Phase Behavior of Block and Graft Styrene Copolymers in Near Critical and Supercritical Solvents

嵌段和接枝苯乙烯共聚物在近临界和超临界溶剂中的相行为。本研究的总体目标是了解嵌段和接枝苯乙烯共聚物在可压缩流体中的相行为，如近临界和超临界溶剂和单体。这种理解不仅需要改进现有的制造工艺，而且需要开发更有效、更环保的新聚合物材料和新聚合物加工方法。本研究是实验和热力学模拟的综合。方法将是：1)通过原子转移自由基聚合和活阴离子聚合，然后部分或完全加氢（含聚丁二烯的聚合物）合成新型接枝和嵌段共聚物，如聚异丁烯-g-聚苯乙烯（PIBg-PS）、聚丁二烯-g-聚苯乙烯（PBD-g-PS）和聚丁二烯-b-聚苯乙烯（PBDb-PS）；2)在高压实验中对这些聚合物进行微相分离和整体相变（流-液和流-固）表征；3)开发基于状态方程的热力学模型，可以明确地解释和预测接枝共聚物和嵌段共聚物的相行为。这项研究建立在一个目前由美国国家科学基金会资助的关于可结晶聚合物溶液中的流固平衡的项目上，以及一系列初步但有前途的种子实验和计算机模拟，这些实验和模拟使用了最新版本的统计关联流体理论（SAFT），例如SAFT1，以及最近的具有自一致理论框架的Lennard-Jones状态方程，用于蒸汽，液体和固体相。该研究有助于我们进一步了解大分子结构如何影响具有复杂骨架结构的共聚物的相行为。这样的理解可以为未来研究其他结构更复杂的聚合物的相平衡提供基础，例如三嵌段共聚物和双分支接枝共聚物（蜈蚣），以及更具有预测性的热力学模型。除了建立该领域的知识库，并播种未来的研究之外，该项目还可能对现有和未来的商业聚合物技术产生更广泛的影响。例如，理论模型可用于在超临界流体中提供云点、胶束形成、结晶和接枝或嵌段共聚物熔化的快速预测。这样的预测是控制生产线中理想的和不理想的相变所必需的。该模型本身也可用于优化超临界流体中的高级聚合方案，如ATRP和活阴离子聚合。这可能导致独特的产品和高效，环保的过程。更广泛社会影响的其他例子包括对教育（研究生和博士后研究人员）的贡献，以及扩大代表性不足群体的参与。

Maciej RadoszUniversity of Wyoming"Phase Behavior of Block and Graft Styrene Copolymers in Near Critical and Supercritical Solvents."The overall goal of this research is to understand the phase behavior of block and graft styrene copolymers in compressible fluids, such as near critical- and supercritical solvents and monomers. Such understanding is needed not only to improve existing manufacturing processes, but also to develop new polymeric materials and new polymer processing approaches that are more efficient and more environmentally acceptable.This research is a synthesis of experiment and thermodynamic modeling. The approach would be to: 1) synthesize novel graft and block copolymers, such as polyisobutene-g-polystyrene (PIBg-PS), polybutadiene-g-polystyrene (PBD-g-PS), and polybutadiene-b-polystyrene (PBDb-PS) from atom transfer radical polymerization and living anionic polymerization followed by partial or complete hydrogenation (for polymers containing polybutadiene); 2) characterize these polymers upon microphase separation and bulk phase transitions (fluid-liquid and fluid solid) in high-pressure experiments; and3) develop equation-of-state-based thermodynamic models that can explicitly account for and predict the phase behavior of graft and block copolymers.The research builds on a current NSF-funded project on fluid-solid equilibria in solutions of crystallizable polymers, and on a series of preliminary but promising seed experiments and computer simulations using recent versions of Statistical Associating Fluid Theory (SAFT), such as SAFT1, and a recent Lennard-Jones equation of state with self-consistent theoretical framework for vapor, liquid, and solid phases.This research could enhance our understanding of how the macromolecular structure affects the phase behavior of copolymers with complex backbone architecture. Such understanding could provide a basis for future research on phase equilibria for other polymers with even more complex architecture, such as triblock copolymers and graft copolymers with double branches (centipede), and more predictive thermodynamic models. In addition to building a knowledge base in this area, and seeding future research, the project could have a broader impact on the existing and future commercial polymer technology. For example, the theoretical model can be used to provide rapid predictions of cloud points, micelle formation, crystallization, and melting of graft or block copolymers in supercritical fluids. Such predictions are needed to control desirable and undesirable phase transitions in production lines. The model itself can also be used to optimize advanced polymerization schemes in supercritical fluids, such as ATRP and living anionic polymerization. This may lead to unique products and efficient,environmentally benign processes. Other examples of a broader social impact includecontributions to education (graduate students and post-doctoral researchers) and to broadening participation of underrepresented groups.