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

Maciej Radosz怀俄明州大学“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。“这项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，而且还需要开发新的聚合物材料和新的聚合物加工方法，更有效，更环保。办法是：1）合成新型的接枝和嵌段共聚物，例如聚异丁烯-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），其来自原子转移自由基聚合和活性阴离子聚合，随后部分或完全氢化（对于含聚丁二烯的聚合物）; 2）在微相分离和本体相转变时表征这些聚合物（流体-液体和流体固体）在高压实验中; 3）发展状态方程-基于热力学模型，可以明确地解释和预测接枝和嵌段共聚物的相行为。该研究建立在当前NSF-资助的项目在可结晶聚合物的解决方案中的流体-固体平衡，并在一系列初步的，但有前途的种子实验和计算机模拟使用最新版本的统计关联流体理论（SAFT），如SAFT 1，和最近的Lennard-Jones状态方程与自洽的理论框架的蒸汽，液体，这一研究有助于我们理解大分子结构如何影响具有复杂主链结构的共聚物的相行为。这种理解可以为未来研究具有更复杂结构的其他聚合物的相平衡提供基础，例如三嵌段共聚物和具有双支链（蜈蚣）的接枝共聚物，以及更具预测性的热力学模型。除了在这一领域建立知识库，并为未来的研究奠定基础外，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，理论模型可用于提供超临界流体中接枝或嵌段共聚物的浊点、胶束形成、结晶和熔融的快速预测。需要这样的预测来控制生产线中期望的和不期望的相变。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和活性阴离子聚合。这可能会导致独特的产品和高效，环境友好的过程。更广泛的社会影响的其他例子包括对教育的贡献（研究生和博士后研究人员）和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.