Role of Chain Architecture on the Properties of Linear and Star Chain Thin Film Polymer Systems

聚合物表面与基材或外部环境之间的界面处的相互作用通常是导致局部聚合物结构变化的原因，例如单体“堆积”密度和链组织顺序。 在纳米级厚度的聚合物膜中，物理性质的变化，包括共混物的传输性质、平均玻璃化转变温度、润湿性质和相稳定性，与这种相互作用有关。理论和模拟表明，界面相互作用是敏感的大分子的结构。具体而言，星星形大分子表现出更高的倾向与界面相互作用。 它们遭受较低的构象熵处罚比他们的线性链类似物，当吸附在界面。本研究的目的是发展的限制（厚度和几何）和大分子功能（每分子的臂数）的星的动力学，润湿，玻璃化，相平衡和老化的线性链/多臂星星高分子共混物的作用的理解。该研究是通过使用模拟和补充实验工具，包括X射线光子相关光谱，介电光谱，中子散射，原子力显微镜和透射电子显微镜technology. NON-PERFICALPolymer薄膜的应用，包括保护和功能涂层，有机电子器件中的活性材料组件，和信息存储。聚合物薄膜的性能和可靠性受到其表面与基材或与外部环境之间形成的界面处的相互作用的影响。 最近变得明显的是，聚合物分子的结构，无论是线性链还是星形（即，多于一个链连接到中心分支点），对界面相互作用的强度具有显著影响。 这个项目的目标是了解聚合物分子的结构，包括连接到分支点的链的数量，如何影响聚合物薄膜的物理性质。 这项研究的成功将对聚合物用于润湿和粘附，保护和功能涂层以及其他活性技术的使用产生影响。 这项研究将涉及不同的合作者群体，从高中和本科生到研究生，他们将被引入研究，并可能成为追求科学或技术事业的动力。

TECHNICAL Interactions at interfaces between polymer surfaces and substrates or the external environment are typically responsible for changes to the local polymer structure, such as monomer "packing" densities and chain organizational order. In polymer films of nanoscale thickness changes to physical properties, including transport properties, average glass transition temperatures, wetting properties and phase stability of blends, are associated with such interactions. Theory and simulations suggest that the interfacial interactions are sensitive to the architecture of the macromolecules. Specifically, star shaped macromolecules exhibit a higher propensity to interact with interfaces. They suffer lower conformational entropic penalties than their linear chain analogs, when adsorbed at interfaces. The goal of this research is to develop an understanding of the role of confinement (thickness and geometrical) and of the macromolecular functionality (number of arms per molecule) of stars on the dynamics, wetting, vitrification, phase equilibra and aging in linear chain/multi-arm star macromolecule blends. The research is accomplished through the use of simulations and complementary experimental tools that include X-ray photon correlation spectroscopy, dielectric spectroscopy, neutron scattering, atomic force microscopy, and transmission electron microscopy techniques.NON-TECHNICALPolymer thin films are used in applications that include protective and functional coatings, active material components in organic electronic devices, and information storage. The performance and reliability of a polymer film is influenced by interactions at interfaces formed between its surfaces and a substrate, or with the external environment. It recently became apparent that the architecture of the polymer molecule, whether it is a linear chain or star-shaped (i.e. more than one chain attached to a central branch point, has a significant impact on the strength of the interfacial interactions. The goal of this project is to understand how the architecture of the polymer molecules, including the number of chains connected to the branch point, affects the physical properties of polymer films. The success of this research will have implications on the use of polymers for wetting and adhesion, protective and functional coatings, and other active technologies. This research will involve a diverse group of collaborators, from high school and undergraduate to graduate students, who will be introduced to research and may become motivated to pursue scientific or technological careers.