Production of biodegradable polyesters via enzymatic polymerization and solid state finishing

Abstract

The synthesis of aliphatic polyesters (PEs) derived from diols (1,4-butanediol and 1,8-octanediol) and diacids or their derivatives (diethyl succinate, sebacic acid, 1,12-dodecanedioic acid, and 1,14-tetradecanedioic acid) was achieved in order to produce poly(butylene succinate) (PE 4.4), poly(octylene sebacate) (PE 8.10), poly(octylene dodecanate) (PE 8.12), and poly(octylene tetradecanate) (PE 8.14). The herein suggested procedure involved two stages, both sustainable and in accordance with the principles of "green" polymerization. The first comprised an enzymatic prepolymerization under vacuum, in the presence of diphenylether as solvent using Candida antarctica lipase B as biocatalyst, whereas a low-temperature postpolymerization step [solid state polymerization (SSP)] followed in order to upgrade the PEs quality. In the enzymatically synthesized prepolymers, the range of number-average molecular weight attained was from 3700 to 8000 g/mol with yields reaching even 97%. Subsequently, SSP of PE 4.4 and 8.12 took place under vacuum or flowing nitrogen and lasted 10-48 h, at temperatures close to the prepolymer melting point (T m 2 T SSP varied between 4 C and 14 C). The solid state finishing led to increase in the molecular weight depending on the prepolymer type, and it also contributed to improvement of the physical characteristics and the thermal properties of the enzymatically synthesized PEs.

Environmentally benign synthesis of saturated and unsaturated aliphatic polyesters via enzymatic polymerization of biobased monomers derived from renewable resources

“…Similar results were reported by Catalani el al. 24 and Papaspyrides et al 50 on the effect of the chain length of dicarboxylic acids/diacid ethyl esters on enzymatic polymerization. Catalani el al.…”

Enzymatic Synthesis of Polyesters and Their Bioapplications: Recent Advances and Perspectives

“…However, higher concentration of enzyme not always results in higher molecular weight as demonstrated by Kanelli et al. [ 93 ] They studied the effect of 10 and 20 wt% of immobilized CALB over the polymerization reaction of 1,8‐octanediol and 1,12‐dodecanedioic acid. Although an improvement in the reaction yield was observed with higher amount of enzyme as catalyst, both reactions produced polymers with M n differing only by about 500 g mol −1 ; M n reached a plateau for the reaction conditions studied despite of the enzyme concentration.…”

“…In addition, Kanelli et al. [ 93 ] observed an increasing trend in the M n after the enzymatic polymerization for 4 h of 1,8‐octanediol with dicarboxylic acids of C4 and C10 lengths in diphenyl ether. In this particular case, a further increase of the diacid length from C10 to C14 decreased the M n from 8020 to 5360 g mol −1 .…”

Enzymatic synthesis of biobased aliphatic–aromatic oligoesters using 5,5′-bis(hydroxymethyl)furoin as a building block

“…21 On the other hand, recent studies suggested a benecial effect of an increase of the diester length on the results of enzymatic polycondensation. 12,32,33 For these reasons we moved to verify the extendibility of the approach to longer diacid esters. The sebacic acid diethyl ester was chosen as the model substrate and its transesterication with DHMF was rst proven at atmospheric pressure in dry THF, as described for diethyl succinate.…”