The thiol-ene addition has been a popular tool for chemists and engineers for applications including dendrimer synthesis, surface and nanoparticle functionalization, (two-stage) optical materials, enhanced-performance coatings, and hydrolytically stable dental resins. However, to date a majority of the research has focused on primary thiols, even though secondary thiols were found to have additional benefits such as reduced odor and reduced likelihood of reacting spontaneously with the alkene in a pre-mixed solution. As such, the effect of the substitution of the thiol was studied by using model system: three isomers of butane thiol and three different alkenes, a vinyl ether, an allyl ether, and a vinyl siloxane. The kinetic rates were observed using FT-IR and NMR analysis was used to confirm conversion. It was concluded that increasing in substitution of the thiol results in a decreased kinetic rate. Reactions typically went to full conversion (85% or higher), regardless of substitution. Novel thiol monomers were then synthesized to observe how the substitution affects the polymerization kinetics as well as mechanical properties.

Kinetic differences between primary, secondary, and tertiary alkyl thiols in thiol-ene reactions

255th National Meeting (2018)

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