Silicone- and ester-containing polyurethanes with improved thermal stability

Abstract New category of aromatic polyurethanes with improved thermal stability was prepared. For this purpose, a diol with preformed silicon and ester units was synthesized through reaction of diphenylsilanediol with terephthaloyl chloride in 2:1 mol ratio. After characterization, the diol was reacted with methylene diphenyl diisocyanate and also toluene diisocyanate to prepare related polyurethanes. The polymers were characterized and their properties including molecular weight, viscosity, solubility, crystallinity, thermal behavior and stability, and flame retardancy were investigated and compared. The presence of silicon and ester units, as well as phenylation of backbone led to preparation of new aromatic polyurethanes with improved thermal stability and flame retardancy. The glass transition temperatures of polyurethanes were 132 and 153 °C, and 10 % weight losses were about 265 and 292 °C. Methylene diphenyl diisocyanate-based polymer revealed higher thermal stability and flame retardancy, but lower solubility in comparison to toluene diisocyanate-based polyurethane. Enhancing thermal stability and flame retardancy of polyurethanes is a pathway for extending their applications in modern industries.