Synthesis, structure and bioactivity of pHEMA/SiO2 hybrids derived through in situ sol–gel process

Abstract

A novel procedure to synthesize poly(2-Hydroxyethylmethacrylate)-silica blend hybrids is presented. Methacrylate monomers bearing an alkoxysilyl unit, prepared by Michael addition of 2-Hydroxyethylmethacrylate (HEMA) to 3-Aminopropyltriethoxysilane (APTS), were employed. By 13C NMR and mass analysis it was possible to establish the formation of coupling hybrid species. A hybrid material, with final concentration of 30% w/w of silica gel to the mass of polymer, was obtained through basic catalysed sol–gel process of tetraethoxysilane (TEOS) and the alkoxysilyl unit of the hybrid monomer, followed by in situ free-radical polymerization. Optical transparency and higher glass transition temperature than pHEMA suggest an increase in either density or strong interphase interactions. Moreover, pHEMA/SiO2 gel blend hybrid exhibits better thermal stability than the as-prepared polymer. Morphology and structure were studied through scanning electron microscopy (SEM), transmission electron spectroscopy (TEM), and dynamic light scattering (DLS). The structure of the hybrid consisted of nanosilica, 10 nm in mean diameter, uniformly dispersed in the pHEMA phase with strong interactions between the phases. Nevertheless, the swelling ratio of the hybrid was comparable to pHEMA. Using FT-IR spectroscopy, SEM and energy dispersive system (EDS), XRD analysis in vitro bioactivity of the hybrid, due to the inorganic phase, was ascertained therefore, the obtained hybrid can be used to make bioactive scaffold for bone engineering.