NSF-Europe Materials Collaboration: Synthesis, Characterization and Molecular Modeling of Stimulus-Responsive Polymer Brushes on Surfaces

Duke University, Durham NC

Investigators

Abstract

INTELLECTUAL MERITS The objective of the project is to design, fabricate and characterize novel, stimulus-responsive polymer brushes that can be controlled on the molecular length scale. To capitalize on the potential of these stimulus-responsive polymer brush nanostructures, there is a need to understand how molecularscale structural characteristics influence the conformational properties and the hydration dynamics. Furthermore, efficient methods need to be devised to impart this molecular functionality to a variety of surfaces. Model systems with controlled chain length, surface density and surface structure are required in conjunction with theoretical models and experimentally convenient methods to study the conformational mechanics of these polymer systems. The proposed research addresses these needs by tackling three specific aims in the framework of a strong, international collaboration between Duke University, Lund University and the Neutron Research Laboratory (NFL) at Uppsala University. SA 1: Synthesis of new, stimulus-responsive brushes and nanostructures SA 2:Characterization of the effect of molecular architecture on brush conformation and conformational dynamics using QCM-D/ellipsometry and neutron reflection measurements. SA 3: Study of lateral interactions in polymer brush nanostructures through experiments and modeling The results from the proposed activities will contribute significantly to the fundamental understanding of structure-property relationships in stimulus-responsive polymer brushes and nanostructures on surfaces. BROADER IMPACTS AND INTERNATIONAL COLLABORATION In a larger context, the activities outlined in the two interlinked proposals are directed at engineering and controlling the surface chemistry and topography of nanostructured polymeric surfaces in three dimensions. The use of powerful characterization techniques, such as NR, will illuminate the role of molecular architecture on the conformation behavior of copolymer brushes and will likely result in design guidelines for stimulus-responsive polymer brushes. Whereas the proposed combination of QCMD and ellipsometry measurements potentially has more far reaching impact, as it likely can be applied to biomolecular recognition systems, were the combined measurement will reveal insight into the conformational dynamics and the changes in the hydration state upon ligand binding. Molecular modeling will develop tools that can be used to predict and design the conformational response of nanostructured polymeric surfaces. The proposed research offers a great opportunity to further establish and strengthen a research and education linkage between Lund University and Duke University. From the range of activities proposed it is clear that the research is interdisciplinary and clearly addresses fundamental polymer materials phenomena, in addition to novel concepts in materials characterization and synthesis. The scope of the proposed activities is extremely well matched with the combined expertise of the participants. A significant objective of the proposed project is the involvement of student and junior researchers (post docs) in an international research and education experience. The administration of both universities pledged to accredit research and class credits taken by students at the respective partner university. Mutual, extended visits are planned that will strengthen the scientific collaboration but also provide a mechanism to expose students and junior researchers to a significant cultural experience abroad.