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Highly heterotactic polymerization of methacrylates — Higher order stereoregulation and stereochemical significance
Author(s) -
Kitayama Tatsuki,
Hirano Tomohiro,
Zhang Yajun,
Hatada Koichi
Publication year - 1996
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.19961070128
Subject(s) - methacrylate , polymerization , polymer chemistry , triad (sociology) , alkyl , anionic addition polymerization , solution polymerization , methyl methacrylate , toluene , polymer , chemistry , molar mass distribution , materials science , organic chemistry , psychology , psychoanalysis
A combination of tert ‐butyllithium ( t ‐BuLi) and bis(2,6‐di‐ t ‐butylphenoxy)methylaluminium (MeAI(ODBP) 2 ) was found to be an efficient initiator for heterotactic living polymerization of certain alkyl methacrylates in toluene at low temperatures. The polymerization of methyl methacrylate (MMA) with t ‐BuLi/MeAI(ODBP) 2 (AI/Li=5 mol/mol) in toluene at −78°C gave heterotactic‐rich poly(methyl methacrylate) (PMMA) with narrow molecular weight distributions (MWDs) (heterotactic triad fraction mr = 68%, ratio of weight‐ to number‐average molecular weights M̄w/M̄n = 1.06‐1.17). Other alkyl methacrylates also gave heterotactic polymers under the same conditions; in particular, ethyl and butyl methacrylates gave polymers with heterotactic triad fractions of 87%. The highest triad heterotacticity of 91.6% was obtained for the polymerization of ethyl methacrylate at −95°C. Some characteristic features of this stereospecific polymerization were discussed based on the polymerization results combined with other structural information of the polymer such as chain‐end stereostructure and stereosequence distribution in the main chain.