Role of Polymer Brush Dynamics on Adhesion via Complementary Binding Events

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TECHNICAL SUMMARY: Polymer chains at solid or fluid interfaces have an enormous spectrum of applications in technologies as varied as colloidal stabilization, lubrication, adhesion and the synthesis of biocompatible interfaces. The ability of chains to display such interfacial activity is dependent not only on their static structure but also on their dynamic behavior. Highly sensitive binding and adhesion experiments will be developed to assess the dynamic conformational sampling of grafted polymer chains and the impact of chain dynamics on complementary adhesion. Utilizing the Surface Forces Apparatus technique (SFA), which has angstrom resolution in distance and 10 pN resolution in force, the absolute distance at which binding occurs between functionalized polymer chains and complementary receptor groups will be determined as a function of time allowing the dynamic motion of the chains to be measured. The rate of cross-bridge formation is a direct measure of the spatial exploration of the end of the grafted polymer chains. The adhesion energy will be related to the interaction potential of the individual bonds including biological recognition molecules, surface concentration, physical properties of the chains, and structure of the grafted polymer layer. The experimental methodology will be applied to a wide variety of grafted architectures (including monodisperse, bimodal and polydisperse) providing quantitative measures of chain dynamics and adhesion. The overall goal of these studies is to rationally design smart interfacial polymer-films with tunable adhesivity. NON-TECHNICAL SUMMARY: Polymer chains at solid or fluid interfaces have an enormous spectrum of applications in technologies as varied as colloidal stabilization, lubrication, adhesion and the synthesis of biocompatible interfaces. The ability of polymers to display such interfacial activity is dependent not only on their static structure but also on their dynamic behavior. This work will develop and utilize novel experiments to directly measure the dynamic motion of polymer chains. The experimental methodology will be applied to a wide variety of polymer architectures providing quantitative measures of chain dynamics and adhesion. The overall goal of these studies is to rationally design smart interfacial polymer-films with tunable adhesivity. The research actively involves graduate and undergraduates students as the key research participants. A new educational program entitled Polymers Theyre Everywhere will be developed by the principal investigator for use in a high school level, summer outreach program to minority students.