Synthesis and properties of PMMA-ZrO2 organic-inorganic hybrid films

Abstract

In this work we report the synthesis process and properties of PMMA-ZrO2 organic-inorganic hybrid films. The hybrid films were deposited by a modified sol-gel process using zirconium propoxide (ZP) as the inorganic (zirconia) source, methyl methacrylate (MMA) as the organic source, and 3-trimetoxy-silyl-propyl-methacrylate (TMSPM) as the coupling agent between organic and inorganic phases. The films were deposited by dip coating on glass slide substrates from a hybrid precursor solution containing the three precursors with molar ratio 1: 0.25: 0.25 for ZP, TMSPM, and MMA, respectively. After deposition, the hybrid thin films were heat-treated at 100°C for 24 h. The macroscopic characteristics of the hybrid films such as high homogeneity and high optical transparence evidenced the formation of a cross-linked, interpenetrated organic-inorganic network. The deposited PMMA-ZrO2 hybrid films were homogeneous, highly transparent and very well adhered to substrates. Fourier Transform Infra-Red measurements of the hybrid films display absorption bands of chemical groups associated with both PMMA and ZrO2 phases. The amounts of organic and inorganic phases in the hybrid films were determined from thermogravimetric measurements. The surface morphology and homogeneity of the hybrid films at microscopic level were analyzed by scanning electron microscopy and atomic force microscopy images. From the analysis of optical transmission and reflection spectra, the optical constants (refraction index and extinction coefficient) of the hybrid films were determined, employing a physical model to simulate the hybrid optical layers. The refraction index of the hybrid films at 532 nm was 1.56.