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The nature of the growing species in living cationic polymerization: Principles, stereochemistry, and in‐situ NMR analysis
Author(s) -
Sawamoto Mitsuo
Publication year - 1994
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19940850104
Subject(s) - cationic polymerization , carbocation , chemistry , steric effects , living cationic polymerization , nucleophile , polymerization , salt (chemistry) , living polymerization , living anionic polymerization , polymer chemistry , counterion , in situ , polymer , organic chemistry , anionic addition polymerization , radical polymerization , ion , catalysis
The objective of this paper is to discuss: (i) the general approaches to living cationic polymerizations; (ii) the nature of the growing species thus generated. For the first, it is concluded that three general methods are currently available which involve the nucleophilic stabilization of the growing carbocations by (a) a suitable counteranion, (b) an added Lewis base, or (c) an added neutral salt. According to this view, a variety of initiating systems are classified. For the second, findings are presented for the recently developed living cationic polymerization of vinyl ethers by the HCl/SnCl 4 initiating system in the presence of an added salt ( n Bu 4 N + Cl − ). The nature of the growing species therein is discussed on the basis of the steric structure of the living polymers, relative to nonliving counterparts, and the in‐situ 13 C NMR spectroscopic analysis of model reactions where the interaction of the growing end model [CH 3 CH(OR)Cl] with SnCl 4 and the added salt is analyzed.