Towards the control of surface properties via nanostructured polymeric materials

该研究项目的重点是研究在水介质中端接枝的带电聚合物的动态表面力（摩擦、粘附、表面力的时间和距离依赖）。表面性能将使用表面力仪（SFA）直接测量，这是直接测量表面之间作用的分子力的最可靠的仪器之一。尽管过去已经对不同种类的聚合物承载表面进行了一些使用SFA的研究，但其润滑和粘附机制尚未明确阐明。聚合物性质和环境条件对表面相互作用影响的系统研究缺乏，部分原因是难以控制聚合物接枝密度和接枝层在云母上的稳定性，而云母是SFA测量最可靠的衬底。我们最近开发了不同的方法，允许将聚合物直接共价附着在等离子体活化的云母表面上，并控制接枝密度。我们建议使用双嵌段共聚物（疏水/可电离嵌段）共价附着在云母基质上，最内层疏水直接与云母结合，最外层可电离聚合物在水介质中悬垂。疏水嵌段将在聚合物/云母界面处作为防止水解反应的保护层，这是聚合物解理或滑移的可能位置。通过这些方法，我们的目标是建立端接枝聚合物层的物理和化学性质（厚度、接枝密度、电离程度、弹性、表面粗糙度、化学功能）、环境条件（离子强度、pH值、温度、溶剂条件、压缩、剪切）和聚合物承载表面之间的表面相互作用（摩擦、粘附和力的距离依赖）之间的可靠相关性。

The research program focuses on the investigation of dynamic surface forces (friction, adhesion, time- and distance-dependence of the surface forces) of end-grafted charged polymers in aqueous media. The surface properties will be directly measured using a Surface Forces Apparatus (SFA), being one of the most reliable instruments for the direct measurement of molecular forces acting between surfaces. Although several studies using SFA have been carried out in the past for different classes of polymer-bearing surfaces, the lubrication and adhesion mechanisms are not clearly elucidated. The lack of systematic studies examining the influence of polymer properties and environmental conditions on the surface interactions is in part a result of the difficulty in controlling the polymer grafting density and the stability of grafted layers on mica, which is the most reliable substrate for SFA measurements. We have recently developed different approaches allowing direct covalent attachment of polymers onto plasma activated mica surfaces with a control in the grafting density. We propose to use diblock copolymers (hydrophobic/ionizable block) covalently attached to mica substrates with an innermost hydrophobic layer directly bond to mica and the ionizable polymers as the outermost layer dangling in aqueous media. The hydropbobic block will act as a protective layer against hydrolysis reactions at the polymer/mica interface, a likely location for polymer cleavage or slip. With these approaches, we aim to establish reliable correlations between physical and chemical properties of the end-grafted polymer layers (thickness, grafting density, degree of ionization, elasticity, surface roughness, chemical functionality), environmental conditions (ionic strength, pH, temperature, solvent condition, compression, shear) and surface interactions (friction, adhesion and distance-dependence of the forces) between polymer-bearing surfaces.