Swelling of porous copolymers based on alkyl methacrylate esters in water

Porous copolymers based on alkyl methacrylate esters (AMA) were prepared in the presence of toluene as the inert diluent, and their swelling properties in water were investigated by measuring the water uptake of the copolymers with or without being pretreated with methanol. With ethylene glycol dimethacrylate (EGDM) being used as the crosslinking agent, the obtained AMA/EGDM copolymers, regardless of their inherent hydrophobic nature, were found to be able to swell in water directly. The swelling was negligible in the lower degree of crosslinking region. However, once it increased to a value beyond a certain EGDM percentage, the swelling transition occurred, and the water uptake, which was measured by direct contact of the copolymers with water for all three kinds of AMA/EGDM copolymers based on methyl MA (MMA), ethyl MA (EMA), and butyl MA (BMA), reached very high values. The direct swelling of highly crosslinked AMA/EGDM copolymers in water was very fast at the beginning of the swelling with the swelling rate order of MMA/EGDM > EMA/EGDM > BMA/EGDM, but thereafter it progressed very slowly with most swelling being achieved.