Investigation of the effect of ZnO nanoparticles on the thermomechanical and microbial properties of hyperbranched polyurethane-urea hybrid composites

Hybrid coatings of hyperbranched polyurethane-urea (HBPUU) containing ZnO nanoparticles were prepared by mixing the hyperbranched polyurethane with the nanoparticles. The films were stored at room temperature and laboratory humidity conditions for one week to yield completely cured hybrid films. The ZnO nanoparticles were found to be well dispersed in the polymer up to 3 wt%. The structure-property relationship of various HBPUU-ZnO hybrid coatings was analysed using a Fourier transform infrared peak deconvolution technique with a Gaussian curve-fitting procedure, while their viscoelastic, thermomechanical and surface morphology were studied using X-ray diffraction, dynamic mechanical thermal analysis, thermogravimetric analysis, a universal testing machine, scanning electron microscopy, atomic force microscopy and contact angle instruments. The thermal stability and mechanical properties of the hybrid composite films improved with increasing ZnO content, which was believed to be due to thermal insulation in the presence of nanoparticles. Water contact angle data suggested that the hydrophobic character of the hybrid composites increased with increasing nanoparticle concentration. The antimicrobial property of the HBPUU-ZnO hybrid coatings was studied using the disc diffusion method. HBPUU-ZnO hybrid coatings showed good antimicrobial properties compared to HBPUU.