Shih-Liang Huang

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.

Two 4,4′‐oxydiphthalic anhydride (ODPA)‐based polyimide (PI)/titania hybrid films with different morphologies were prepared through an in situ sol‐gel process. The precursor, poly(amic acid) (PAA), was synthesized using ODPA, diamine of 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane (BAPP) or 4,4′‐diaminodiphenyl ether (ODA) and a suitable amount of dimethylformamide solvent. A mixture of tetraethylorthotitanate (Ti(OEt)₄) and acetylacetone with molar ratio of 1:4 was then added to the PAA solution and mixed thoroughly. Following curing, PI/titania hybrid membranes with different crosslinkages and Ti(OEt)₄ contents were prepared. PI hybrids with the longer BAPP diamine present different morphologies and property changes related to the Ti(OEt)₄ content from those of hybrids with the shorter ODA diamine. The morphologies of the two ODPA‐based PI/titania hybrids were studied with reference to the disruption of imide ring formation. Different crosslinked structures produced were identified using Fourier transform infrared analysis from the frequency shift of the CO band and relative absorbance intensities of bands of CO group and imide ring (N). Thermal properties, O₂/N₂ gas separation performance, contact angle, storage modulus, glass transition temperature and decomposition temperature of the PI hybrids were all found to be functions of the Ti(OEt)₄ content, crosslinked structure and PI type. Copyright © 2012 Society of Chemical Industry