Lipase‐Catalyzed Transformation of Poly(lactic acid) into Cyclic Oligomers

Abstract

Enzymatic transformations into cyclic oligomers were carried out with the objective of developing chemical recycling of poly(lactic acid)s, such as poly(D,L-lactic acid) (PDLLA), poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA), which are typical biodegradable polymers. They were degraded by lipase in an organic solvent to produce the corresponding cyclic oligomer with a molecular weight of several hundreds. PDLLA (with a Mw of 84,000) was quantitatively transformed into cyclic oligomers by lipase RM (Lipozyme RM IM) in chloroform/hexane at 60 degrees C. PLLA (with a Mw of 120,000) was transformed into cyclic oligomer by lipase CA (Novozym 435) at a higher temperature of 100 degrees C in o-xylene. The oligomer structure was identified by 1H and 13C NMR spectroscopy and MALDI-TOF (matrix assisted laser desorption/ionization-time-of-flight) mass spectrometry.

Enzymatic Synthesis of Polyesters via Ring-Opening Polymerization

“…Poly(L-lactic acid) (PLLA) having an M w of 120 000 was transformed into cyclic oligomers by lipase CA at 100 • C. Similar results were obtained by the lipase-catalyzed degradation of poly(DL-lactic acid) (PDLLA). That is, PDLLA having an M w of 84 000 was quantitatively transformed into cyclic oligomers with the peaktop oligomerzation degree of the octamer (8-mer) by lipase RM at 60 • C. No linear-type fraction was detected in the MALDI-TOF mass spectrum [159].…”

New Insight into Biodegradation of Poly (L-Lactide), Enzyme Production and Characterization

“…The treatment process by the activity of enzyme is under mild condition, regarding as a clean process, and does not contain any undesirable byproducts such as racemic of PLA after degradation. Poly(lactic acid) such as poly(DL-lactic acid), poly(D-lactic acid) and poly(L-lactic acid) were degraded by the activity of lipase in an organic solvent to produce cyclic oligomer with several enzyme for example, lipase RM (Lipozyme RM IM) and lipase CA (Novozym 435) at 60-100C (Takahashi et al, 2004). This report suggested that the cyclic oligomer might be suitable for repolymerization and recycling of PLA.…”

Candida antarctica Lipase B as Catalyst for Cyclic Esters Synthesis, Their Polymerization and Degradation of Aliphatic Polyesters

“…So far, enzymatic polymer recycling in the presence of N-435 was conducted for: PLLA [103], PBA [104], PBS [104], PCL [105], PHB [106], poly(trimethylene carbonate) (PTMC) [107], PTCL [108], and in some cases the repolymerization step was also investigated [107].…”

“…The systematic studies of Matsumura research group [103], showed that cyclic oligomers of l-lactide with a molar mass of several hundred, can be obtained in o-xylene solvent at 100 °C with 500 wt% of N-435. Much lower temperature of degradation was applied for poly(R,S)-3-hydroxybutanoate [106] and PCL [109], which were transformed into a reactive cyclic products in toluene, to give oligomers with M n less than 500 g mol −1 .…”