Synthesis of bioactive HEMA-MPS-CaCl2 hybrid gels: effects of catalysts in the sol-gel processing on mechanical properties and in vitro hydroxyapatite formation in a simulated body fluid.

We investigated synthetic conditions for the fabrication of bioactive hybrid gels from monomers of 2-hydroxyethylmethacrylate (HEMA) and 3-methacryloxypropyltrimethoxysilane (MPS) in combination with CaCl(2), at a starting molar ratio of HEMA: MPS : CaCl(2) of 9 : 1 : 1. Hydroxyapatite formation, essential to show bone bonding, was observed on the HEMA- MPS-CaCl( 2) hybrid gels with the added catalysts NH(3) or HCl with a molar ratio to MPS of 0.1, but not on the hybrid gel with HCl at a molar ratio to MPS of 1. The mechanical properties of the gels were dependent on the catalysts, which may affect the microstructures that develop during sol-gel processing.