To achieve (meth)acrylate UV-curing and thiol-ene photopolymerization combined in binary systems

vinyl monomers with high reactivity (meth)acryl carbon carbon double bonds and low radical reactivity (meth)allyl carbon carbon double bonds

specifically

methallyl acrylate

allyl acrylate and methallyl methacrylate

have been synthesized by an optimized carboxylate method.The photopolymerizations between trimethylolpropane tris(3-mercaptopropionate) (TMMP) and vinyl monomers

using 1173 as photoinitiator

are investigated by real-time FTIR to understand the effects of chemical structure of alkene

light intensity and amount of initiator on the photopolymerization behavior of thiol-vinyl binary systems

in which vinyl monomers contain two kinds of carbon carbon double bonds.It is discovered that

in all of these binary systems

(meth)-acryl carbon carbon double bond reactivity is the highest

followed by (meth)allyl carbon carbon double bond reactivity

while thiol group reactivity is the lowest.Methyl substituents on different carbon carbon double bonds of vinyl monomers have different effects on the thiol-vinyl photopolymerization.Methyl substituents on allyl carbon carbon double bonds have much greater influence on behavior of thiol-vinyl photopolymerization than the methyl substituents on acryl carbon carbon double bonds.The conversion of thiol decreases with increasing methyl substituent.In methallyl acrylate photopolymerization system

two types of carbon carbon double bonds (acryl and methallyl) present almost equal reactivity and achieve high conversion.