The work outlined in this proposal will investigate the properties of layers of multiblock copolymers that are preferentially adsorbed in a surface through one block, leaving the other block(s) non-adsorbed. The primary objective is to understand how to manipulate the shear properties of these structure-forming layers in order to build polymer-modified surfaces with tailored frictional properties and wear characteristics. Manipulating the frictional properties of polymer-modified surfaces directly impact areas of technology ranging from lubrication and colloid stabilization to novel applications for surface active polymers, including display devices, microvalves, and sensors. The work described in this proposal forms a coherent plan to systematically investigate the impact of solvent quality, shear rate, and layer composition on the dynamic response of various polymer/solvent pairs. The synthesis and characterization of the necessary polymeric materials will be handled through a collaboration with Dr. Jimmy Mays of the University of Alabama at Birmingham. A modified Surface Forces Apparatus housed at Clemson University will be used to directly measure the forces required to slide two polymer coated surfaces laterally past each other. These measurements are done on molecular length scales and therefore, provide information on the molecular-level frictional interactions between the surfaces. The accumulated data on how the dynamic behavior of these interfacial layers are impacted by changes in molecular weight, chain architecture, and solution properties are central to developing the capability to do predictive design of surfaces modified with amphiphilic macromolecules. This work will also result in a more complete body of structure-property data of polymer brushes, which will be generally useful for the developing and engineering of surfaces modified by soft materials.
