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Preparation, properties and biodegradation of stereoregular copolymers of ( R , S )‐3‐butyrolactone and 4‐butyrolactone
Author(s) -
Wu Bin,
Lenz Robert W.,
Scherer Thomas M.
Publication year - 1998
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/(sici)1521-3935(19981001)199:10<2079::aid-macp2079>3.0.co;2-o
Subject(s) - copolymer , differential scanning calorimetry , biodegradation , gel permeation chromatography , polymer chemistry , substrate (aquarium) , glass transition , chemistry , tacticity , carbon 13 nmr , proton nmr , polymer , organic chemistry , polymerization , physics , thermodynamics , geology , oceanography
Copolymers obtained from the copolymerization of ( R,S )‐3‐butyrolactone (( R,S )‐3‐BL) and 4‐butyrolactone (4‐BL) catalyzed by isobutylaluminoxane were compared in structure and properties to copolymers having the same types of repeating units produced by Alcaligenes eutrophus when grown with an appropriate substrate or substrate or substrate mixtures. Copolymers with 4‐BL contents up to 33 mol‐% were prepared and characterized by 1 H NMR, 13 C NMR, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The copolymers had a sequence distribution of 3‐hydroxybutyrate (3‐HB) and 4‐hydroxybutyrate (4‐HB) units which were non‐random in that very few, if any, sequences of more than two successive 4‐HB units were present. The 3‐HB units are believed to be separated into isotactic ( R ) and ( S ) blocks, but thermal analysis by DSC showed that both the glass transition temperatures and melting temperatures decreased in a regular manner with increasing contents of 4‐HB units. Number average molecular weights of the copolymers ( M n ) ranged from 7000 to 15000. Biodegradation tests with a bacterial hydrolase showed that the biodegradation rates increased with increasing contents of 4‐HB units, as is the case for the equivalent bacterial copolymers.