The thermal properties and the microstructures of organic-inorganic nano-composite materials

The imaging capability of the atomic force Microscope (AFM) with thermal accessory is utilized to study the nano-scale T$_{g }$and morphological evolution of silica-polyacrylate composites. The polymer matrix is made by irradiation-inducing polymerization of the blend of TEGDA and EOBDA (Ethoxylated (3) Bisphenol A Diacrylate)acrylate. The surface area ratio of the nano-particles and the measured frame is applied to define the melting event on the composite film and make a direct comparison with the macro-scale T$_{g}$ obtained from Differential Scanning Calorimetry (DSC) and Thermo-Mechanical Analyzer (TMA). The decomposition temperature T$_{d}$ of the composites is measured by Thermo-Gravimetic Analyzer (TGA). In analog to the mechanical property transition as the nanoparticle content reaches the critical density, the measured melting temperature of these hybrid materials displays a nonlinear trend as the filler content increases. When the silica particles form a percolation network within the composite, the 2-D melting and 3-D disintegration behave differently. This discrepancy arising either from the fundamental difference of physical nature or the instrumental limits will be discussed.