Elucidation of Anomalous Domain Growth in Brush Particle Blends

聚合物纳米复合材料是由分散在聚合物基体中的无机纳米材料组成的材料。聚合物纳米复合材料显示出独特的物理特性，使其成为能源储存和发电、运输或生物医学等领域创新材料技术的平台。这些技术的实现取决于控制材料结构的能力，从而控制其性能。目前缺乏对聚合物和纳米材料成分之间的相互作用及其对材料行为的影响的理解，阻碍了这一点。该项目的目标是开发新的方法来控制聚合物和纳米材料成分之间的相互作用，并利用这些相互作用，使聚合物纳米复合材料的结构和性能可以被刻意控制，以优化性能。这将促进具有改进性能的材料的可扩展和经济制造工艺的发展。该项目将支持两门新的高分子科学与工程课程的教学，并为一名研究生和几名本科生研究人员提供培训。将利用与少数族裔服务机构的教育工作者的合作来支持少数族裔学生的参与。技术摘要：用聚合物链修饰粒子表面有助于控制纳米粒子基材料的相互作用和组装行为。由此产生的电刷颗粒已经作为模型系统出现，以阐明介于经典的“胶体硬球”和“聚合物线圈”极限之间的材料的物理特性，并作为自修复、形状记忆、高k介电材料或热塑性弹性体等领域功能材料开发的平台。该研究项目将对聚合物配体在（纳米）颗粒材料中诱导聚合物相行为的条件进行基本理解。该研究将验证一个假设，即缓慢颗粒扩散的约束效应导致区域生长动力学分裂为两种状态：由接枝链动力学主导的早期“异常”状态和随后由颗粒扩散控制的“规则”生长状态。研究计划分为三个研究重点，重点是合成具有系统变化粒度、聚合程度和接枝链密度的刷状颗粒模型系统；薄膜状态下LCST电刷粒子共混体系的结构演变与分子结构、成分、淬火深度和退火时间的关系；以及用x射线和中子散射分析来解释刷状粒子混合体系在体态下的结构演变。该计划为一名研究生和几名本科生提供跨学科的培训，涉及聚合物和纳米材料以及自组装工艺的关键领域。与少数族裔服务机构的研究人员合作，将促进少数族裔学生和代表性不足群体的参与。该项目将支持两门新的高分子科学和工程课程的教学，以及一门暑期课程，该课程是为访问卡内基梅隆大学的高中生提供的，作为其AP/EA项目的一部分。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL ABSTRACTPolymer nanocomposites are materials that are comprised of inorganic nanomaterials dispersed within a polymer matrix. Polymer nanocomposites display unique physical properties that have rendered them a platform for innovative material technologies in areas such as energy storage and generation, transportation or biomedical. The realization of these technologies is contingent on the ability to control the material’s structure and, thus, its properties. This is hindered by the current lack of understanding of the interactions between the polymer and nanomaterial constituents and their effect on material behavior. The goal of this project is to develop novel methods to control the interactions between polymer and nanomaterial constituents and to harness these interactions to enable polymer nanocomposite materials in which structure and properties can be deliberately controlled to optimize performance. This will promote the development of scalable and economic fabrication processes for materials with improved properties. The program will support the teaching of two new courses on polymer science and engineering and provide training for one graduate student and several undergraduate student researchers. Collaborations with educators at minority serving institutions will be leveraged to support the participation of minority students.TECHNICAL ABSTRACTThe modification of particle surfaces with polymer chains facilitates control of the interactions and assembly behavior of nanoparticle-based materials. The resulting brush particles have thus emerged as model systems to elucidate the physics of materials that are intermediate between the classical ‘colloidal hard sphere’ and ‘polymer coil’ limit and as a platform for the development of functional materials in areas such as self-healing, shape memory, high-k dielectrics, or thermoplastic elastomers. This research project will develop fundamental understanding of the conditions that enable polymer ligands to induce polymer-like phase behavior in (nano)particulate materials. The research will test the hypothesis that the constraining effect of the slow particle diffusion gives rise to the splitting of domain growth kinetics into two regimes: an early ‘anomalous’ regime dominated by the dynamics of grafted chains and a subsequent ‘regular’ growth regime that is governed by particle diffusion. The research plan is organized into three research thrusts that focus on the synthesis of brush particle model systems with systematically varied particle size, degree of polymerization, and density of grafted chains; the characterization of structure evolution of LCST brush particle blend systems in the thin film state as a function of molecular architecture, composition, quench depth and annealing time; and the elucidation of structure evolution of brush particle blend systems in the bulk state using X-ray and neutron scattering analysis. The program provides cross-disciplinary training for one graduate and several undergraduate students in the critical areas of polymer and nanoscale materials as well as self-assembly processes. Collaboration with researchers at minority serving institutions will promote the participation of minority students and underrepresented groups. The program will support the teaching of two new courses on polymer science and engineering as well as a summer course that is offered to high school students visiting Carnegie Mellon University as part of its AP/EA program..This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.