2-Hydroxypropylmethacrylate based mono- and bifunctional gel beads prepared by suspension polymerization

Spherical and swellable gel beads in the size range 35-200 mu m were prepar ed by suspension polymerization of 2-hydroxypropylmethacrylate (HPMA). In t he proposed method, a mixture of cyclohexanol and octanol was used as a dil uent phase dispersed in an aqueous medium including poly(vinyl pyrrolidone) (PVP) as the stabilizer. The polymerization was initiated within the organ ic phase including the monomer and the crosslinker (ethylene glycol dimetha crylate) by an oil soluble initiator benzoyl peroxide. Spherical and swella ble gel beads carrying both hydroxyl and carboxyl functional groups were al so prepared by suspension copolymerization of HPMA and a water soluble como nomer (methacrylic acid). For this purpose, the suspension polymerization m ethod proposed for HPMA was modified by using poly(vinyl alcohol) as a stab ilizer instead of PVP. The effect of initiator concentration, polymerizatio n temperature, monomer/diluent ratio, crosslinker concentration, stirring r ate on yield, average size, size distribution, and carboxyl content of the HPMA based gel beads, were investigated. The swelling characteristics of th e gel beads were defined. (C) 2000 Society of Chemical Industry.