title: Synthesis and characterization of branched polymers from lipase-catalyzed trimethylolpropane copolymerizations.
abstract: Lipase-catalyzed terpolymerizations were performed with the monomers trimethylolpropane (B3), 1,8-octanediol (B2), and adipic acid (A2). Polymerizations were performed in bulk, at 70 degrees C, for 42 h, using immobilized lipase B from Candida antartica (Novozyme-435) as a catalyst. To determine the substitution pattern of trimethylolpropane (TMP) in copolymers, model compounds with variable degrees of acetylation were synthesized. Inverse-gated 13C NMR spectra were recorded to first determine the chemical shift positions for mono-, di-, and trisubstituted TMP units and, subsequently, to determine substitution of TMP units along chains. Variation of TMP in the monomer feed gave copolymers with degrees of branching (DB) from 20% to 67%. In one example, a hyperbranched copolyester with 53 mol % TMP adipate units was formed in 80% yield, with Mw 14 100 (relative to polystyrene standards), Mw/Mn 5.3, and DB 36%. Thermal and crystalline properties of the copolyesters were studied by thermogravimetric analysis and differential scanning calorimetry.
authors.affiliation: National Science Foundation Industry/University Cooperative Research Center for Biocatalysis and Bioprocessing of Macromolecules, Department of Chemical and Biological Sciences, Polytechnic University, Six Metrotech Center, Brooklyn, New York 11201, USA.
authors.forename: Ankur S
authors.initials: AS
authors.lastname: Kulshrestha
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
authors.forename: Hongyong
authors.initials: H
authors.lastname: Fu
authors.forename: Richard A
authors.initials: RA
authors.lastname: Gross
mesh_terms: D002152:Calorimetry, Differential Scanning; D002175:Candida; D002384:Catalysis; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D006358:Hot Temperature; D008049:Lipase / Q000737:chemistry*; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008970:Molecular Weight; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry*; D011409:Propylene Glycols / Q000737:chemistry*; D013696:Temperature; D013818:Thermogravimetry; D013997:Time Factors
chemical_list: D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D046911:Macromolecular Substances; D011108:Polymers; D011409:Propylene Glycols; C018163:trimethylolpropane; C093667:Novozyme 435; D008049:Lipase