The efficient synthesis of poly(isobutylene-b-α-methylstyrene) (PIB-b-PαMeSt) copolymer has been accomplished by living cationic polymerization using sequential monomer additions. Living PIB was first prepared by the 2-chloro-2

4

4-trimethylpentane (TMPCl)/TiCl4/DtBP/C6H12∶MeCl=50∶50V/V/-80℃ polymerization system. Subsequently

the living PIB chain end was converted to the corresponding diphenylalkyl end by capping with 1

1-di-p-tolylethylene (DTE).Ti(OiPr)4 was added to reduce the Lewis acidity

followed by the addition of α-MeSt. When Ti(OiPr)4 was introduced into the polymerization system

the complexes of Ti2C 8-x(OiPr)x were formed rapidly. By changing the stoichiometry

the Lewis acidity of TiCl4 can be moderated in a wide range. This was corroborated by our visual observation that upon addition of Ti(OiPr)4 the orange color of the diphenyl carbenium ion turned into the yellow-green color. This indicated that highly reactive species convert into less reactive species. The PIB-b-PαMeSt copolymers were characterized by 1H-NMR spectroscopy and triple detection SEC: refractive index (RI)

multi-angle laser light scattering (MALLS) and ultraviolet (UV) detector. The effects of the polymerization time for α-MeSt (t2) on conversion of monomer

dn/dc value

molecular weight and molecular weight distribution as well as the effect of Ti(OiPr)4 concentrations on the polymerization rate were investigated. The results showed that the dn/dc values of block copolymers increased with increasing poly α MeSt compositions. And molecular weight distributions of the resulting polymers stayed relatively narrow

less than 1.2 (MWD≤1.2).LS

RI and UV traces of the resulting PIB-b-PαMeSt copolymer had the same eluting time without any tailing which demonstrated the blocking efficiency is close to 100%.The kinetics of the cationic polymerization of α-MeSt in the presence of Ti(OiPr)4 were determined by the gravimetric monitoring of the polymer yield as a function of the reaction time.The monomer conversion gradually increased with increasing polymerization time

and the conversion decreased with increasing ［Ti(OiPr)4］/［TiC4］ ratio.Interestingly

there was a precipitous drop in conversion at ［Ti(OiPr)4］/［TiCl4］ ratio 1

with the 1.1 ［Ti(OiPr)4］/［TiCl4］ ratio ca. 5% conversion was obtained in 1 h.On the basis of these observations

it was concluded that Lewis acidity of TiCl4 decreased with increasing the ［Ti(OiPr)4］ to ［TiCl4］ ratio. When the ［Ti(OiPr)4］ to ［TiCl4］ ratio was more than 1.1

a slight excess of Ti(OiPr)4 deactivated TiCl4

and the active species lost.Linear plots of ln(［M］0/［M］) versus time passed through the origin demonstrated the expected first-order dependence on the monomer concentration

which proved that the concentration of growing centers remained constant.The result combined with the linear Mn-conversion plots confirmed that the polymerization was living.The kappP values obtained from the slope of the in(［M］0/［M］) versus time linear plots also showed that the rate of the polymerization decreased with increasing ［Ti(OiPr)4］/［TiCl4］ ratio.The complexes of Ti2Cl8-x(OiPr)x interacted with the growing chain end to reduce its“cationicity" and thus to decrease the polymerization rate

suppress chain transfer and termination reactions and narrow MWD.Differential scanning calorimetry (DSC) of the diblock copolymers showed two glass transitions demonstrating microphases separation.