MICROPHASE SEPARATED SEMIINTERPENETRATING POLYMER NETWORKS FROM ATACTIC POLYSTYRENE AND METHACRYLATES - A NOVEL ROUTE

A new route towards the formation of micro-phase separated semi-interpenetrating polymer networks (semi-IPN's) is described for the system atactic PS in methacrylates. It comprises the arrest of spinodal decomposition of an aPS solution by thermoreversible gelation (vitrification) of the polymer-rich phase. After low-temperature UV-polymerization and crosslinking of the methacrylate, the phase separated structure is preserved at room temperature. Thus the steps of morphology formation and polymerization are separated. The demixing and gelation behaviour of solutions of atactic PS in several n-alkyl and branched methacrylates was studied. Gelation temperatures were found to be determined by the position of the demixing curves along the temperature axis and thereby the intersection points with the glass transition-concentration curve of plasticized PS. At polystyrene concentrations of 2 and 5 wt% a bicontinuous microphase separated morphology could be obtained with domain sizes of 0.2-0.5-mu-m.