Wu Guanying

The synthesis of chlorine-terminated telechelic polyisobutylene

In synthesizing chlorine-terminated telechelic polyisobutylene (PIB) with a p-DCCCp-dichlorocumene/BCl3/CH2Cl2 system, it is found that cycloalkylation occurs parallel with propagation. The factors leading to cycloalkylation were investigated in detail, to clarify its origin, to define its effects upon the molecular parameters of the polymer produced and to find ways to suppress it. It is found that cycloalkylation drastically influences MW, MWD and functionality of the polymer produced. High temperature, high medium polarity, low monomer concentration and the order of addition of BCl3 and p-DCC are the main factors favoring cycloalkylation.

The role of complexation in living cationic polymerization with Lewis acid/ester systems

Higashimura reported living cationic polymerization by the CH3OOOEt/AlEtCl2/C6H5CH3 /IBVE system, however, the mechanism was obscure and the high mole ratio of CH3OOOEt/ AlEtCl2 (50/1) was unusual. To elucidate these facts the AAlEtCl2·CH3OOOEt complex was investigated in detail by 1H-NMR, IR and UV spectroscopies. It was found that CH3OOOEt was the true initiator, AlEtCl2 the coinitiator, and the ester bond the active bond. UV spectra show complexation competitions of AlEtCl2 with C6H5CH3, CH3OOOEt and H2O. Living polymerizations occur only when the CH3OOOEt/AlEtCl2 ratio is sufficiently high. The growing bands from 324 to 327nm correspond to living complexes and indicate constant monomer insertion and complex formation during propagation.