One‐step synthesis of polycarbonates bearing pendant carboxyl groups by lipase‐catalyzed ring‐opening polymerization

Abstract

The ring‐opening polymerization of a monomer containing a free carboxylic acid group is reported for the first time. The monomer, 5‐methyl‐5‐carboxyl‐1,3‐dioxan‐2‐one (MCC), was copolymerized with trimethylene carbonate (TMC) in an enzymatic ring‐opening polymerization conducted in bulk at 80 °C. The low‐melting TMC comonomer also solubilized the high‐melting MCC monomer, allowing for solvent‐free polymerizations. Six commercially available lipases were screened, and Candida antarctica lipase‐B (Novozym‐435) and Pseudomonas cepacia lipase were selected to catalyze the copolymerization because of their higher monomer conversions. Higher molecular weight polymers (weight‐average molecular weight = 7800–9200) were prepared when Novozym‐435 was used, with less MCC incorporated into the copolymer than used in the monomer feed. However, Pseudomonas cepacia lipase showed good agreement between the molar feed ratios and the molar composition, but the molecular weights (weight‐average molecular weight = 3600–4800) were lower than those obtained when Novozym‐435 was used. 13C NMR spectral data were used for microstructural analysis, which suggested the formation of random, linear, and pendant carboxylic acid groups containing polycarbonates with hydroxyl groups at both chain ends. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1267–1274, 2002

Acidity‐Promoted Cellular Uptake and Drug Release Mediated by Amine‐Functionalized Block Polycarbonates Prepared via One‐Shot Ring‐Opening Copolymerization

“…The polymerization could be achieved under the catalysis of novozym‐435 lipase, whereas the attempt by Sn(Oct) 2 catalysis failed owing to amine presence. Enzyme‐catalyzed polymerization has thus proven advantageous as opposed to conventional chemical preparative routines in terms of the tolerance to active groups . Our continuous effort to develop new biodegradable polymers prompted us to recently explore the enzymatic copolymerization of (ADMC) 2 and ϵ‐caprolactone (ϵ‐CL) in one‐shot feeding, which eventually yielded the random copolymers rather than the block copolymers …”

“…Enzyme-catalyzed polymerization has thus proven advantageous as opposed to conventional chemical preparative routines in terms of the tolerance to active groups. [28,36] Our continuous effort to develop new biodegradable polymers prompted us to recently explore the enzymatic copolymerization of (ADMC) 2 and e-caprolactone (e-CL) in one-shot feeding, which eventually yielded the random copolymers rather than the block copolymers. [37] Biodegradable polyesters and polycarbonates are currently in a leading position to act as the hydrophobic building block of the amphiphilic block copolymers used for biomedical application.…”

Synthesis, characterization and ring-opening polymerization of a novel six-membered cyclic carbonate bearing pendent allyl ether group

“…Recently, research on enzymatic polymerization has received increasing attention as a new environmental friendly method of polymer synthesis, in contrast to chemical methods, which generally need harsh conditions and metallic catalysts that must be completely removed especially for medical applications. Up to now, various kinds of biodegradable polymers have been synthesized by enzymatic ring-opening polymerization, such as polyesters [14] and polycarbonates [7,15]. In our previous studies, we have reported that immobilized porcine pancreas lipase on silica particles (IPPL) can effectively catalyze the ring-opening (co)-polymerization of different six-membered cyclic carbonates [16,17].…”

“…Moreover, the pendent functional groups can facilitate covalent pro-drug attachment as well as other modifications. Recently, many polycarbonates with functional groups have been synthesized, such as carboxyl [7], hydroxyl [8], amino [9], vinyl [10,11], benzyl [12], etc. The synthesis of novel cyclic monomers containing a variety of functionalities has become an important method for the development of new biodegradable polymer materials with special properties for different applications.…”

Novel Biodegradable Aliphatic Polycarbonate Based on Ketal Protected Dihydroxyacetone

“…The pendant functional groups also provide active sites for further modification such as cross-linking, grafting, attaching bioactive substances to modulate cellular responses in tissue engineering, and covalently incorporating prodrug for drug delivery. The functional groups investigated include alkyl, [2] OH, [2,3] NH 2 , [4] COOH, [5] COOR [6] and sugar groups. [7] For example, it was reported that the presence of sugar groups markedly improves hydrophilicity, mechanical properties and biodegradability of polycarbonates.…”