Synthesis of new organic-inorganic hybrids poly[2-hydroxethyl methacrylate (HEMA)-glycidyl methacrylate (GMA)-silica] and their mechanical properties

The presence of low-molecular-weight by-products is a major problem in poly[2-hydroxethyl methacrylate (HEMA)-silica] hybrids prepared using sol-gel synthesis. Low-molecular-weight by-products have a detrimental effect on the optical transparency, and mechanical and storage properties of poly(HEMA-silica) hybrids. To solve this problem, a new sol-gel synthesis procedure was developed to prepare organic–inorganic hybrids. Glycidyl methacrylate (GMA) was used as a comonomer to form poly(HEMA-GMA-silica) (PHGS) hybrids. In addition to forming a copolymer, GMA has two more functions. It facilitates the removal of almost all of the low-molecular-weight by-product molecules formed during sol-gel synthesis and also prevents further condensation of free silanol groups during the polymerization, storage, and use. The mechanical properties of PHGS hybrids were evaluated by using compression testing. The mechanical properties of PHGS hybrids were higher compared to Plexiglas G poly(methyl methacrylate), and the hybrids can be synthesized with reproducible mechanical properties.