Effect of shell thickness on the temperature-sensitive property of core-shell composite polymer particles

Core-shell composite polymer particles having temperature-sensitive shell were prepared by seeded emulsion copolymerization of dimethylaminoethyl methacrylate and ethylene glycol dimethacrylate (EGDM) with 0.14 mu m-sized polystyrene seed particles according to our previous article. In this article, the effects of crosslinking density and thickness of the shell on the temperature-sensitive property were studied. Two series of composite particles, one with various EGDM contents in the shell and the other with various shell contents, were prepared for this study. The composite particles at the EGDM content of 3 wt % with the shell content of 47 wt %, showed the maximum swelling and deswelling phenomena at temperatures, respectively, below and above the lower critical solution temperature. The adsorption and desorption behaviors of low molecular weight cationic emulsifier and biomolecules were dependent on the shell content. In almost all cases, the adsorption/desorption behavior reached to the maximum variations at the shell content of 17 wt %. (C) 1996 John Wiley & Sons, Inc.