SYNTHESIS AND CHARACTERIZATION OF A POLY(METHYL METHACRYLATE-ACRYLIC ACID) COPOLYMER FOR BIOIMPLANT APPLICATIONS

This paper describes the development of a new crosslinked poly(methyl methacrylate-acrylic acid) copolymer for potential applications in bon e implants. This copolymer, comprising hydrophobic and hydrophilic com ponents, has been designed to provide small amounts of controllable sw elling strains at saturation when exposed to an aqueous saline environ ment. The volume fraction of the hydrophobic methyl methacrylate monom er to the hydrophilic acrylic acid monomer strongly influenced the swe lling behavior of the copolymer. Two different cross-linking agents, a llyl methacrylate and diethylene glycol dimethacrylate, were evaluated for their effectiveness in cross-linking and limiting the saturated s welling levels. The influences of the amounts of crosslinking agents a nd other processing parameters on the swelling behavior of the copolym er were studied using differential scanning calorimetry measurements, solubility tests, and swelling measurements in saline solutions. These measurements provided a good understanding of the structure of the co polymer, the effectiveness of the crosslinkers, the swelling mechanism s in this system, and the factors that strongly affect the swelling we ight gain levels in this copolymer. (C) 1997 John Wiley & Sons, Inc.