Composition, thermal and tensile properties of polyurethane-urea-silica hybrids

Abstract

Polyurethane-Urea-Silica (PUUS) hybrid solutions were synthesized by a two-stage process, based on the use of polyoxypropylene glycol (PPG), 4,4′-dicyclohexyl methane diisocyanate (H₁₂MDI), 1,4-butane diol, 3-aminopropyl-trimethoxysilane (APrTMOS) and a suitable amount of solvent. Following knife-coating and curing reaction, polyurethane/urea/silica hybrid films were prepared with different crosslinkages and silica contents through the in situ sol–gel process. The intermolecular bonding of hydrogen bonding between N–H, CO groups of PU and area and Si–O–Si crosslinked structure of APrTMOS was determined via FTIR analysis, and was correlated with thermal/tensile properties. FTIR and ESCA results indicate that the carbonyl, N–H and Si–O groups distribution contained in PU and hybrid films characterized as CO group absorption peak area ratio, N/C and Si/C atomic ratio were changed from the film's surface to the bulk with APrTMOS content. Intermolecular bonding, composition, thermal property and tensile strength of films were functions of the APrTMOS contents and PPG's molecular weight. All hybrid films exhibit a more significant change in glass transition temperature (T_g), decomposition temperatures (T_d), coefficients of thermal expansion (CTEs) and stress-strain properties than that with pure PUs. The correlation between intermolecular bonding, composition, thermal and tensile properties were investigated.