Improvement of swelling properties of poly(2-hydroxyethyl methacrylate) hydrogel by means of biomimetic method

Poly(2-hydroxyethyl methacrylates) (PHEMAs) structurally modified by means of polymer blends and ran dom copolymers are intensively studied in order t o improve mechanical properties. It was recently shown that a hydroxyapatit e coating, which should improve the bonding of this biomaterial to the bone , can be obtained by means of the biomimetic method. When PHEMA is submitte d to the biomimetic method, its swelling ratio is improved. This can be asc ribed to the deposition of a silicatic layer, which improves the hydrophili city, on the surface of the internal pores during the first stage of the me thod. This appears to be a valuable result for producing modified PHEMAs wi th improved mechanical properties and good swelling. The experimental resul ts indicate the following: stronger interactions with the water molecules a re set up, an induction period is observed that is linked to the rate of th e reactions occurring at the surface of the glass and the establishment of a convenient concentration of the silicate ions at the external surface of the polymer, and the diffusion of simulated body fluid into the pores is th e limiting stage of the process. (C) 2001 John Wiley & Sons, Inc.