Fluorinated hydroxytelechelic polybutadiene as additive in cationic photopolymerization of an epoxy resin

Fluorinated hydroxytelechelic polybutadiene (PBF), which is synthesized from the radical addition of a fluorinated mercaptan onto a hydroxytelechelic polybutadiene was used as an efficient surface and mechanical modifier in original formulations to enable the UV cationic polymerization of a telechelic diepoxy cycloaliphatic oligomer, leading to crosslinked polymers. Various amounts of PBF were used (ranging between 0 and 15 wt %). The kinetics of photocrosslinking revealed that the die- poxyde conversion reached 70% only in the absence of PBF, whereas it was about 90% in the presence of 10 wt % of PBF. When the PBF content increased, the dynamic mechanical measurements showed that: (i) the glass transition temperature values decreased and (ii) the resilience increased. The hydrophobicity of these polymers was investigated from the water contact angle (WCA) values showing a surface modification of the epoxy-based system. Indeed, great modifications were noted on the extreme surface (i.e., air side) of the polymers (with WCA values as high as 120°) in contrast to those observed on the substrate side.