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 propertie s in water were investigated by measuring the water uptake of the copolymer s with or without being pretreated with methanol. With ethylene glycol dime thacrylate (EGDM) being used as the crosslinking agent, the obtained AMA/EG DM copolymers, regardless of their inherent hydrophobic nature, were found to be able to swell in water directly. The swelling was negligible in the l ower degree of crosslinking region. However, once it increased to a value b eyond a certain EGDM percentage, the swelling transition occurred, and the water uptake, which was measured by direct contact of the copolymers with w ater for all three kinds of AMA/EGDM copolymers based on methyl MA (MMA), e thyl MA (EMA), and butyl MA (BMA), reached very high values. The direct swe lling of highly crosslinked AMA/EGDM copolymers in water was very fast at t he beginning of the swelling with the swelling rate order of MMA/EGDM > EMA /EGDM > BMA/EGDM, but thereafter it progressed very slowly with most swelli ng being achieved. (C) 2000 John Wiley & Sons, Inc.