Theoretical study of chain transfer in anionic polymerization. Transfer by the mechanism of side-group substitution

✍ Scribed by Litvinenko, Galina I. ;Arest-Yakubovich, Alexander A.

• Publisher: Wiley (John Wiley & Sons)
• Year: 1992
• Weight: 451 KB
• Volume: 1
• Category: Article
• ISSN: 1018-5054
• DOI: 10.1002/mats.1992.040010506

✦ Synopsis

Abstract

A new theoretical consideration of chain transfer to monomer in the anionic polymerization of hydrocarbon monomers is presented. It is shown that the kinetic scheme used in theoretical studies reported previously contradicts the widespread views on the chemical mechanism of carbanionic reactions. It is suggested that the most probable path of the transfer reaction is the proton abstraction from the side group of the monomer; the terminal double bond of the monomer molecule remains unchanged, and therefore the intermediate species can participate in succeeding reactions as a macromonomer. The molecular characteristics of polymer formed in processes with monomer transfer by side‐group substitution are determined. At high conversion, the polymer formed in such a process is shown to possess a number‐average degree of polymerization, P̄~n~, approaching the theoretical value for living polymers, and a P̄~w~ exceeding it the more the higher the intensity of transfer. Furthermore, it shows a broad molecular weight distribution and a fairly noticeable degree of branching. These results considerably differ from those previously reported.