Understanding Structure and Response in Thermally-Responsive Block Copolymer Assemblies

技术综述：响应性聚合物组件在包括药物输送、传感和催化在内的一系列应用中显示出巨大的前景。这些体系的关键是聚合物的开发，这些聚合物在不同大小和结构的组件之间经历快速、可预测和可逆的变化。对于涉及在聚合物小泡中包裹其他物种的应用，开发更有效的包裹方法也是非常重要的。为了应对这些挑战，PI和他的同事们以前已经制备了温度响应型ABC三嵌段共聚物，以聚氧乙烷(PEO)为亲水嵌段，以聚(N-异丙基丙烯酰胺)为温度响应性嵌段，以聚异丙烯为可交联性疏水嵌段，形成在临界温度附近经历大小和形状变化的组件，然而，在高温下将小组件(直径20 nm的胶束)重组为较大的组件(直径100 nm的囊泡)需要数周时间。最近，与聚丁二烯-环氧乙烷响应性嵌段相关的共聚物在没有水的情况下有较弱的链间相互作用，被发现在几个小时内发生了显著的结构转变。这项研究将探索这一假说，即在脱水状态下减弱链间相互作用是提高组装转化率的关键。这项研究将进一步加深对这些嵌段共聚体系及其潜在应用的了解。具体地说，PI和同事们将研究新的亲水-响应-疏水三嵌段共聚物，进一步探索可能的结构转变(例如胶束到蠕虫状胶束)，更深入地研究组装转变过程的动力学，并对嵌段共聚物组装进行包封和释放研究。对这些新型响应系统的进一步研究为扩展和改变基于聚合物的纳米结构的应用提供了潜力。非技术摘要：纳米尺寸的聚合物分子组装在从治疗癌症和其他疾病到开发新的传感设备等一系列应用中显示出巨大的前景。这项研究将进一步加深我们对聚合物组件的理解，这些组件被设计为在暴露于热或其他刺激时在尺寸和形状上经历特定的变化。通过这样做，它将为未来使用这些材料的应用奠定基础，在这些应用中，对刺激的反应可以与特定的应用相结合，例如释放化疗药物或检测特定分子。这项研究将由研究生和本科生进行，作为他们科学培训的一部分，并将涉及与石溪大学、布鲁克海文国家实验室和英国华威大学的其他研究人员的合作。PI将通过纽约州立大学路易斯·斯托克斯少数族裔参与联盟(SUNY LSAMP)计划招募本科生参与化学系的研究。这项工作的结果将在国际上参加的科学会议上公布，参与该项目的博士生将建立一个网站/博客，通过该网站/博客，他们将能够向公众传达他们对该项目和科学研究人员生活的看法。

TECHNICAL SUMMARY:Responsive polymer assemblies show great promise in a range of applications, including drug delivery, sensing, and catalysis. Crucial to the elaboration of these systems is the development of polymers that undergo rapid, predictable, and reversible changes between assemblies with different sizes and structures. For applications involving encapsulation of other species within polymer vesicles, the development of more efficient encapsulation methods is also of great importance. To meet these challenges, the PI and co-workers have previously prepared temperature-responsive ABC triblock copolymers with poly(ethylene oxide) (PEO) as a hydrophilic block, poly(N-isopropylacrylamide) as a thermoresponsive block, and polyisprene as a cross-linkable hydrophobic block, which form assemblies that undergo large changes in size and shape around a critical temperature, however the reorganization of small assemblies (micelles of 20 nm diameter) into larger assemblies (vesicles of 100 nm diameter) at elevated temperatures was found to take several weeks. Recently, related copolymers with poly(butylene oxide-stat-ethylene oxide) responsive blocks, in which there are weaker interchain interactions in the absence of water, were found to undergo significant structural transformations within several hours. This research will probe the hypothesis that weakening interchain interactions in the dehydrated state is critical to increasing assembly transformation rate. This research will further the understanding of these block copolymer systems and their potential applications. Specifically, the PI and co-workers will investigate new hydrophilic-responsive-hydrophobic triblock copolymers, further probe possible structural transformations (e.g., micelle-to-worm-like micelle), more deeply investigate the kinetics of the assembly transformation process, and carry out encapsulation and release studies with block copolymer assemblies. The further study of these novel responsive systems offers the potential to expand and transform the applications of polymer-based nanostructures.NON-TECHNICAL SUMMARY:Nanometer-sized assemblies of polymer molecules show much promise in a range of applications, from the treatment of cancer and other diseases to the development of new sensory devices. This research will further our understanding of polymer assemblies that are designed to undergo specific changes in size and shape upon exposure to heat or other stimuli. In doing so, it will lay the groundwork for future efforts to use these materials in applications where the response to stimulus can be coupled to a specific application, such as release of a chemotherapy agent or the detection of specific molecules. This research will be carried out by graduate and undergraduate students as part of their scientific training and will involve collaboration with other researchers at Stony Brook University, Brookhaven National Laboratory, and Warwick University (UK). The PI will work through the State University of New York Louis Stokes Alliance for Minority Participation (SUNY LSAMP) program to recruit undergraduate students to participate in research in the chemistry department. Results of this work will be presented at internationally-attended scientific meetings and the PhD students involved in the project will maintain a website/blog through which they will be able to communicate their reflections on the project and the life of a scientific researcher to the general public.