Kinetics of Phase Transitions in Multiblock Copolymer Solutions and Gels

建议研究的知识价值。嵌段共聚物溶液在选择性溶剂中表现出丰富的相行为，形成球形或圆柱形胶束的溶液或凝胶。本研究的主要重点是：(1)利用基于同步加速器的时间分辨小角x射线散射（SAXS）来检查这些不同状态之间有序-无序和有序-有序相变的动力学；(2)将实验数据与理论模型和计算机模拟进行比较，以确定这些转变过程中的结构变化，并了解这些转变中涉及的成核和生长机制。要研究的转变包括：(1)从排列在各种立方晶格中的球形胶束到排列在六边形阵列中的圆柱形胶束的转变动力学和相反的过程。（ii）与最终有序态对称不同的中间亚稳或稳定相的存在对无序-有序动力学的影响。（三）其他转变，如立方相之间、片层相和旋转相之间的转变。本研究的两个新特点是：(i)建立一个压力跳跃装置来实现几乎瞬时的转变，（ii）使用嵌段共聚物薄膜作为模板制造纳米级固态器件，例如制造千兆赫纳米机械谐振器。建议研究的更广泛影响。溶剂介导的相互作用与多嵌段共聚物溶液和凝胶的众多工业应用直接相关。该研究项目还将有助于：1。加强研究和教育的基础设施。压力跳跃装置和数据分析程序将提供给同步加速器设施的其他用户。计算机模拟将纳入正在为高级本科和研究生一级的高分子物理学课程学生编制的网络教学包。2. 指导和培训未来科学家，扩大女性在物理科学领域的代表性。这项研究预计将导致两名研究生发表博士论文，并为本科生提供研究机会，无论男女。学生将接受使用国家实验室设备的实践培训，参加地方和国家会议，并与其他大学的合作者密切互动。高中学生将参加波士顿大学的暑期研究项目。与捷克共和国科学家的国际合作是该方案的一个组成部分。这项研究将在国内和国际会议上发表。外展活动。私家侦探将继续通过“新生星期五”、“科学星期六”和“路径计划”等项目，向高中生、大学生和其他普通观众介绍聚合物研究的广泛含义。

Intellectual Merit of the Proposed Research. Block copolymer solutions in selective solvents exhibit a rich phase behavior forming solutions or gels of spherical or cylindrical micelles. The primary focus of this research is (i) to examine the kinetics of order-disorder and order-order phase transitions between these different states using synchrotron based time-resolved small angle x-ray scattering (SAXS), and (ii) to compare the experimental data with theoretical models and computer simulations to determine structural changes during these transitions and understand the nucleation and growth mechanisms involved in these transitions. The transitions to be investigated include: (i) The transformation kinetics from spherical micelles arranged in various cubic lattices to cylindrical micelles ordered in a hexagonal array and the reverse process.(ii) The effects on the disorder-order kinetics due to the presence of an intermediate metastable or stable phase with a different symmetry than the final ordered state.(iii) Other transitions such as between cubic phases, and between lamellar and gyroid phases.Two novel features of this research are (i) to build a pressure jump apparatus to make almost instantaneous transitions, and (ii) to fabricate nanoscale solid state devices using block copolymer films as templates, e.g. to make a gigahertz nanomechanical resonator. Broader Impacts of the Proposed Research. Solvent mediated interactions are directly relevant to the numerous industrial applications of multiblock copolymer solutions and gels. The research project will also contribute to:1. Enhancement of Infrastructure for Research and Education. (i) The pressure jump apparatus and the data analysis programs will be available to other users at Synchrotron facilities. (ii) The computer simulations will be incorporated into a web-based instructional package being developed for students of Polymer Physics courses at the senior undergraduate and graduate level. 2. Mentoring and Training of Future Scientists and Broadening Representation of Women in Physical Sciences. This research is expected to lead to Ph. D dissertations of two graduate students, as well as to provide research opportunities for undergraduates, both men and women. The students will receive hands-on training in the use of facilities at National Laboratories, participate in local and national meetings, and interact closely with the collaborators from other universities. High school students will participate via BU's Summer Research Program. 3. International collaboration with scientists in Czech Republic is an integral part of this program. The research will be presented at National and International conferences.4. Outreach Activities. The P.I. will continue to give presentations to high school and college students and other general audiences about the broad implications of polymer research via programs such as Freshman Fridays, Science Saturdays and the Pathways Program.