Synthesis of isobutenyl-telechelic polyisobutylene by functionalization with isobutenyltrimethylsilane

✍ Scribed by Lars V. Nielsen; Rasmus R. Nielsen; Bo Gao; Jørgen Kops; Béla Iván

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 544 KB
• Volume: 38
• Category: Article
• ISSN: 0032-3861
• DOI: 10.1016/s0032-3861(96)00802-6

✦ Synopsis

Isobutenyl-telechelic polyisobutylenes (PIBs) were synthesized by reacting tert-chlorine-telechelic and living PIBs with isobutenyltrimethylsilane (IBTMS) in the presence of TIC14 in CH2Cl2/hexane (40/60 v/v) solvent mixtures at -78°C. In order to obtain PIB oligomers, living polymerization of isobutylene was induced by the di-(2-hydroxy-2-propyl)-5-tert-butylbenzene (tBuDiCumOH)/BCI3 combination in CHzC12 followed by addition of required amounts of hexane and TiC1 a to avoid polymer precipitation and permanent termination. Although quantitative end-quenching of living PIB was achieved with IBTMS, chain coupling between the living PIB chains and isobutenyl-ended polymers also occurred. This side reaction was avoided by isobutenylation of tert-chlorine-telechelic PIB with IBTMS in the presence of TiC1 a. The resulting isobutenyltelechelic PIB contains exclusively exo-CH2-C(CH3)=CH 2 endgroups, and is free from-CH=C(CH3)2 endo olefins usually obtained in small quantities (~3 8% of total double bonds) as a side product of other methods used in the past.