Synthesis and characterizations of waterborne polyurethane–silica hybrids using sol–gel process

Using a sol–gel process nanometer-scale silicas were incorporated into waterborne polyurethanes (PUs) which were synthesized from isophoronediisocyanate (IPDI), poly(tetramethyleneglycol) (PTMG), dimethylolpropionic acid (DMPA), triethylamine (TEA), diethylenetriamine (DETA) and 3-aminopropyltriethoxysilane as coupling agent. Thermal, mechanical, and dynamic mechanical properties of the hybrid composite have been studied. 29Si-NMR spectra gave evidence of condensation reaction between silica and silanes encaping the PU prepolymers, whereas transmission electron microscopy (TEM) showed the high connectivity of hybrid composites. It was found that greater thermal and mechanical properties of waterborne PU/silica hybrid composite were obtained when chemical networks were formed between PU and silica.