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Polymerization of β‐butyrolactone initiated with Al(O i Pr) 3
Author(s) -
Kurcok Piotr,
Dubois Philippe,
Jèrôme Robert
Publication year - 1996
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/(sici)1097-0126(199612)41:4<479::aid-pi652>3.0.co;2-w
Subject(s) - polymerization , polymer chemistry , molar mass distribution , tacticity , monomer , alkoxide , chemistry , polymer , organic chemistry , catalysis
Polymerization of β‐butyrolactone has been studied in toluene with Al(O i Pr) 3 as an initiator. The ring‐opening polyaddition proceeds through a coordination–insertion mechanism at a very low rate. Well defined α‐isopropylester, ω‐hydroxy poly(β‐butyrolactone)s (PBL) are formed with a narrow molecular weight distribution at low monomer‐to‐initiator molar ratios, When this ratio is higher ( ca. 170), a competition occurs between propagation and side reactions, i.e. elimination, inter‐ and intra‐molecular transesterifications and thermal degradation, which is responsible for a loss of control of the PBL molecular charcteristics. The addition of a Lewis base (1 equivalent of nicotine/Al) to the Al‐alkoxide initiator has no significant effect on the polymerization rate, although the chain microstructure is deeply affected since predominantly syndiotactic PBL chains are formed (63% syndio‐diads) in contrast to a completely atactic polymer in the absence of nicotine.