Studies of porous polymer gels. II. Structure and porosity of moderately crosslinked poly(methacrylic acid) gels



The porosity of suspension copolymers of methacrylic acid (MA) and divinylbenzene (DVB) has been studied. The copolymers were prepared both directly from monomer blends and with toluene or n-octane as inert diluents. The pore volume and radii of pores were larger for copolymers containing 5.0% of DVB than those for copolymers containing 9.1% of DVB. The volume and radii of pores increased with increasing diluent content, but the effect of n-octane was more pronounced than that of toluene. Based on considerations of monomer reactivities and copolymer-diluent and copolymer-unreacted monomer interactions, the following model of structure of MA and DVB copolymers has been proposed: The copolymers are composed of microgels interconnected into a rigid skeletonlike structure, surrounded by lightly crosslinked and unentangled poly(methacrylic acid) chains.