Hypercrosslinked polystyrene microspheres by suspension and dispersion polymerization

Abstract

To determine the influence of particle size on the specific surface area of hypercrosslinked poly(styrene-co-divinylbenzene) (PS) microspheres, two methods were chosen for preparation of particles, suspension and dispersion polymerization. While the former method produced hundred micrometer-sized PS-S microspheres, the latter yielded PS-D particles of ca. 1-μm size. Dispersion copolymerization of styrene (St) and divinylbenzene (DVB) in ethanol was stabilized by (hydroxypropyl)cellulose (HPC) and initiated with dibenzoyl peroxide (BPO). Monodisperse 1.4-μm PS-D microspheres were prepared only in the presence of 3.6 wt% HPC. All microspheres were chloromethylated with chloromethyl methyl ether (CMME), chloromethyl ethyl ether (CMEE) or chloromethyl octyl ether (CMOE) to investigate the effect of the chloromethylation agent on the specific surface area of microspheres. Chloromethylated microspheres were hypercrosslinked in 1,2-dichloroethane (DCE) in the presence of a Lewis acid (SnCl4). The effects of the crosslinker (DVB) and DCE/microsphere ratio on properties of the product were studied. The specific surface area, pore volume and pore size distribution of the microspheres were analyzed by dynamic desorption of nitrogen, cyclohexane regain and mercury porosimetry.