Affiliation:
1. Cluster for Advanced Macromolecular Design, School of Chemical Engineering The University of New South Wales Sydney New South Wales Australia
2. School of Chemical Engineering The University of New South Wales Sydney New South Wales Australia
3. CSIRO Manufacturing Bag 10 Clayton South Victoria Australia
4. Materials Research Laboratory and Department of Materials, Chemistry and Biochemistry University of California Santa Barbara California USA
5. Laboratory of Polymeric Materials, Department of Materials ETH Zürich Zürich Switzerland
Abstract
AbstractThe ability to revert polymers to their original monomers represents a crucial chemical recycling technique, promoting sustainability and offering the chance to convert used materials into valuable products. In recent years, numerous studies have explored the use of polymers synthesized via reversible deactivation radical polymerization (RDRP) techniques to facilitate efficient depolymerization reactions. Herein, we report the use of a photocatalyst, zinc tetraphenylporphyrin (ZnTPP), along with light irradiation to accelerate depolymerization of polymers prepared by reversible addition‐fragmentation chain transfer (RAFT) polymerization. We explore various parameters affecting depolymerization efficiency, including solvents, reaction temperature (80, 100, and 120°C), the presence of photocatalysts (ZnTPP and Eosin Y), and the type of RAFT end‐groups, namely trithiocarbonate, dithiobenzoate, and 1H‐pyrazole‐1‐carbodithioate. For instance, when PMMA was diluted to 25 mM in 1,4‐dioxane and heated to 120°C under green light irradiation in the presence of ZnTPP (200 ppm), rapid depolymerization exceeding 70% occurred within 1 h. Without ZnTPP, under similar conditions, the reaction required over 8 h to achieve a slightly lower yield. Furthermore, this method confers moderate oxygen tolerance to the system, enabling depolymerization to proceed without the need of deoxygenation, albeit at a lower rate and consequently lesser monomer recovery (31%).
Funder
Australian Research Council
Life Sciences Division, Army Research Office