Dithiol

Abstract: We used real-time Fourier transform infrared to monitor the conversion of both thiol and ene (vinyl) functional groups independently during photoinduced thiol–ene photopolymerizations. From these results, the stoichiometry of various thiol–ene and thiol–acrylate polymerizations was determined. For thiol–ene polymerizations, the conversion of ene functional groups was up to 15% greater than the conversion of thiol functional groups. For stoichiometric thiol–acrylate polymerizations, the conversion of the acrylate functional groups was roughly twice that of the thiol functional groups. With kinetic expressions for thiol–acrylate polymerizations, the acrylate propagation kinetic constant was found to be 1.5 times greater than the rate constant for hydrogen abstraction from the thiol. Conversions of thiol–acrylate systems of various initial stoichiometries were successfully predicted with this ratio of propagation and chain-transfer kinetic constants. Thiol–acrylate systems with different initial stoichiometries exhibited diverse network properties. Thiol–ene systems were initiated with benzophenone and 2,2-dimethoxy-2-phenylacetophenone as initiators and were also polymerized without a photoinitiator. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3311–3319, 2001

Abstract: Compositions comprising elastomeric polyurethane prepolymers comprising the reaction product of at least one diisocyanate selected from the group consisting of p-phenylene diisocyanate, m-phenylene diisocyanate, 1,4-cyclohexyl diisocyanate, tetramethylxylyl diisocyanate and dimethylphenyl diisocyanate and at least one polyol or polythiol characterized by the presence of two hydroxyl or thiol groups or one hydroxy and one thiol group; a monomeric diol or dithiol curing agent and vein forcing fiber are especially useful for preparing fiber-reinforced composite structures, especially for dynamic applications.