Development of Self-Healing Boundary Lubrication Films Using Polymeric Liquids Containing Ionic Functional Groups

利用含离子官能团的聚合物液体开发自修复边界润滑膜[j]: Seong H. kims摘要本研究的重点是开发适用于微机电系统（MEMS）的自修复边界润滑剂。MEMS器件广泛应用于微型卫星、气流控制、传感器、执行器、加速度计、陀螺仪、微波开关、飞机涡轮发动机、无人机等领域。保护MEMS器件免受摩擦、磨损、粘附和其他阻碍性能和缩短使用寿命的破坏性现象的影响，对军事和商业工业构成了重大挑战。边界润滑膜可靠的关键是控制润滑剂分子与基材表面的相互作用。目前工业上研究或使用的大多数边界润滑剂都是通过化学键作用附着在基材表面的。在这种情况下，可以实现润滑层的牢固结合；但无法达到自我修复所需的横向移动能力。通过更弱的物理相互作用（如范德华力）附着在衬底上的简单分子将具有良好的迁移率；但它们不能形成结合润滑涂层。提出的离子聚合物润滑剂方法是在这些强和弱相互作用之间找到平衡。离子聚合物润滑剂将通过它们的离子基团与衬底产生静电相互作用以及范德华相互作用。离子基与衬底之间的静电相互作用将提供润滑剂分子的强附着力。与共价化学键不同，静电相互作用是各向同性的，因此只要电荷中性保持不变，离子对就很容易形成和分离。这将使润滑剂分子在基材表面“结合但可移动”。由于具有横向流动性，润滑油层可以通过从周围区域流动来修复（自愈）磨损区域。提出的研究将提供离子聚合物分子如何与固体底物相互作用和反应以及离子聚合物分子如何吸附在固体表面对机械和摩擦学刺激作出反应的基本理解。这些知识将成为了解离子聚合物分子结构-性能关系的有价值的数据库，并为纳米技术和信息技术的各种应用开发更好的有机涂层材料。该项目还将为研究生提供包括有机化学、表面化学、材料科学、摩擦学和纳米技术在内的多学科培训。新兴纳米工程领域的快速发展迫切需要培养具有这些多学科技能的学生。

Development of Self-Healing Boundary Lubrication Films Using Polymeric Liquids Containing Ionic Functional GroupsPI: Seong H. KimDepartment of Chemical Engineering, The Pennsylvania State UniversityAbstractThe main focus of this research is to develop self-healing boundary lubricants suitable for microelectromechanical systems (MEMS). MEMS devices are widely utilized in miniature satellites, airflow control, sensors, actuators, accelerometers, gyroscopes, microwave switches, aircraft turbine engines, unmanned aerial vehicles, etc. Protecting MEMS devices against friction, wear, adhesion and other destructive phenomena that hinder performance and shorten operational life poses a significant challenge to militaries as well as commercial industries. The key for reliable boundary lubricant film is to control the interaction between the lubricant molecule and the substrate surface. Most of the boundary lubricants currently studied or employed in industries are attached to the substrate surface via chemical bonding. In this case, a strong binding of the lubricating layer can be achieved; but the lateral mobility needed for self healing cannot be attained. Simple molecules attached to the substrate via much weaker physical interactions (such as van der Waals forces) will have a good mobility; but they cannot form bound lubrication coating. The proposed ionic polymer lubricant approach is to find a balance between these strong and weak interactions. The ionic polymer lubricants will have electrostatic interactions with the substrate through their ionic groups as well as van der Waals interactions. The electrostatic interaction between the ionic group and the substrate will provide strong adhesion of the lubricant molecule. Unlike covalent chemical bonding, the electrostatic interactions are isotropic so ionic pairs can easily be formed and dissociated as long as the charge neutrality is conserved. This will make the lubricant molecule "bound yet mobile" on the substrate surface. With the lateral mobility, the lubricant layer can repair (self-heal) the wear region by flowing from the surrounding region. The proposed study will provide fundamental understandings on how the ionic polymer molecule interacts and reacts with solid substrates and how the ionic polymer molecule adsorbed on the solid surface respond to the mechanical and tribological stimuli. This knowledge will be a valuable database to understand the structure-property relationship of ionic polymer molecules and develop better organic coating materials for various applications in nanotechnology and information technology. This project will also give graduate students a multidisciplinary training covering organic chemistry, surface chemistry, material science, tribology, and nanotechnology. The students trained with these multidisciplinary skills are in urgent need for fast growth of newly emerging nano-engineering fields.