Abstract: The tert-butyl acetate/TiCl₄/IB/CH₂Cl₂, Cl₂/TiCl₄/IBVE/C₆H₅CH₃, n butyl propenylate/TiCl₄/IB/ CH₂Cl₂ cationic polymerization systems were studied. Summarizing and comparing results of the GPCtraces and the characteristic absorption bands of UVand FTIRspectra respectively, one can conclude: (1) The GPCtraces of polymer changed in line with increase of initiator concentration from unimodal with comparatively high M_w to bimodal showing both high and low M_w fraction. The former unimodal traces are corresponded to single active center[TiCl₄←H₂O] and the later bimodal traces are corresponded to two active centers comprising both [TiCl₄←initiator] and [TiCl₄←H₂O]. (2) The different properties of polymers obtained by different sequences of chemicals addition and ageing procedure were due to complexation competition and equilibrium which usually required a certain period of time. (3) There are at least two sorts of initiating species in equilibrum.

Key words: Cationic polymerization, UV spectroscopy, Complexing competition