Ring-opening polymerization of ethylene brassylate in reactive extrusion and its end-of-life options

Journal article, 2025

Polyesters synthesised from renewable monomers via intensified and industrially relevant processes provide nowadays a science-to-technology breakthrough, especially if they offer a suitable end-of-life scenario for a circular economy. In this work bio-based macrolactone ethylene brassylate was polymerized by reactive extrusion and the properties of the polyester and its end-of-life options were studied. The ring-opening polymerization was tested with several catalytic systems, among which the organic base 1,5,7-triazabicyclo[4.4.0]dec-5-en (TBD) and the immobilized enzymes Lipase B from Candida antarctica and Lipase from Pseudomonas cepacia successfully synthesised poly(ethylene brassylate) (PEB). TBD served as both catalyst and initiator, yielding PEB with a molar mass of 8000 g/mol, melting temperature around 70 °C and main degradation temperature of 440 °C. Tensile tests showed that PEB had a brittle behaviour with Young's modulus of 290 MPa and elongation at break of 4 %. PEB lost 93 % of its initial weight after 90 days in compost, degrading through surface erosion. Lipase B from Candida antarctica was demonstrated successful for the enzymatic depolymerization. Therefore, enzymatic depolymerization and disintegration in compost were suggested as feasible pathways for PEB circular design.