Structural modification of poly(2-hydroxyethyl methacrylate)-silica hybrids utilizing 3-methacryloxypropyltrimethoxysilane

In this paper, our goal is to improve the understanding of structural control of hybrid materials synthesized from mixtures of tetramethoxysilane, water and poly(hydroxyethyl methacrylate) (PHEMA). To evaluate the effect of primary interactions between organic and inorganic components, the bonding agent 3-methacryloxypropyltrimethoxysilane (MTMOS) was used in the preparation of the copolymer P(HEMA-co-MTMOS) prior to sol-gel reactions. The presence of MTMOS prevented crack formation and macroscopic phase separation, though the formation of larger fluctuating composition domains with increasing PHEMA content was detected by an increase in scattering of ultraviolet and visible wavelength radiation. According to thermogravimetry, the degree of silica condensation was not measurably affected by the presence of PHEMA contents less than or equal to 40%. Glass transition temperatures (T-g) of hybrids, determined by differential scanning calorimetry, increased for the larger silica contents and mainly with the addition of MTMOS, which indicates loss of chain mobility due to its greater interpenetration within silica network in hybrids with bonding agent. (C) 2002 Elsevier Science B.V. All rights reserved.