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2531733 
Journal Article 
Living coupling reaction in living cationic polymerization .1. Coupling reaction of living polyisobutylene 
Bae, YC; Fodor, Z; Faust, R 
1997 
No 
Macromolecules
ISSN: 0024-9297
EISSN: 1520-5835 
American Chemical Society 
30 
2 
198-203 
English 
WOS:A1997WF22900006 
The living coupling reaction of living polyisobutylene (PIE), prepared by the 2,4,4-trimethyl-2-chloropentane/TiCl4/hexane:methyl chloride (60:40, v:v)/-80 degrees C system, has been studied using 1,3-bis(1-phenylethenyl)benzene (MDDPE), 2,2-bis[4-(1-phenylethenyl)phenyl]propan (BDPEP), and 2,2-bis[4-(1-tolylethenyl)phenyl]propane (BDTEP) as coupling agents. The reaction of Living PIE with MDDPE yielded the monoadduct, possibly due to delocalization of positive charge over the meta-substituted benzene ring upon monoaddition and thereby decreased reactivity of the second double bond. Using BDPEP and BDTEP which have two diphenylethylene (DPE) moieties separated by an electron-donating spacer group, rapid and quantitative coupling was achieved independently of the chain length of the original PIE. The coupled product exhibited doubled molecular weight and narrowed molecular weight distribution. Direct evidence of the quantitative coupling reaction was also obtained by comparison of the H-1 NMR spectra of the samples before and after the coupling reaction. Kinetic studies by H-1 NMR spectroscopy indicated the coupling reaction of living PIE by BDPEP is a consecutive reaction where the second addition is faster than the first one. By kinetic treatment of the experimental results, it was found that the second addition is about 5 times faster than the first one. As a result, high coupling efficiency was also observed when excess BDPEP was used.