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.
Three hyperbranched poly（siloxysilanes） were prepared from AB3-type monomers at the presence of Karstedt catalyst.The detailed synthesis procedures of AB3-type monomers by reaction between γ-methacryloyloxy propyltrimethoxysilane or vinyltrimethoxysilane with chlorosilane using anhydrous ferric chloride as the catalyst were described.This new approach can simplify the synthetic routes for hyperbranched polysiloxanes.FTIR,（）1H-NMR,(（）13C-NMR,)（）29Si-NMR,elemental analysis and SEC/MALLS were employed to identify the structure of the polymers. The analyses revealed that the reaction between alkoxysilane and chlorosilane could be feasibly catalyzed by anhydrous ferric chloride.The reaction of vinyltrimethoxysilane with chlorosilane could be carried out more easily than that of γ-methylacrylacyloxypropyltrimethoxylsilane with chlorosilane due to its steric hindrance effect.
