Tuning Adhesion by Surface Modification with Mixed Polymer Brushes

聚合物-固体界面的粘附对于从微电子到航空工业的许多应用都是非常重要的。对于永久粘合和可逆粘合，基材的化学成分和形态必须得到完美的控制。该项目旨在开发新一代基于化学非均质可切换聚合物薄膜的自适应表面，这些薄膜与固体衬底共价结合，从而以良好控制和可复制的方式修改其表面化学。这种薄膜是最近由两种不相容的聚合物材料制成的，它们一端系在衬底上（混合聚合物刷）。这些混合电刷根据不同的环境发生相偏析，从而导致形貌和表面能态的显著改变。该项目旨在研究混合刷的切换现象对这种表面与粘合剂形成的界面强度的影响。这些表面对于调整软胶粘剂的粘合性能特别有用。这类粘合剂因其低毒性和易于使用而在工业和医药领域获得越来越多的兴趣。了解这种粘合剂的主要要求，可以在不同的基材上产生可逆、快速和容易的粘合。我们计划在受控环境中制备具有适应性和可切换粘合性能的聚合物薄膜。混合刷状层将采用“接枝到”和“接枝自”的方法制备。通过椭偏、XPS、XPEEM、FTIR/ATR、接触角和AFM测量，对具有自适应和可切换粘附的功能薄膜进行定量表征。这种表面改性对粘合剂和摩擦性能的影响将通过利用原子力显微镜的纳米断裂测试和弹性体粘合剂的探针测试来研究。德国集团在薄膜制备、表面化学和表面表征领域提供专业知识，法国集团在机械测量和粘合剂性能表征领域提供专业知识。

Adhesion at polymer-solid interfaces is of great importance for numerous applications from microelectronics to aircraft industry. It is essential, for permanent as well as for reversible adhesion, that the substrate's chemical composition and morphology is perfectly controlled. The project aims at the development of a new generation of adaptative surfaces based on chemically heterogeneous switchable thin polymer films, which covalently bond to a solid substrate, modifying therefore its surface chemistry in a well-controlled and reproducible way. Such films were recently fabricated from two incompatible polymer materials tethered at one end to the substrate (mixed polymer brushes). Those mixed brushes undergo phase segregation depending on environment resulting in a remarkable switching of morphology and surface energetic state. The project aims to study the influence of the switching phenomenon of mixed brushes on the strength of the interface which such a surface can form with an adhesive. These surfaces will be particularly useful to tune the adhesive properties of soft adhesives. This class of adhesives is gaining increasing interest in industry and medicine for its low toxicity and ease of use. Knowing the main requirements for such adhesives provides the capability to generate reversible, fast and easy adhering bonds to different substrates. We plan to prepare polymer films with adapting and switchable adhesive properties in a controlled environment. The mixed brush-like layers will be fabricated with "grafting to" and "grafting from" methods. Functional thin films for adapting and switchable adhesion will be quantitatively characterized with ellipsometry, XPS, XPEEM, FTIR/ATR, contact angle and AFM measurements. The consequences of this surface modification on adhesive and frictional properties will be investigated by a nano fracture test utilizing AFM and a probe test for elastomeric adhesives. The German group provides expertise in the area of film preparation, surface chemistry and surface characterization and the French group contributes expertise in the area of mechanical measurements and characterization of adhesive properties.