title: Functionalized polycarbonate derived from tartaric acid: enzymatic ring-opening polymerization of a seven-membered cyclic carbonate.
abstract: Enantiomerically pure functional polycarbonate was synthesized from a novel seven-membered cyclic carbonate monomer derived from naturally occurring L-tartaric acid. The monomer was synthesized in three steps and screened for polymerization with four commercially available lipases from different sources at 80 degrees C, in bulk. The ring-opening polymerization (ROP) was affected by the source of the enzyme; the highest number-average molecular weight, M(n) = 15500 g/mol (PDI = 1.7; [alpha]D(20) = +77.8, T(m) = 58.8 degrees C) optically active polycarbonate was obtained with lipase Novozyme-435. The relationship between monomer conversion, reaction time, molecular weight, and molecular weight distribution were investigated for Novozyme-435 catalyzed ROP. Deprotection of the ketal groups was achieved with minimal polymer chain cleavage (M(n) = 10000 g/mol, PDI = 2.0) and resulted in optically pure polycarbonate ([alpha]D(20) = +56) bearing hydroxy functional groups. Deprotected poly(ITC) shows T(m) of 60.2 degrees C and DeltaH(f) = 69.56 J/g and similar to that of the poly(ITC), a glass transition temperature was not found. The availability of the pendant hydroxyl group is expected to enhance the biodegradability of the polymer and serves in a variety of potential biomedical applications such as polymeric drug delivery systems.
authors.affiliation: Department of Chemistry, University of South Florida, 4202 East Fowler Avenue, Tampa, Florida 33620, USA.
authors.forename: Ruizhi
authors.initials: R
authors.lastname: Wu
authors.forename: Talal F
authors.initials: TF
authors.lastname: Al-Azemi
authors.forename: Kirpal S
authors.initials: KS
authors.lastname: Bisht
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry; D002384:Catalysis; D002621:Chemistry / Q000379:methods; D016503:Drug Delivery Systems; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D007700:Kinetics; D008049:Lipase / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008970:Molecular Weight; D011076:Polycarboxylate Cement / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013644:Tartrates / Q000737:chemistry*; D013696:Temperature
chemical_list: D001672:Biocompatible Materials; D002254:Carbonates; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D011076:Polycarboxylate Cement; D011108:Polymers; D013644:Tartrates; C005506:polycarbonate; C093667:Novozyme 435; D008049:Lipase; C029768:tartaric acid