Microgels are chemically crosslinked submicron polymer particles prepared by emulsion polymerization. This water-based process leads to a product that is an aqueous colloidal dispersion. The microgel particles can be designed to swell with changes in solvent, temperature and / or pH. By varying the crosslink density and co-monomer ratios the degree and rate of particle swelling are readily controlled. This paper describes the preparation and properties of microgels prepared by copolymerization of the monomer 4-vinylpyridine (shown below) and styrene. Recipes used are also shown (4VP = 4-vinyl pyridine, ST = styrene, DVB = divinylbenzene crosslinker).