In this work, the effect of modified graphene oxide and polytetrafluoroethylene (PTFE) on the tribological and anticorrosion properties of waterborne polyurethane (WPU) was studied. The modified graphene oxide (MGO) was obtained by the surface functionalization modification of graphene oxide (GO) with isophorone diisocyanate (IPDI), and MGO/WPU composite coating and MGO-PTFE/WPU composite coating with different mass fractions of MGO were prepared. The tribological and electrochemical experiment results demonstrated that the tribological properties of the coating and the corrosion resistance of the worn coating were effectively enhanced under the synergistic effect of MGO and PTFE. Finally, a mechanism was proposed to explain the improvement in anticorrosion performance of the worn coating.

An optical polythiourethane based on m-xylylene diisocyanate (XDI) and 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol (BES) has been studied. Triethylamine was adopted as a catalyst, and the solid-state isothermal cure reaction was carried out using FTIR spectroscopy, in the temperature range of 75°C-105°C. The -NCO absorption band of XDI was used to monitor the conversion of diisocyanate into polythiourethane. The reaction rate enhanced with an increase in the content of the catalyst, and the gel time determined by swelling test was shorter for the system with higher catalyst content. Kinetic parameters were calculated from the infrared spectrum data, and the results showed that the curing reaction of polythiourethane accords with first-order kinetic characteristics. The activation parameters obtained from the evaluation of kinetic data were △H∗=97.22kJmol−1, △S∗=−6.77JK−1mol−1, and Ea=100.23kJmol−1. The observed negative entropy of activation value supported the formation of a transition state in the cure reaction.

A polythiourethane thermoset system based on a diisocyanate and a trithiol was investigated by dynamic rheological measurements. Strain sweep was performed to determine the linear elastic region of the thermosetting system. The changes of characteristic parameters including elastic modulus, viscous modulus, and complex viscosity were recorded in a heating ramp to trace the cross-linking and structural evolution during the curing process. Time sweep at constant temperatures was also performed to explore possible curing strategy at reduced temperatures. In addition, frequency sweep was conducted to confirm the temperature- and time-dependent viscoelastic properties of the thermoset system during the curing process. Both continuous heating and isothermal aging gave rise to solidification of the polythiourethane with similar critical structure, as evidenced by the critical values of relaxation exponent. A combination of isothermal aging and heating is expected to be a facile strategy for fabricating thermoset polythiourethane polymers at lower temperature or/and reduced curing time. A kinetic study was done to confirm the gelation characteristics of the polythiourethane system, and the activation energy was also calculated.

Curing of a thermoset polythiourethane system of a diisocyanate and a trithiol was studied by Fourier infrared (FTIR) spectroscopy, dynamic rheological measurements and scanning electron microscopy (SEM). The isocyanate conversion during the isothermal cure reaction from the FTIR spectroscopy results suggests that the rate of isocyanate conversion differs greatly in the temperature range of 100°C to 120°C. Time sweep at three constant temperatures was conducted to examine the isothermal curing process and determine the gel time of the polythiourethane system. The gel time can be determined by the crossover of storage modulus G′ and loss modulus G′′. The gel time is dramatically affected by the curing temperature. Frequency sweep was also performed to confirm the gel points obtained from the time sweep experiments. Scanning electron microscopy (SEM) observation indicates that polythiourethane polymers formed at different curing temperatures possess similar microstructures. Rheokinetics analysis shows the second-order kinetic characteristics of the cure reaction. The activation energy obtained based on the gel time was close to that obtained based on the rheokinetics analysis, indicative of the validness of the Kamal-Sourour model for the polythiourethane system. GRAPHICAL ABSTRACT Curing of a thermoset optical polythiourethane system of a diisocyanate and a trithiol was studied by Fourier infrared spectroscopy, dynamic rheological measurements and scanning electron microscopy. The conversion increased with prolonged time until the -NCO was consumed completely. Rheokinetics analysis shows the second-order kinetic characteristics of the cure reaction.

The surface modified hydrophilic zinc sulfide nano powder was prepared by hydrothermal method, and the corresponding zinc sulfide/polyurethane organic-inorganic composite transparent coating via in-situ polymerization. The structure of ZnS Nanoparticles and organic-inorganic composite coating were characterized by Infrared Spectroscopy, X-Ray Diffraction, Laser Particle Size Analyzer and Scanning Electron Microscopy. The optical properties were measured by Ultraviolet-Visible spectrophotometer and ellipsometry. The results show that the monodisperse hydrophilic nano zinc sulfide powder with a particle size of about 70 nm can be obtained by thioglycolic acid (TGA) modification, which has good compatibility with waterborne polyurethane. Nano zinc sulfide increased the refractive index of the coating significantly and the refractive index of the coatings could be controlled in the region of 1.46–1.71 organic-inorganic composite coating by adding ZnS. When the amount of nano ZnS added was 30%, the refractive index of the hybrid coating can reach 1.71, and the transmittance was more than 90%. The cured coatings were smooth and no agglomeration between nano ZnS particles could be found. After application on the surfaces of resin lens, the coatings presented better impact resistance, which indicated that the coating has application prospects in the field of fine processing of lens’ surfaces.