Search

EP-4741451-A1 - METHOD FOR DEGRADING A VINYL POLYMER

EP4741451A1EP 4741451 A1EP4741451 A1EP 4741451A1EP-4741451-A1

Abstract

A method for degrading a vinyl polymer having an initial molar mass in order to form at least one degradation product having a final molar mass lower than the initial molar mass comprises a) providing a water-based emulsion of the vinyl polymer; b) mixing the water-based emulsion with at least one enzyme-mediator system to obtain a reaction mixture, said at least one enzyme-mediator system comprising at least one multi-copper oxidase chosen among a laccase, a laccase-ferroxidase, a laccase-like multi-copper oxidase or a mixture thereof, and at least one respective mediator, said at least one multi-copper oxidase and said at least one respective mediator being mixed sequentially with the water-based emulsion or provided as a pre-mix preserved under anaerobic conditions, until being mixed with the water-based emulsion; c) stirring the reaction mixture under an atmosphere comprising dioxygen; and d) recovering the at least one degradation product of the vinyl polymer.

Inventors

  • BISSARO, Bastien
  • TATON, DANIEL
  • PUJOL, Manon
  • ALMEIDA GONSALES, Stella

Assignees

  • Centre National de la Recherche Scientifique
  • Institut National de la Recherche pour l'Agriculture, l'Alimentation et l'Environnement
  • UNIVERSITE DE BORDEAUX
  • Institut Polytechnique de Bordeaux
  • Université d'Aix Marseille

Dates

Publication Date
20260513
Application Date
20241112

Claims (15)

  1. A method for degrading a vinyl polymer having an initial molar mass in order to form at least one degradation product having a final molar mass lower than the initial molar mass, the method comprising : a) providing a water-based emulsion of the vinyl polymer; b) mixing the water-based emulsion with at least one enzyme-mediator system to obtain a reaction mixture, said at least one enzyme-mediator system comprising: - at least one multi-copper oxidase chosen among a laccase, a laccase-ferroxidase, a laccase-like multi-copper oxidase or a mixture thereof, and - at least one respective mediator, said at least one multi-copper oxidase and said at least one respective mediator being: - mixed sequentially with the water-based emulsion, or - provided as a pre-mix preserved under anaerobic conditions, until being mixed with the water-based emulsion; c) stirring the reaction mixture under an atmosphere comprising dioxygen; and d) recovering the at least one degradation product of the vinyl polymer.
  2. The method according to claim 1, in which the vinyl polymer is obtained by polymerization or copolymerization of vinylic monomers of formulae wherein R is independently selected from H, CH 3 or CF 3 , R' is independently selected from: - an atom chosen among H, F, Cl, Br, or I, - a linear or branched alkyl from 1 to 10 carbon optionally substituted by one or more -COOH group, - a group -COOH, - a group -COOR" wherein R" is a linear or branched C 1 -C 10 alkyl group optionally substituted by a group OH, - an optionally substituted benzyl group or a substituted phenyl group where said substituents are selected from H, F, Cl, Br, I or a C 1 -C 6 linear or a branched alkyl, - O-C 1 -C 6 alkyl group or a group-COH, or a group -COOH, or a group -COOR", - a group -NH 2 , or a group -O-COOR" or a group -CN, or a group -B (OH) 2 , - a C 1 -C 6 heteroaryl group wherein said heteroaryl group comprises one, two or three N atoms or a S atom, - a group -CO-NH2, -CO-NHR, -CO-N(R) 2 , - a dimethoxysilane or trimethoxysilane group.
  3. The method according to claim 1 or 2, in which the vinyl polymer is chosen among polyethylene, polypropylene, polystyrene, poly(vinyl chloride), poly(alyl) methacrylate, poly(alkyl methacrylate) .
  4. The method according to any one of claims 1 to 3, in which the vinyl polymer has an initial degree of polymerization (DP) of at least 10, preferably at least 100, more preferably at least 500, notably at least 1,000, notably at least 10,000, notably at least 100,000.
  5. The method according to any one of claims 1 to 4, further comprising, before step a), a step 1) comprising: - providing the vinyl polymer and - forming the water-based emulsion of the vinyl polymer by mixing the vinyl polymer with an interfacial agent.
  6. The method according to any one of claims 1 to 5, in which the vinyl polymer has an initial concentration in the reaction mixture comprised from 0.5 to 200.0 g/L, for example from 5.0 to 100.0 g/L, from 5.0 to 80.0 g/L, from 10.0 to 70. g/L, from 20.0 to 60.0 g/L or from 30.0 to 40.0 g/L, or from 5 to 15 g/L.
  7. The method according to any one of claims 1 to 6, in which the at least one multi-copper oxidase is a multi-copper oxidase which is extracted from a microorganism chosen among fungal species belonging to the Trametes genera.
  8. The method according to any one of claims 1 to 7, in which the at least one multi-copper oxidase has an initial concentration in the reaction mixture comprised from 0.1 to 40.0 enzyme units per mL of reaction mixture (U/mL), preferably from 0.5 to 30 U/mL, more preferably from 1.0 to 20.0 U/mL, more still more preferably from 1.0 to 10.0 U/mL, notably equal to 2.0 U/mL.
  9. The method according to any one of claims 1 to 8, in which the at least one multi-copper oxidase is a high-redox potential enzyme having a standard redox potential of at least 0.600 V versus normal hydrogen electrode (NHE), preferably at least 0.700 V, even more preferably at least 0.750 V.
  10. The method according to any one of claims 1 to 9, in which the mediator is chosen from the group consisting of 1-hydroxybenzotriazole (HBT) and its derivatives, N-hydroxyacetanilide (NHA), N-acetyl-N-phenylhydroxylamine (NEIAA), 3- hydroxy 1,2,3-benzotriazin-4(3H)-one (HBTO), N-hydroxyphtalimide, (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), violuric acid, promazine and phenolic compounds such as vanilline and acetovanillone or a mixture thereof.
  11. The method according to any one of claims 1 to 10, in which the mediator has an initial concentration in the reaction mixture comprised from 1.0 to 100.0 millimole per liter (mmol/L), preferably comprised from 1.0 to 50.0 mmol/L, more preferably from 1.0 to 30.0 mmol/L, notably from 3.0 to 25.0 mmol/L.
  12. The method according to any one of claims 1 to 11, in which the reaction mixture has a pH comprised from 3.5 to 7.0, more preferably from 4.0 to 7.0, more preferably from 5.0 to 7.0 and even more preferably from 6.0 to 7.0.
  13. The method according to any one of claims 1 to 12, further comprising: adding at least one additional vinylic monomer to the reaction mixture.
  14. The method according to claim 13, in which said at least one additional vinylic monomer has an initial concentration in the reaction mixture comprised from 2 to 300 millimolar, from 2 to 200 millimolar, from 2 to 100 millimolar, from 2 to 50 millimolar, from 2 to 25 millimolar, from 2 to 10 millimolar, from 2 to 5 millimolar.
  15. A kit-of-parts for degrading a vinyl polymer having an initial molar mass in order to form at least one degradation product having a final molar mass lower than the initial molar mass, the kit-of-parts comprising: a) the water-based emulsion of said vinyl polymer; b) at least one enzyme-mediator system comprising: - at least one multi-copper oxidase chosen among a laccase, a laccase-ferroxidase, a laccase-like multi-copper oxidase or a mixture thereof; - at least one respective mediator; and - optionally, at least one additional vinylic monomer, wherein the multi-copper oxidase and the mediator are either intended to be mixed separately with the water-based emulsion or provided as a pre-mix preserved under anaerobic conditions, until being mixed with the water-based emulsion.

Description

TECHNICAL FIELD OF THE INVENTION The invention relates to biotechnological methods for recycling synthetic polymers and more particularly to a method for degrading a vinyl polymer and to a corresponding kit-of-parts. BACKGROUND OF THE INVENTION Plastic polymers are inexpensive and robust materials that can be used in a wide variety of applications, as among others packaging, insulation materials for the construction industry and electronics. However, due to their low biodegradability, some synthetic polymers induce pollution that may damage the environment and/or human health and impact the ecological cycle. Vinyl polymers, such as polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) or polystyrene (PS), are in particular implemented in single-use products and thus contribute to plastic pollution. Notably, PS is one of the most common polymers used to make plastics, the global PS market stood at approximately 11 million tons in 2022 and is expected to grow at a steady CAGR of 6.02% during the forecast period until 2030. The transformation or modification of vinyl polymers, at the design stage or after use, in view of their recycling, is to date mainly limited to physicochemical and/or mechanical processes on an industrial scale. Mechanical methods for plastics recycling most often require important amounts of energy and lead to recycled polymers of lower quality than virgin polymers. Hence, there is a need for efficient methods enabling the recycling of vinyl polymers under low-energy consumption and/or eco-friendly conditions. Academic research has brought out biotechnological methods for recycling synthetic polymers, these methods exploiting the potential of enzymes and microorganisms. The article Biodegradation of polyethylene and polystyrene: From microbial deterioration to enzyme discovery, Y. Zhang et al., Biotechnology Advances, Volume 60, 2022, 107991, ISSN 0734-9750, reviews fungi species allowing biodegradation of PS. This article highlights that the hydrophobic nature of polystyrene still limits the efficiency of its enzymatic degradation. The article Investigation of Abortiporus biennis lignocellulolytic toolbox, and the role of laccases in polystyrene degradation, A. Zerva et al., Chemosphere, Volume 312, Part 1, 2023, 137338, ISSN 0045-6535, describes the effect of a laccase from the white rot fungus Abortiporus biennis on a polystyrene powder. A decrease of the number average molar mass (Mn) and mass average molar mass (Mw) of 19.7% ± 2.9% and 7.7 ± 1.5%, respectively, which corresponds to only a 1.2-fold decrease of Mn, is described in this article. Such a decrease is clearly insufficient for solving the technical problem of PS recycling. Furthermore, this article provides very little insights, on how to operate the enzymatic system as the reaction parameters were not investigated. Hence, the aim of the invention is to provide a method allowing further degradation of a vinyl polymer that can be upcycled and/or recycled, with low energy consumption and low environmental impact, and that can be implemented at an industrial scale, in order to form degradation products of added value. SUMMARY OF THE INVENTION To this end, the invention relates to a method for degrading a vinyl polymer having an initial molar mass in order to form at least one degradation product having a final molar mass lower than the initial molar mass, the method comprising the following steps: a) providing a water-based emulsion of the vinyl polymer;b) mixing the water-based emulsion with at least one enzyme-mediator system to obtain a reaction mixture, said at least one enzyme-mediator system comprising: at least one multi-copper oxidase chosen among a laccase, a laccase-ferroxidase, a laccase-like multi-copper oxidase or a mixture thereof, andat least one mediator,said at least one multi-copper oxidase and said at least one respective mediator being: mixed sequentially with the water-based emulsion, orprovided as a pre-mix preserved under anaerobic conditions, until being mixed with the water-based emulsion;c) stirring the reaction mixture under an atmosphere comprising dioxygen; andd) recovering the at least one degradation product of the vinyl polymer. The inventors have observed that the provision of the vinyl polymer in the form of a water-based emulsion or equivalently in the form of a polymer latex, and the mixing of said water-based emulsion with, sequentially or as a pre-mix under anaerobic conditions, a multi-copper oxidase chosen among a laccase, a laccase-ferroxidase and a laccase-like multi-copper oxidase or a mixture thereof, and an mediator, allows achieving extensive degradation of the initial vinyl polymer, and in particular of PS. In particular, as specified later, the relative variation of molar mass between the initial polymer and any of the at least one degradation product can reach up from 10 to, but not including, 100%, more preferably 50 to, but not including, 100%, even more preferably 90