Preparation and characterization of segmetned- and silicone-containing polyurethanes

Abstract

The segmented polyurethanes were synthesized by the reaction of polypropylene glycols having a different molecular weight and OH-terminated dimethylsiloxane with 4,4``-diphenyl methane diisocyanate (MDI) and N-methyl diethanolamine (MDEA) as a chain extender. Diphenyl bis(4-isocyanatophenyl)silane as organosilicon diisocyanate was synthesized from corresponding diacid via Wienstock-Curtius modified rearrangement of diacidazide in benzene. This diisocyanate was reacted with N-methyl diethanolamine by the condensation polymerization to improve thermal resistance. The structures of organosilicon diisocyanate and all resulting polymers in this study were identified by IR and $^1$H-NMR spectroscopy. The obtained polyurethanes had inherent viscosity in the range of 0.25-0.36 dl/g. The thermal stability of the polyurethanes was evaluted by TGA and Tg of the polymers was determined by using DSC. It was turned out that the incorporation of silicon atom increased their thermal stabilities and that the increasing molecular weight of polypropylene glycol as a soft segment decreased glass transition temperature.