Comparison of Effects of Different Sacrificial Hydrogen Bonds on Performance of Polyurethane/Graphene Oxide Membrane.

Processing robust mechanical properties is important for elastomeric materials. In this work, different molecular weights of polyethylene glycols (PEG) were used to modify graphene oxide (GO) in order to study the relationship between the number of hydrogen bonds and the properties of the polyurethane/graphene oxide membrane. The fact of PEG was successfully grafted onto the surface of GO was certified by Fourier transform infrared spectra, Raman spectra, X-ray photoelectron spectroscopy. The graft ratio was indicated by thermogravimetric analysis. The presence of hydrogen bonds in PUR/MGO composites membrane was proved by the cyclic loading-unloading test and stress relaxation test. The thermal stability and low-temperature resistance performance of PUR/MGO had been improved compared with PUR/GO. When the molecular weight of PEG grafted on the surface of GO was 600, the tensile strength and elongation at break of the composite membrane were optimal. The reason for the improvement of physical and mechanical properties was that the dispersion of filler in the rubber matrix and the compatibility between filler and rubber had been improved.

Synthesis of polymerizable quaternary thiazole salts and their application as antibacterial agents for dental resin.

For the purpose of endowing dental resin with antibacterial activity without impairing physicochemical properties, polymerizable quaternarized thiazole salts (QAMEMT-x) with different alkyl chain length (12, 14, and 16) were synthesized and characterized by FT-IR and 1H-NMR spectra. After adding 5 wt% of QAMEMT-x into Bis-GMA/TEGDMA (50/50, wt./wt.) dental resin, double bond conversion (DC), volumetric shrinkage (VS), flexural strength (FS) and modulus (FM), water sorption (WS) and solubility (SL), and antibacterial activity against Streptococcus mutans (S. mutans) of obtained resin systems were investigated. The results showed that 5 wt% of QAMEMT-x had no influence on DC, FS, FM, WS, and SL (α > 0.05), while could reduce VS of dental resin (α < 0.05). Cured resins with 5 wt% of QAMEMT-x all showed antibacterial activity against S. mutans, and QAMEMT-16 could endow cured resin with the strongest antibacterial activity which showed an antibacterial efficiency of more than 99%.