Studies of porous polymer gels. III. Swelling behavior of porous poly(methacrylic acid) gels



Further studies of porous suspension copolymers of methacrylic acid and divinylbenzene (DVB) are reported. The qualitative structure model of the copolymers proposed previously is used to interpret the ion-exchange properties, sorption of water and aqueous sodium chloride solution, swelling, and neutralization rate. It is proposed that the close to ideal NON-SOL methacrylic acid–divinylbenzene copolymers are composed of rigid microgels and lightly crosslinked poly(methacrylic acid). The latter swollen in water gives the gel, which tends to occupy the accessible space in the copolymer bead together with macropores detectable in the dry state. For the copolymers studied, the DVB content, 5.0 and 9.1% by weight, affects the rigid portion dimension and the extent of swelling of the whole bead, while the expansion of linear chains is determined by the distance between microgels.