Synthesis and applications of polysiloxanes containing photocrosslinkable oxaalkylene styrenyl groups

The synthesis of photocrosslinkable polysiloxanes containing (or not) alkylfluorinated groups and oxaalkylene styrenyl groups was performed. It was carried out either by modification of commercially available polysiloxanes bearing Si-vinyl groups which were reacted with 2-mercaptoethanol followed by addition of p-(chloromethyl)styrene, or by copolycondensation of α,ω-dihydroxy polydimethylsiloxanes and dichlorosilanes bearing acetoxy groups and dichlorosilanes bearing fluorinated groups. The introduction of styrene groups was then achieved by hydrolysis of the acetoxy group into the corresponding alcohol followed by reaction with p-(chloromethyl)styrene. The structure of the final products was determined by IR, 1H and 13C NMR spectroscopies. These products have been crosslinked under UV, in the presence of a cationic photoinitiator, and showed very good release paper properties and a good thermal resistance. The properties are enhanced when the copolymers contain fluorinated groups.