In situ polymerization and characterization of polyester-based polyurethane/nano-silica composites

Polyester-based polyurethane/nano-silica composites were obtained via in situ polymerization and investigated by Fourier-transform infrared spectroscopy (FTIR), or FTIR coupled with attenuated total reflectance (FTIR-ATR), Transmission electron microscopy (TEM), atomic force microscopy (AFM), an Instron testing machine, dynamic mechanical analysis (DMA) and ultraviolet-visible spectrophotometry (UV-vis). FTIR analysis showed that in situ polymerization provoked some chemical reactions between polyester molecules and nano-silica particles. FTIR-ATR, TEM and AFM analyses showed that both surface and interface contained nano-silica particles. Instron testing and DMA data showed that introducing nano-silica particles into polyurethane enhanced the hardness, glass temperature and adhesion strength of polyurethane to the substrate, but also increased the resin viscosity. UV-vis spectrophotometry showed that nano-silica obtained by the fumed method did not shield UV radiation in polyurethane films. (C) 2003 Society of Chemical Industry.