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Living carbocationic polymerization of isobutylene by tert ‐amyl alcohol/BCl 3 /1‐methyl‐2‐pyrrolidinone initiating system
Author(s) -
Pratap G.,
Mustafa S. A.,
Hollis W. K.,
Heller J. P.
Publication year - 1992
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1992.070440616
Subject(s) - isobutylene , polymer chemistry , gel permeation chromatography , dispersity , prepolymer , chemistry , polymer , molar mass distribution , polymerization , butyl rubber , pendant group , organic chemistry , copolymer , natural rubber , polyurethane
1‐Methyl‐2‐pyrrolidinone has been investigated, for the first time, as an efficient electronpair donor in conjunction with tert ‐amyl alcohol and BCl 3 in CH 2 Cl 2 diluent at −40°C for the living polymerization of isobutylene. The use of this new m onofunctional ini tiator ‐trans fer (minifer) system has led to the synthesis of low molecular weight, living (near‐monodisperse) polyisobutylenes carrying “ethyl” head group and “ tert ‐chloro” end group (asymmetric telechelic polyisobutylenes). The nature of these groups was confirmed by 1 H‐NMR spectroscopy. The living nature of the α‐ethyl‐ω‐( tert ‐chloro)polyisobutylenes has been demonstrated by a linear plot, passing through the origin, of number‐average molecular weight ( M̄ n ) vs. the amount of polymer formed ( W p ) and a horizontal N (number of polyisobutylene molecules) vs. W p plot. These results are further substantiated by gel permeation chromatography data of these polymers, and the molecular weight distributions of these polymers are narrow (low M̄ w / M̄ n = 1.1–1.2). The initiating efficiencies ( I eff ) are close to 100% with this system. Dehydrochlorination of the prepolymer has yielded an isopropylidene ( exo ‐olefin) end group. Structure of the end group in the resulting polymer, α‐ethyl‐ω‐(isopropenyl)polyisobutylene, was confirmed by FTIR spectroscopy.