的固态电解质和质子传导燃料电池膜的应用。 使用锂掺杂的ISO和SIO三嵌段，将离子电导率确定为形态的函数。 多重连续的形态，如螺旋，预计提供方便的离子传导没有域对齐。 含有酸性部分的新的三嵌段（例如，羧酸或磺酸）将使用阴离子或活性自由基聚合方法制备，通过后聚合官能化增强。 聚（丙烯酸）与氟化聚（丁二烯）和聚（苯乙烯）的组合是初始目标化合物。 这些质子传导材料将通过SAXS、SANS、DMS和TEM表征，从而建立常规非极性嵌段共聚物和含有离子取代基的那些之间的相行为的对应关系

Synthetic polymers command one of the largest commercial markets in the chemical industry with products ranging from ough trash bags to balloon catheters used in delicate angioplaty. Increasingly, polymeric materials must combine multiple functions (e.g., toughness, hardness, solvent resistance, permeability, clarity, etc.), while optimizing processing characteristics and minimizing cost. Block copolymers, formed by joining two or more chemically distinct macromolecules, provide unparalleled control over nanoscale morphology and the prospect for creating advanced materials with competitive properties. Linear two-monomer block copolymers (AB, ABA, ABABA, etc) are well understood thermodynamically; four microphase separated states have been established within the framework of a universal phase diagram, both theoretically and experimentally. Three-monomer triblocks (ABC, ABCBA, etc.), which offer a much richer spectrum of materials design combinations, phase behavior, and functionality, are significantly less well understood. This proposal targets several model ABC triblock copolymer systems, strategically selected for fundamental phase behavior studies, and for development as ion conducting membranes. Perhaps the greatest limitation in connecting ABC triblock copolymer theory and practice is a daunting array of experimental variables. A systematic and precise approach to varying composition and block sequencing through model anionic polymerization of styrene (S), isoprene (I), and ethylene oxide (O) is identified, thereby enabling an organized evaluation of phase behavior based on small-angle X-ray and neutron scattering (SAXS and SANS), dynamic mechanical spectroscopy (DMS), transmission electron miscoscopy (TEM), and other methods. ISO and SIO triblock materials will be assessed in the weak and strong segregation limits with an emphasis on identifying multicontinuous and triply periodic structures in coordination with a leading theoretical program. Synthesis and structural characterization of model polyolefins, obtained by anionic polymerization and catalytic hydrogenation, will compliment this fundamental thrust while contributing new materials to this most important sector of the polymer industry. Glassy poly(dyclohexylethylene) (C), rubbery poly(ethylethylene) (E), and semicrystalline poly(ethylene) (E) will be configured into complimentary sequences (CEE E, CE E E, and E ECE) and model nanostructures and evaluated for response to shear in the melt state and the associated mechanical properties in the solid state.Membranes present an attractive development opportunity for block copolymers. Selective transport characteristics can be combined with robust mechanical properties, chemical stability, and superior processability. Ion conduction membranes are identified as particularly attractive with applications as solid-state electrolytes and proton conducting fuel cell membranes. Ion conductivity will be determined as a function of morphology using lithium doped ISO and SIO triblocks. Multiply continuous morphologies, such as the gyroid, are anticipated to provide facile ion conduction without domain alignment. New triblocks containing acidic moieties (e.g., carboxylic or sulfonic acid) will be prepared using anionic or living free-radical polymerization methods, augmented by post polymerization functionalization. Poly(acrylic acid) in combination with fluorinated poly(butadiene) and poly(styrene) is an initial target compound. These proton-conducting materials will be characterized by SAXS, SANS, DMS, and TEM, thereby establishing the correspondence in phase behavior between conventional non-polar block copolymers and those containing ionic substituents