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

Summary: 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 M w of 84 000) was quantitatively transformed into cyclic oligomers by lipase RM (Lipozyme RM IM) in chloroform/hexane at 60 °C. PLLA (with a M w of 120 000) was transformed into cyclic oligomer by lipase CA (Novozym 435) at a higher temperature of 100 °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 transformations into cyclic oligomers with the objective of developing chemical recycling of poly(lactic acid)s. image Enzymatic transformations into cyclic oligomers with the objective of developing chemical recycling of poly(lactic acid)s.