Stimuli responsive surfaces: Dynamic control of surface energy, nanotopography, porosity and bioadhesion

Stimuli responsive surfaces are currently of interest many fundamental studies and industrial applications. This study describes new methodologies to synthesize smart surfaces with dynamically controllable surface energy, nanotopography, porosity and bioadhesive properties. The approaches are based on hybrid materials that combine inorganic supports to provide rigidity and environmentally sensitive polymers to provide dynamic functionality. Two approaches for forming such hybrid materials are presented. In the first approach, atom transfer radical polymerization (ATRP) has been successfully used to synthesize stimuli responsive microparticles with controlled molecular release properties. The pore size and hydrophilicity of hybrid materials can be easily modulated by changing of the conformation of the responsive polymers through change in the environmental temperature. ATRP is demonstrated to be a promising method of surface modification, especially for small pores. Long radical lifetime and slow propagation rate ensure uniform coverage and narrow polydispersity of polymer molecular weight. In the second approach, a sol-gel process with hybrid precursors and a coupling agent provides a versatile method to incorporate stimuli responsive polymers into rigid silica matrices. Surfactant templating techniques can be used to easily control the porosity in the materials. In both approaches, the size of pores, the surface morphology (therefore, wettability), and effective interfacial energy can be tuned at the nanometer scale using responsive polymers. The studies described in the dissertation have created new directions towards new materials for separations, adsobents, sensors, custom designed filters, and other advanced applications.