Adhesion, Friction and Lubrication in Polymeric and Biological Systems

非技术综述：黏附、摩擦和润滑的基础研究对于理解细胞黏附、胶体稳定、纳米模塑、纳米制造和药物输送非常重要。许多生物系统显示出优异的粘附性和润滑性；例如，人类关节中的软骨可以承受十个大气压的压力，并且具有非常低的摩擦系数。这些生物材料的一个独特特征是它们由带有带电基团的生物大分子组成。该奖项支持研究生在现代分析和计算方法方面的研究和培训，这些方法应用于生物和聚合物系统中的粘合、摩擦和润滑。这项研究的主要目的是对静电相互作用在生物和仿生聚合物系统中的粘合和摩擦中的作用有一个基本的了解。这将通过理论和计算技术相结合的协同办法来实现。理论模型的预测将在计算机模拟中进行测试，并通过与美国实验研究小组的合作进行实验验证。该项目将对材料设计的科学技术产生影响，使其具有所需的粘接和润滑性能。该项目还将为研究生和本科生参与前沿研究提供特殊机会。对学生的指导融入了研究的方方面面。研究生将与物理、化学或化学工程专业的本科生以及有才华的高中生合作。这一经验将为他们未来的STEM职业生涯做好准备。技术摘要：许多生物系统显示出优异的粘附性和润滑性。这些生物材料的一个独特特征是它们由具有可电离基团的生物大分子组成。在水溶液中，这些材料的性质受到电离基团之间的静电相互作用、与周围介质的相互作用以及溶液的离子强度的影响。这项研究的主要目的是了解静电相互作用在生物和聚合物系统中粘附性和润滑性方面的具体作用。这将通过结合分子动力学模拟、自洽场计算和标度分析来实现。这些技术将被用来开发覆盖软骨表面的糖蛋白-胶原网络层的润滑模型。理论和模拟将被用来研究体系的静态和动态性质作为盐浓度、溶液pH、带电基团比例、分子结构和滑动速度的函数。这项研究的首要目标将是在纳米尺度上了解介电不连续对粘着和摩擦的影响。理论模型的预测将在计算机模拟中进行测试，并通过与美国实验研究小组的合作进行实验验证。该项目将对材料的科学和技术产生影响，这些材料的设计具有所需的粘附性和润滑性。拟议的研究还将为研究生和本科生参与尖端研究提供特殊机会。辅导学生被整合到拟议研究的每一个方面。拟议的研究结果将被纳入研究生水平的课程，以及一个关于含离子聚合物的新的专题课程。

NON-TECHNICAL SUMMARY:Fundamental studies of adhesion, friction and lubrication are important for understanding cell adhesion, colloidal stabilization, nanomolding, nanofabrication, and drug delivery. Many biological systems demonstrate superior adhesion and lubrication properties; for example, cartilage in human joints can withstand pressures on the order of ten atmospheres and have remarkably low friction coefficients. A unique feature of these biomaterials is that they consist of bio-macromolecules with charged groups. This award supports research and training of graduate students in modern analytical and computational methods with application to adhesion, friction and lubrication in biological and polymeric systems. The main goal of this research is to develop a fundamental understanding of the role of electrostatic interactions in adhesion and friction in biological and biomimetic polymeric systems. This will be achieved through a synergistic approach combining theoretical and computational techniques. The predictions of the theoretical models will be tested in computer simulations and verified experimentally through collaboration with experimental research groups in the US. This project will have an impact on science and technology of materials design with desired adhesive and lubricating properties. This project will also provide special opportunities for involvement of graduate and undergraduate students in cutting-edge research. Mentoring of students is integrated into every aspect of the research. Graduate students will work with undergraduate students in physics, chemistry or chemical engineering, as well as with talented high school students. This experience will prepare them for future STEM careers.TECHNICAL SUMMARY:Many biological systems demonstrate superior adhesion and lubrication properties. A unique feature of these biomaterials is that they consist of bio-macromolecules with ionizable groups. In aqueous solutions, properties of these materials are influenced by electrostatic interactions between ionized groups, by interactions with surrounding media, and by the ionic strength of the solutions. The main goal of this research is to understand the specific role of electrostatic interactions on adhesion and lubrication in biological and polymeric systems. This will be achieved through a combination of molecular dynamics simulations, self-consistent field calculations, and scaling analysis. These techniques will be used to develop a model of lubrication for the glycoprotein-collagen network layer covering cartilage surfaces. Theory and simulations will be used to study the system's static and dynamic properties as a function of salt concentration, solution pH, fraction of charged groups, molecular architecture, and sliding velocity. The overarching objective of this research will be to understand the effect of dielectric discontinuity on adhesion and friction at the nanoscale. The predictions of the theoretical models will be tested in computer simulations and verified experimentally through collaboration with experimental research groups in the US. This project will have an impact on the science and technology of materials designed with desired adhesive and lubricating properties. The proposed research will also offer special opportunities for involvement of graduate and undergraduate students in cutting-edge research. Mentoring students is integrated into every aspect of the proposed research. The results of the proposed research will be incorporated into graduate level courses as well as into a new special topics course on ion-containing polymers.