Electron-beam derived polymeric cryogels

Abstract

In this study we publish a novel attempt to macroporous, polymeric cryogels (MPCs) by electron-beam (EB) initiated free radical crosslinking polymerization of (meth)acrylates in frozen aqueous media. The EB-process is an environmentally benign fast process (radiation and reaction time about 10–20 min) which allows the initiator-free polymerization of double-bond containing monomers. The MPCs were thoroughly characterized by swelling experiments, SEM, detailed XPS studies, DMA, Hg intrusion porosity and ESEM. The processes during the reaction were studied using ESR experiments. The influences of the reaction parameters like dose, radiation time, freezing conditions, chemical composition and (meth)acrylate concentration on the properties of the MPCs were investigated. The MPCs were synthesized in situ in capillaries or in tubes up to a diameter of 25 mm. The porous structure of the MPCs is mainly controlled by the freezing temperature and the macromonomer/crosslinker concentration and consists of large interconnected pores in the range of 10–70 μm. The crosslinker concentration directly affects the stiffness and the T_g of the materials. The MPCs were successfully modified with poly(allylamine hydrochloride). This straightforward method provides a toolbox for the synthesis of manifold MPCs from various unsaturated substances in large quantities and scale.