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Ring‐Opening Polymerization of Racemic β‐Butyrolactone Promoted by Salan‐ and Salen‐Type Yttrium Amido Complexes
Author(s) -
Pappalardo Daniela,
Bruno Massimo,
Lamberti Marina,
Pellecchia Claudio
Publication year - 2013
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201200737
Subject(s) - polymer chemistry , chemistry , polymerization , tacticity , steric effects , yttrium , diamine , polymer , stereochemistry , organic chemistry , oxide
A series of yttrium amido complexes bearing quadridentate binaphthyl‐bridged Schiff‐base salen‐like and diamine bisphenolate salan‐like ligands are synthesized and characterized. The complexes act as active initiators in the polymerization of rac ‐β‐butyrolactone ( rac ‐BBL) under mild conditions. The obtained poly(3‐hydroxybutyrate) (PHBs) are syndiotactic enriched. 13 C NMR spectroscopy microstructure analysis shows the probability of racemic linkages P r to be up to 0.81. Statistical Bernoullian analysis evidences that a chain‐end mechanism of steric control operates for the salan‐like compound bearing cumyl substituents in the ortho position of the phenolate rings. The melting temperatures of the syndiotactic enriched PHBs are in the range 120–157 °C, depending on the degree of stereoregularity of the polymers.