Structure and morphology of poly(β-hydroxybutyrate) synthesized by ring-opening polymerization of racemic (R,S)-β-butyrolactone with distannoxane derivatives

• Published in: Polymer international Vol. 49; no. 11; pp. 1348 - 1355
• Main Authors: Arcana, M, Giani-Beaune, O, Schué, F, Amass, W, Amass, A
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.11.2000; Wiley
• Subjects: Applied sciences; distannoxane catalysts; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; polyhydroxybutyrate; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; ring-opening polymerization; Ring opening polymerization; Conversion rate; Stereospecific polymer; Butyrate(hydroxy)polymer; Lactone; Complex catalyst polymerization; Experimental study; Molecular weight; Racemic; Tin complex; Reaction time; Stereospecific polymerization; Catalyst activity
• ISSN: 0959-8103; 1097-0126
• DOI: 10.1002/1097-0126(200011)49:11<1348::AID-PI491>3.0.CO;2-H

Predominantly syndiotactic poly((R,S)‐β‐hydroxybutyrate) (PHB) was synthesized by ring‐opening polymerization of racemic β‐butyrolactone with distannoxane derivatives as catalysts. We have studied the polymerization of (R,S)‐β‐BL using distannoxane derivatives as catalysts and the effects of polymerization time on crude yield and molecular weight of the polymers obtained. Then, a more detailed study of the characterization of polymers obtained using hydroxy‐ and ethoxy‐distannoxanes was performed. 13C NMR spectroscopy resolved stereosequences in synthetic PHB at the diad level for the carbonyl carbon and at the triad level for the methylene carbon. These analyses show that distannoxane catalysts produce preferentially syndiotactic polyesters (syndiotactic diads fraction from 0.56 to 0.61). Triad stereosequence distribution of PHB samples agrees favourably with the Bernoullian statistical model of chain‐end control, where ideally Φ = 4(mm) (rr)/(mr + rm)2 = 1 for perfect chain‐end control. Polymer samples synthesized from distannoxane catalysts are composed of two distinct transition endotherm components with peak temperatures of approximately 42 °C and 75 °C. The formation of two melting endotherms may be due to the presence of two different crystalline structures. © 2000 Society of Chemical Industry