The styrene cationic polymerization with the CumOH/BF3 initiating system in presence of water was studied.The effects of concentrations of CumOH and water on monomer conversion

polymerization rate and molecular weight of polystyrene were also investigated.An exhaustive mechanistic study of the styrene cationic polymerization in presence of water was proposed by molecular simulation and analyzing terminal structure.It is found that cationic polymerization of styrene exhibits controlled characteristic when [H2O] 0.11 mol/L; the content of water in solvent has no significant influence on rate of polymerization reaction

the conversion of monomer and molecular weight.However

cationic polymerization cannot be processed under a high excess of water ([H2O] 0.11 mol/L).On the basis of calculation results of activation energy

CumOH/BF3 initiating reaction is easier to proceed comparing with CumOH/H2O initiating reaction

which is found to be in line with the experimental results.The initiation reaction of CumOH/BF3 proceeds via activation of CO bond of ComOH to give active spieces.The water may serve here as a reversible chain transfer agent not only providing control over the polymerization reaction

but also forming hydroxy terminal groups.