Properties of polythiourethanes prepared by thiol–isocyanate click reaction

Polythiourethane networks with systematic compositional variations of thiol [ethoxylated trimethylol-propane tri(3-mercapto-propionate), ETTMP1300 and pentaerythritol tetra(3-mercapto-propionate), PETMP] and isophorone diisocyanate (IPDI), i.e., IPDI/ETTMP1300/PETMP = 100/100/0, 100/80/20, 100/60/40, 100/40/60, 100/20/80, and 100/0/100, were prepared by base catalyzed thiol–isocyanate click type reaction where the base catalyst (tributylamine, TBA) was photolytically generated using photolatent amine (TBA·tetraphenylborate salt, TBA·HBPh₄). The kinetics of the polythiourethane network formation investigated using real-time infrared indicates that the thiol–isocyanate coupling reaction was successfully triggered photolytically and the conversion of both thiol and isocyanate reached near 100% in a matter of minutes. The T_g of the polythiourethane networks progressively increases (–8 to 143 °C by DMTA) as a function of the PETMP content due to the higher extent of crosslinks, also resulting in enhanced rubbery modulus. Very narrow full width at half maximum (15–28 °C) of tan δ peak was obtained for all six sets of polythiourethane networks, which is induced by the highly uniform and dense structures of thiol-based polymeric network. Energy damping performance of polythiourethane networks measured by nondestructive impact testing exhibited remarkably high (∼95%) and the relationship with temperature was in accordance with tan δ peak. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46070.