Novel preparation method and the characterization of polyurethane-acrylate/ nano-SiO ₂ emulsions

Abstract Polyurethane-acrylate/SiO ₂ composite (SPUA) emulsions were synthesized by in situ polymerization accompanying the sol-gel process, in which the hydrolysis reaction and polymerization of monomers could be accomplished at the same time. The particle morphology of the SPUA emulsions was observed by scanning electron microscopy and transmission electron microscopy. The particle diameter was measured on a laser particle size analyzer. The molecular structure of the copolymers was characterized by Fourier transform infrared spectrometer (FTIR). Furthermore, tensile testing machine, Shore durometer, and thermogravimetric analyzer were used to investigate the mechanical properties, hardness, and thermal properties. The results indicated that, by increasing the mass fraction of tetraethyl orthosilicate (TEOS), the mechanical properties of the films were improved remarkably. When the weight % of TEOS was 8% in the SPUA emulsion, the water absorption of obtained film was 2.1%, the tensile strength was 16.8 MPa, the shore hardness was 94, and the temperature for the maximal thermal mass-loss rate was 416°C.