Synthesis and properties of networking waterborne polyurethane/silica nanocomposites by addition of poly(ester amine) dendrimer

The second-generation poly(ester amine) dendrimer was prepared by Michael addition reaction and esterification reaction at first. Then, a series of novel waterborne polyurethane (WPU)-based composites were prepared by the addition of poly(ester amine) dendrimer into the WPU. The structures and the morphology of the WPU composites were measured with Fourier transform infrared spectrometer, scanning electron microscopy, and X-ray diffraction. SEM images revealed that the nanosilica was well dispersed in the WPU matrix. The mechanical properties of the WPU composites were improved with the addition of poly (ester amine) dendrimer. The dynamic mechanical thermal analysis results showed that the WPU composites had higher glass transition temperature than that of pure WPU, especially after incorporation of poly(ester amine) dendrimer. This conclusion is in good agreement with the differential scanning calorimetry results. The thermal properties of the pure WPU and its composites were investigated by thermogravimetric analysis. The results showed that the initial decompose temperature began from about 250°C, and had a little increase when introducing poly(ester amine) dendrimer into the WPU matrix. POLYM. COMPOS., 2012. © 2013 Society of Plastics Engineers