In order to enhance the reactivity of the silyl-containing ceramic precursor,a hyperbranched silyl-containing polymer with low viscosity and plenty of terminal vinyl-groups was prepared.A novel AB4 type monomer,bis（N,N-diallylamino）methylsilane,was synthesized first by aminolysis of MeHSiCl2 and then was polymerized via hydrosilylation reaction using H2PtCl6 as the catalyst.The polymerization process was monitored by FT-IR spectroscopy.The polymer product was purified via precipitation using ethyl ether and acetonitrile and was analysed by using（）1H-NMR、（）29Si-NMR and FT-IR spectroscopy.The results indicated that the polymer was hyperbranched polycarbosilazane,and α-hydrosilylation was the main reaction.The degree of branching（DB） of the hyperbranched polymer was 0.56 calculated from the（）29Si-NMR spectrum,and the average molecular weight（Mw）was 13 580 g/mol determined by light scattering method.It was found that there still existed a lot of functional vinyl end groups,which can be used as promising reaction centers for curing or modification of the polycarbosilazane.
