Lipase-Catalyzed Transformation of Poly(butylene adipate) and Poly(butylene succinate) into Repolymerizable Cyclic Oligomers

Abstract

The enzymatic degradation and repolymerization were carried out with the objectives of developing the chemical recycling of aliphatic polyester-type plastics, such as the poly(butylene adipate) (PBA), poly(butylene succinate), and poly(butylene adipate-co-succinate) copolymers which are typical biodegradable plastics. They were degraded by lipase in an organic solvent solution containing a small amount of water to produce cyclic oligomers mainly consisting of the cyclic diester. The produced cyclic oligomer was readily repolymerized by lipase to produce a polyester having an equal or higher molecular weight compared to the parent polymer. As an example, PBA having an Mw of 22,000 was almost quantitatively transformed by lipase CA (Novozym 435) in water-containing toluene at 50 degrees C into the corresponding cyclic oligomers mainly consisting of dimers. Thus, the obtained oligomers were readily polymerized by lipase CA to produce the PBA with an Mw of 52,000.

Enzymatic Synthesis of Polyesters via Ring-Opening Polymerization

“…This is ascribed to the polymerizability difference between the ring-opening polymerization of the cyclic BA oligomer and polycondensation of the diol with a diacid. Similar results were obtained for poly(butylene succinate) and their copolymers [77].…”

“…Also, cyclic butylene adipate oligomers mainly consisting of a dimer showed excellent polymerizability by lipase CA to produce a high- molecular-weight polyester with an M w of 52 000. Under the same conditions, the polycondensation of diethyl adipate and 1,4-butanediol produced a lowermolecular-weight polyester [77]. A larger-membered cyclic ester-urethane oligomer was also readily polymerized by lipase CA to produce a highermolecular-weight poly(ester-urethane) with the highest molecular weight of 103 000 [78].…”

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].…”

Lipase‐Catalyzed Ring‐Opening Polymerization of Molecularly Pure Cyclic Oligomers for Use in Synthesis and Chemical Recycling of Aliphatic Polyesters

“…Lipase-catalyzed degradation of polyesters in dilute organic solvent produces repolymerizable cyclic oligomers irrespective of the type of polyester used. Substrates include PBS, [2] PBA, [2] poly(e-caprolactone) (PCL), [3,4] and poly(3-hydroxyalkanoate). [5] In a concentrated solution or in bulk, the cyclic oligomer is readily polymerized by ring-opening polymerization (ROP) with the same lipase.…”

“…[6] Thus, it is thought that cyclic oligomers are an effective intermediate for the synthesis and chemical recycling of polyesters. However, the polymerizability of cyclic oligomers with respect to their size (degree of oligomerization) [2] has not been extensively studied.…”