Solvation Studies of Responsive Polymers in Solution and at Surfaces

ARRA声明：该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。技术概述：本提案将研究聚合物微观结构，溶剂添加剂和溶液组分对溶液和表面低临界溶液温度（LCST）现象的影响。提出的研究将使用溶液状态光散射分析云点行为，主要使用体相微分析自动数字熔点仪来并行研究小尺度样品。其他分析技术也将被采用。例如，标记聚合物的荧光光谱将探测在可见相分离开始和结束之前和之后发生的聚合物聚集事件。我们将研究小分子和大分子共溶质对多种具有结构异构重复单元的聚合物的LCST的影响，以确定离子、共价和大分子共溶质如何影响给定聚合物的LCST。在这些溶液状态研究中产生的结构和化学信息将用于开发新的刺激响应表面，这些表面可以在超疏水性和亲水性之间可逆地变化。这些表面的物理性质也将被研究，以确定聚合物接枝的水化变化是否会改变表面的机械性能，如粘弹性和附着力。这些表面可以用一系列的分析方法来研究。这些表面结构的变化将以薄膜纳米复合材料的形式响应于大块水组分中的溶质，并将在适当的情况下进行实时监测。非技术总结：这项工作将研究刺激反应大分子溶解度的分子细节。这将主要涉及研究大分子的温度依赖性溶解度如何随着溶液中其他物质的存在而变化。这些研究将包括水性聚合物溶液的研究和固体表面含聚合物涂层的研究。这种反应性聚合物溶解度研究很重要，因为这种材料是反应性催化剂和传感器的组成部分。聚合物的溶解度和温度依赖性在决定蛋白质和酶的稳定性和活性方面也至关重要。将大分子溶液行为的研究扩展到包括表面，将有助于更好地理解表面的响应性润湿性和“智能”表面的设计。这种“智能”表面有潜力成为自清洁的新材料，具有可控的附着力，或具有不同的表面摩擦。这些研究将有更广泛的影响，包括在研究实验室和课堂上的本科和研究生教育。向工业界、主要是本科院校和国际场所的听众作报告，在校外传播结果，将宣传这些研究的结果。本研究中使用的化学方法将发展成实验，并将在大一化学课程中使用，以教育学生大分子水合作用中焓和熵的结果。将促进国际研究合作，并将与欧洲、中国和卡塔尔的团体开展项目。

ARRA STATEMENT:This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).TECHNICAL SUMMARY: This proposal will examine the effect of polymer microstructure, solvent additives and solution components on lower critical solution temperature (LCST) phenomena both in solution and at surfaces. The studies proposed will use solution state light scattering analyses of cloud point behavior mostly using a bulk phase microanalytical automated digital melting point apparatus to study small scale samples in parallel. Other analytical techniques will be employed too. For example, fluorescence spectroscopy with labeled polymers will probe polymer aggregation events that occur before and after visible phase separation starts and ends. The effects of small molecule and macromolecular co-solutes on LCSTs of a variety of polymers with structurally isomeric repeating units will be carried out to determine how ionic, covalent and macromolecular co-solutes affect a given polymer's LCST. The structural and chemical information generated in these solution-state studies will then be used to develop new sorts of stimuli-responsive surfaces that reversibly change between being superhydrophobic or hydrophilic. Such surfaces physical properties will also be studied to determine if the hydration changes of the polymer grafts alter surface mechanical properties such as viscoelasticty and adhesion. These surfaces with be studied using a battery of analytical methods. The surface structural changes associated with reorganization of these surfaces that will be in the form of thin film nanocomposites in response to solutes in bulk water component will be followed, and, in suitable cases, will be monitored in real time.NON-TECHNICAL SUMMARY: This proposed work will study the molecular details of stimuli-responsive macromolecular solubility. This will primarily involve studies of how a macromolecule's temperature-dependent solubility changes in response to the presence of other species in solution. These studies will include studies of aqueous polymer solutions and studies of polymer-containing coatings on solid surfaces. Such responsive polymer solubility studies are important because such materials are components of responsive catalysts and sensors. Polymer solubility and the temperature dependence of polymer solubility is also critically important in determining the stability and activity of proteins and enzymes. Extending studies of solution behavior of macromolecules to include surfaces will lead to a better understanding of responsive wettability of surfaces and the design of 'smart' surfaces. Such 'smart' surfaces have potential as new materials that are self cleaning, that have controllable adhesion, or that have varied surface friction. These studies will have broader impacts that include both undergraduate and graduate education in the research laboratory and classroom. Extramural dissemination of results in presentations to audiences in industry, at predominantly undergraduate institutions, and at international venues will publicize the results of these studies. The chemical methodology used in this research will be developed into experiments that will be used in freshman chemistry courses to educate students about the consequences of enthalpy and entropy in macromolecule hydration. International research collaborations will be fostered and will involve programs with groups in Europe, China, and Qatar.