Synthesis and characterization of UV curable hyperbranched poly(siloxysilane)

A new monomer, vinyltriallylsilane (CB₃), having functionnal groups with different hydrosilylation reactivity was designed and synthesized by allylation reaction from vinyltrichlorosilane. Then, photocrosslinkable hyperbranched poly(siloxysilane) with terminal allyl groups was prepared via hydrosilylation reaction of vinyltriallylsilane (CB₃) and dimethylbis(dimethylsiloxy)silane (A₂) monomers at the presence of Karstedt catalyst, and characterized by means of FTIR, ¹H-NMR, ²⁹Si-NMR, and SEC/RI/MALLS technology. The polymerization process of A₂ and CB₃ monomers was studied in situ by using FTIR. It was found that silicon hydride would preferentially react with vinyl groups during the reaction. This can cause to the generation of an intermediate with one Si - H and three allyl groups. By using it to conduct further self-polymerization, hyperbranched polymer can be obtained. The degree of branching of the resulting hyperbranched poly(siloxysilane) was calculated to be 0.44 by quantitative ²⁹Si-NMR spectroscopy, and the weight average molecular weight was 12.1 kg/mol with its polydispersity of 2.52. Finally, the UV curing behavior of the resulting polymer initiated with different photoinitors was also investigated.