The synthesis of nonporous poly(isobutyl methacrylate) microspheres by suspension polymerization technique and investigation of their swelling properties

Poly(isobutyl methacrylate) (PiBMA) microspheres with different crosslinkin g densities were synthesized by suspension polymerization technique in aque ous medium and their characterization and swelling behaviors in different s olvents were investigated. PiBMA spheres with a 800- to 1500-mum-diameter r ange were obtained by using benzoyl peroxide (BPO) as polymerization initia tor, 1/5 ratio of monomer/water in volume, tricalcium phosphate (TCP), and poly(N vinyl-2-pyrrolidone) (PVP) as suspension stabilizer with 350 rpm sti rring rate in nitrogen atmosphere. The influence of type and amount of cros slinking agent on the swelling properties and diffusional behavior, diffusi on coefficient, and network properties of the spheres were examined in pent ane, hexane, heptane, and gasoline. Dynamic swelling behaviors of crosslink ed spheres were determined by measuring the diameter of the sphere as a fun ction of time by an optical microscope. Swelling behaviors and network prop erties were found to be dependent on the diameter, crosslinking density of the sphere, and crosslinking agent and solvent. The results of this study i ndicate that the crosslinked PiBMA microsphere can be swollen in gasoline v ery well and retains a high ratio (1500% of its volume) of gasoline in thei r structure. (C) 2002 John Wiley & Sons, Inc.