Rigid Hypercrosslinked Polystyrene Networks with Unexpected Mobility

Abstract

Due to manifold application possibilities in important modern technologies, three-dimensional polymeric networks attract attention of many researcher groups. Simultaneously, many attempts have been made to describe theoretically the behavior of polymeric networks. Generally accepted modern theories predict that networks acquire a noticeable flexibility only in the case that the distance between two neighbor junction points exceeds the length of chain segments. Therefore, slightly or moderately crosslinked polymers, only, should be in position to swell with thermodynamical1y good solvents. With the degree of crosslinking rising, the high elasticity properties of a network should gradually disappear, the glass transition temperature being shifted rapidly toward the temperature region of thermal decomposition of the material. These fundamental properties are well documented with examination results of many types of polymeric networks, in particular, that of crosslinked polystyrene. Indeed, conventional styrene-diviny1benzene (DVB) copolymers are known ^1,2 to lose their ability to swell with solvents or acquire high elastic state on heating at a DVB content exceeding 15%..