Synthesis and cationic photopolymerization of oligomers bearing terminal and internal enol ether groups

The synthesis of multifunctional oligomers containing cationically polymeri zable enol ether groups at the terminal positions and along the backbone wa s achieved through the use of simple, straightforward reaction chemistry. T his involves first, the etherification of 2-butene-1,4-diol with alpha,omeg a -dibromoalkanes or an alkyl ether linking group followed by an end cappin g reaction with allyl bromide. Thereafter, the base catalyzed isomerization of the allylic double bonds was carried out to afford the desired enol eth er oligomers. The cationic photopolymerizations of these oligomers were stu died using onium salt photoinitiators. While crosslinked polymers were obta ined in all cases, the rates of polymerization were found to be strongly de pendent on the character of the linking group.