According to the mechanism of hydrosilylation

the process of“normal-sequence-dripping mode” was designed．And using such process

the monomers of dichloromethylphenethylsilane and dichloromethyl (n) hexylsilane were synthesized with high productivity(the maximal productivity of dichloromethylphenethylsilane

88％

and dichloromethyl-n-hexylsilane

96.2％) and low pollution (minute quantity of fumes in off-gas)．By Wurtz reductive coupling reaction of dichlorosilane(dichloromethylphenethylsilane and dichloromethyl(n)hexylsilane)and trichlorosilane (trichloromethylsilane and trichlorophenylsilane)

four series of two-dimensionally branched copolysilanes were designed and synthesized using the two procedures of “pre-polymerization” and “mixed-polymerization” with or without diglyme. The polymers are polymethylphenethylsilene-co-methylsilynes

polymethyl-phenethylsilene-co-phenylsilynes

polymethyl-n-hexylsilene-co-methylsilynes

and polymethyl-n-hexylsilene-co-phenylsilynes．Through the characterization of GPC

UV

1H-NMR and 29Si-NMR

the properties of such copolysilanes were determined．The effects of such factors as monomer characteristics

co-polymerization ratio (D／T)

co-polymerization mode(“pre-polymerization” and“mixed-polymerization”)

solvent additive(diglyme)and reaction time on the polymer properties

such as productivity

molecular weight and UV absorption spectra

were studied and discussed．It was discovered that the branched copolysilanes of very high molecular weight with highly bulky substituents could be obtained with “pre-polymerization”．The maximum of the molecular weight of such branched copolysilanes could reach 2.8×105

which was at least ten times as those of the branched copolysilanes derived from the mixed-polymerization procedure．The mechanism of increasing the molecular weights of branched copolysilanes was proposed