New Method To Reduce Oxygen Surface Inhibition by Photorelease of Boranes from Borane/Amine Complexes

A new photochemical approach for free radical polymerization has been developed. The system releases trialkylborane from its complex with 4-(dimethylamino)pyridine upon irradiation. The presence of a free borane in the formulation, when it encounters oxygen, promotes radical polymerization. The system, when irradiated by an ergonomic 395 nm LED array, is able to efficiently overcome surface oxygen inhibition. The properties of the resulting photopolymer surfaces either matched or exceeded those of controls polymerized under N2 atmosphere or with high-intensity light source. Results of experimental and computational studies probing the mechanism of borane photorelease are also discussed.