Carbonatation of [ethylene-glycidyl methacrylate]-based copolymers with carbon dioxide as a reagent: from batch to solvent-free reactive extrusion

• Published in: Green chemistry : an international journal and green chemistry resource : GC Vol. 25; no. 16; pp. 6355 - 6364
• Main Authors: Guerdener, Bruno, Ayzac, Virgile, Norsic, Sébastien, Besognet, Paul, Bounor-Legaré, Véronique, Monteil, Vincent, Dufaud, Véronique, Raynaud, Jean, Chalamet, Yvan
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 14.08.2023
• Subjects: Ammonium; Ammonium salts; Batch reactors; Carbon dioxide; Carbonatation; Carbonates; Catalysts; Chemical Sciences; Continuous extrusion; Copolymers; Epoxides; Ethylene; Flow rates; Green chemistry; Optimization; Polymer melts; Polymers; Quaternary ammonium salts; Reaction kinetics; Reagents; Solvents; Sustainability; Toluene; Twin screw extruders
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/d3gc01127e

The carbonatation of semi-crystalline [ethylene-glycidyl methacrylate]-based polymers (Lotader® grades) was achieved using carbon dioxide as a reagent and quaternary ammonium salts as organocatalysts to transform the polymers' epoxide pendant groups into cyclic carbonate moieties. A batch reactor allowed us to assess the kinetics, dependence on a catalyst and overall potential of this carbonatation. The influence of the ammonium salt composition (anion/cation) was studied in toluene at 110 °C to circumvent the high melting temperatures of these ethylene unit-rich copolymers and obtain a homogeneous medium. The amount of catalyst, CO 2 pressure and temperature were also optimized (TBAB, 5 mol% vs. epoxy content, 4.0 MPa, 110 °C) to allow for quantitative conversion of epoxides into cyclic carbonates. Subsequently, the reaction was transposed, for the 1 st time, to reactive extrusion under CO 2 using a dedicated co-rotating twin-screw extruder to allow for CO 2 containment within the polymer melt. This solvent-free reactive process is perfectly adapted to semi-crystalline and/or high- T g polymers. After optimization, a yield of up to 78% of cyclic carbonate, in addition to orthogonal epoxide, could be obtained with THAB (7.5 mol% vs. epoxy content, ∼30 g h −1 of cat.) at 150 °C with an industry-compliant polymer flow rate of 2 kg h −1 . The respective reactivities of Lotader® grades were compared in batch and in an extruder, unveiling this trend towards carbonatation: AX8840 < AX8700 < AX8900. Sustainability and enhanced productivity of the carbonatation methodology developed herein relies on the use of CO 2 as a C1 reagent for the functionalization of epoxide-bearing polymers harnessing a continuous and clean reactive extrusion process allowing, in a single operation and a few minutes, the production of functional polymers at the kilogram scale under solvent-free conditions. The carbonatation of semi-crystalline [ethylene-glycidyl methacrylate] copolymers was achieved in batch and solvent-free reactive extrusion processes. Using CO 2 as reagent and ammonium salts as catalysts, we turn the epoxides into cyclic carbonates.