(226bj) Confined Crystallization in Biocompatible Polymer Blend Thin Films

Interest in polymer blend thin film systems is rapidly growing for applications in biotechnology, electronics, and consumer goods. Blend system morphology depends on a number of factors, including the polymer-polymer interaction parameter and the composition of the blend. These factors dictate whether phase separation will occur via nucleation and growth or spinodal decomposition before the morphology coarsens. Polymer crystallinity, the ability to crosslink one of the polymer components, and substrate effects in thin films add complexity to the phase separation process but can lead to distinct and useful results. For example, the ability to tune the mechanical and optical properties of polymer blends by controlling the degree of crosslinking and the extent of crystallinity is beneficial. This project aims to study the interplay between the crosslinking of poly(dimethylsiloxane) (PDMS) and the crystallization of poly(caprolactone) (PCL). At room temperature, which is below the melting temperature of PCL, both processes occur simultaneously. By casting films above the melting temperature of PCL, we can disallow the competition between crosslinking and crystallization. By this method, we create a system wherein upon lowering the temperature the crystallization of PCL is confined by the crosslinked PDMS domains. Thus, we have a system for studying the interplay between crosslinking and crystallization and for examining the effect of 3-dimensional confinement on polymer crystallization morphology and kinetics.