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Lohmann V, Jones GR, Truong NP, Anastasaki A. The thermodynamics and kinetics of depolymerization: what makes vinyl monomer regeneration feasible? Chem Sci 2024; 15:832-853. [PMID: 38239674 PMCID: PMC10793647 DOI: 10.1039/d3sc05143a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 11/28/2023] [Indexed: 01/22/2024] Open
Abstract
Depolymerization is potentially a highly advantageous method of recycling plastic waste which could move the world closer towards a truly circular polymer economy. However, depolymerization remains challenging for many polymers with all-carbon backbones. Fundamental understanding and consideration of both the kinetics and thermodynamics are essential in order to develop effective new depolymerization systems that could overcome this problem, as the feasibility of monomer generation can be drastically altered by tuning the reaction conditions. This perspective explores the underlying thermodynamics and kinetics governing radical depolymerization of addition polymers by revisiting pioneering work started in the mid-20th century and demonstrates its connection to exciting recent advances which report depolymerization reaching near-quantitative monomer regeneration at much lower temperatures than seen previously. Recent catalytic approaches to monomer regeneration are also explored, highlighting that this nascent chemistry could potentially revolutionize depolymerization-based polymer recycling in the future.
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Affiliation(s)
- Victoria Lohmann
- Laboratory of Polymeric Materials, Department of Materials, ETH Zürich Vladimir-Prelog-Weg 5 8093 Zürich Switzerland
| | - Glen R Jones
- Laboratory of Polymeric Materials, Department of Materials, ETH Zürich Vladimir-Prelog-Weg 5 8093 Zürich Switzerland
| | - Nghia P Truong
- Laboratory of Polymeric Materials, Department of Materials, ETH Zürich Vladimir-Prelog-Weg 5 8093 Zürich Switzerland
- Monash Institute of Pharmaceutical Sciences, Monash University 399 Royal Parade Parkville VIC 3152 Australia
| | - Athina Anastasaki
- Laboratory of Polymeric Materials, Department of Materials, ETH Zürich Vladimir-Prelog-Weg 5 8093 Zürich Switzerland
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2
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Bellotti V, Wang HS, Truong NP, Simonutti R, Anastasaki A. Temporal Regulation of PET-RAFT Controlled Radical Depolymerization. Angew Chem Int Ed Engl 2023; 62:e202313232. [PMID: 37814385 DOI: 10.1002/anie.202313232] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Indexed: 10/11/2023]
Abstract
A photocatalytic RAFT-controlled radical depolymerization method is introduced for precisely conferring temporal control under visible light irradiation. By regulating the deactivation of the depropagating chains and suppressing thermal initiation, an excellent temporal control was enabled, exemplified by several consecutive "on" and "off" cycles. Minimal, if any, depolymerization could be observed during the dark periods while the polymer chain-ends could be efficiently re-activated and continue to depropagate upon re-exposure to light. Notably, favoring deactivation resulted in the gradual unzipping of polymer chains and a stepwise decrease in molecular weight over time. This synthetic approach constitutes a simple methodology to modulate temporal control during the chemical recycling of RAFT-synthesized polymers while offering invaluable mechanistic insights.
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Affiliation(s)
- Valentina Bellotti
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg-5, Zurich, 8093, Switzerland
- Department of Material Science, Università di Milano-Bicocca, Via Roberto Cozzi 55, Milan, 20125, Italy
| | - Hyun Suk Wang
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg-5, Zurich, 8093, Switzerland
| | - Nghia P Truong
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg-5, Zurich, 8093, Switzerland
| | - Roberto Simonutti
- Department of Material Science, Università di Milano-Bicocca, Via Roberto Cozzi 55, Milan, 20125, Italy
| | - Athina Anastasaki
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg-5, Zurich, 8093, Switzerland
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3
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Parkatzidis K, Truong NP, Matyjaszewski K, Anastasaki A. Photocatalytic ATRP Depolymerization: Temporal Control at Low ppm of Catalyst Concentration. J Am Chem Soc 2023; 145:21146-21151. [PMID: 37737835 PMCID: PMC10557129 DOI: 10.1021/jacs.3c05632] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Indexed: 09/23/2023]
Abstract
A photocatalytic ATRP depolymerization is introduced that significantly suppresses the reaction temperature from 170 to 100 °C while enabling temporal regulation. In the presence of low-toxicity iron-based catalysts and under visible light irradiation, near-quantitative monomer recovery could be achieved (up to 90%), albeit with minimal temporal control. By employing ppm concentrations of either FeCl2 or FeCl3, the depolymerization during the dark periods could be completely eliminated, thus enabling temporal control and the possibility to modulate the rate by simply turning the light "on" and "off". Notably, our approach allowed preservation of the end-group fidelity throughout the reaction, could be carried out at high polymer loadings (up to 2M), and was compatible with various polymers and light sources. This methodology provides a facile, environmentally friendly, and temporally regulated route to chemically recycle ATRP-synthesized polymers, thus opening the door for further opportunities.
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Affiliation(s)
- Kostas Parkatzidis
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, Zurich 8093, Switzerland
| | - Nghia P. Truong
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, Zurich 8093, Switzerland
| | - Krzysztof Matyjaszewski
- Department
of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Athina Anastasaki
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, Zurich 8093, Switzerland
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Huang S, Zheng J, Jiang Z, Liu J, Liu Y. Exploring the supramolecular chemistry of cyclopropeniums: halogen-bonding-induced electrostatic assembly of polymers. Chem Sci 2023; 14:9820-9826. [PMID: 37736651 PMCID: PMC10510819 DOI: 10.1039/d3sc03086e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/16/2023] [Indexed: 09/23/2023] Open
Abstract
Exploring new noncovalent synthons for supramolecular assembly is essential for material innovation. Accordingly, we herein report a unique type of cyclopropenium-based supramolecular motif and demonstrate its applications to polymer self-assembly. Because of the "ion pair strain" effect, trisaminocyclopropenium iodides complex strongly with fluoroiodobenzene derivatives, forming stable adducts. Crystal structure analysis reveals that halogen-bonding between the iodide anion and the iodo substituent of the fluoroiodobenzene is the driving force for the formation of these electrostatically complexed adducts. Such halogen-bonding-induced electrostatic interactions were further successfully applied to drive the assembly of polymers in solution, on surfaces, and in bulk, demonstrating their potential for constructing supramolecular polymeric materials.
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Affiliation(s)
- Shiwen Huang
- South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology Guangzhou 510640 China
| | - Jianlin Zheng
- South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology Guangzhou 510640 China
| | - Zihao Jiang
- South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology Guangzhou 510640 China
| | - Jiaxiong Liu
- South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology Guangzhou 510640 China
| | - Yiliu Liu
- South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology Guangzhou 510640 China
- Guangdong Provincial Key Laboratory of Functional and Intelligent Hybrid Materials and Devices, South China University of Technology Guangzhou 510640 China
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5
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Häfliger F, Truong NP, Wang HS, Anastasaki A. Fate of the RAFT End-Group in the Thermal Depolymerization of Polymethacrylates. ACS Macro Lett 2023; 12:1207-1212. [PMID: 37615956 PMCID: PMC10515620 DOI: 10.1021/acsmacrolett.3c00418] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 08/21/2023] [Indexed: 08/25/2023]
Abstract
Thermal RAFT depolymerization has recently emerged as a promising methodology for the chemical recycling of polymers. However, while much attention has been given to the regeneration of monomers, the fate of the RAFT end-group after depolymerization has been unexplored. Herein, we identify the dominant small molecules derived from the RAFT end-group of polymethacrylates. The major product was found to be a unimer (DP = 1) RAFT agent, which is not only challenging to synthesize using conventional single-unit monomer insertion strategies, but also a highly active RAFT agent for methyl methacrylate, exhibiting faster consumption and yielding polymers with lower dispersities compared to the original, commercially available 2-cyano-2-propyl dithiobenzoate. Solvent-derived molecules were also identified predominantly at the beginning of the depolymerization, thus suggesting a significant mechanistic contribution from the solvent. Notably, the formation of both the unimer and the solvent-derived products remained consistent regardless of the RAFT agent, monomer, or solvent employed.
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Affiliation(s)
- Florian Häfliger
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich, Switzerland
| | - Nghia P. Truong
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich, Switzerland
- Monash
Institute of Pharmaceutical Sciences, Monash
University, 399 Royal
Parade, Parkville, VIC 3152, Australia
| | - Hyun Suk Wang
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich, Switzerland
| | - Athina Anastasaki
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich, Switzerland
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Jones GR, Wang HS, Parkatzidis K, Whitfield R, Truong NP, Anastasaki A. Reversed Controlled Polymerization (RCP): Depolymerization from Well-Defined Polymers to Monomers. J Am Chem Soc 2023; 145:9898-9915. [PMID: 37127289 PMCID: PMC10176471 DOI: 10.1021/jacs.3c00589] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Controlled polymerization methods are well-established synthetic protocols for the design and preparation of polymeric materials with a high degree of precision over molar mass and architecture. Exciting recent work has shown that the high end-group fidelity and/or functionality inherent in these techniques can enable new routes to depolymerization under relatively mild conditions. Converting polymers back to pure monomers by depolymerization is a potential solution to the environmental and ecological concerns associated with the ultimate fate of polymers. This perspective focuses on the emerging field of depolymerization from polymers synthesized by controlled polymerizations including radical, ionic, and metathesis polymerizations. We provide a critical review of current literature categorized according to polymerization technique and explore numerous concepts and ideas which could be implemented to further enhance depolymerization including lower temperature systems, catalytic depolymerization, increasing polymer scope, and controlled depolymerization.
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Affiliation(s)
- Glen R Jones
- Laboratory for Polymeric Materials, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Hyun Suk Wang
- Laboratory for Polymeric Materials, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Kostas Parkatzidis
- Laboratory for Polymeric Materials, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Richard Whitfield
- Laboratory for Polymeric Materials, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Nghia P Truong
- Laboratory for Polymeric Materials, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Athina Anastasaki
- Laboratory for Polymeric Materials, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
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7
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Bellotti V, Parkatzidis K, Wang HS, De Alwis Watuthanthrige N, Orfano M, Monguzzi A, Truong NP, Simonutti R, Anastasaki A. Light-accelerated depolymerization catalyzed by Eosin Y. Polym Chem 2023; 14:253-258. [PMID: 36760607 PMCID: PMC9843692 DOI: 10.1039/d2py01383e] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022]
Abstract
Retrieving the starting monomers from polymers synthesized by reversible deactivation radical polymerization has recently emerged as an efficient way to increase the recyclability of such materials and potentially enable their industrial implementation. To date, most methods have primarily focused on utilizing high temperatures (typically from 120 °C to 180 °C) to trigger an efficient depolymerization reaction. In this work, we show that, in the presence of Eosin Y under light irradiation, a much faster depolymerization of polymers made by reversible addition-fragmentation chain-transfer (RAFT) polymerization can be triggered even at a lower temperature (i.e. 100 °C). For instance, green light, in conjunction with ppm amounts of Eosin Y, resulted in the accelerated depolymerization of poly(methyl methacrylate) from 16% (thermal depolymerization at 100 °C) to 37% within 1 hour, and finally 80% depolymerization after 8 hours, as confirmed by both 1H-NMR and SEC analyses. The enhanced depolymerization rate was attributed to the activation of a macroCTA by Eosin Y, thus resulting in a faster macroradical generation. Notably, this method was found to be compatible with different wavelengths (e.g. blue, red and white light irradiation), solvents, and RAFT agents, thus highlighting the potential of light to significantly improve current depolymerization approaches.
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Affiliation(s)
- Valentina Bellotti
- Department of Material Science, University of Milano-Bicocca Via R. Cozzi 55 20125 Milan Italy
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich Vladimir-Prelog-Weg-5 Zurich Switzerland
| | - Kostas Parkatzidis
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich Vladimir-Prelog-Weg-5 Zurich Switzerland
| | - Hyun Suk Wang
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich Vladimir-Prelog-Weg-5 Zurich Switzerland
| | | | - Matteo Orfano
- Department of Material Science, University of Milano-Bicocca Via R. Cozzi 55 20125 Milan Italy
| | - Angelo Monguzzi
- Department of Material Science, University of Milano-Bicocca Via R. Cozzi 55 20125 Milan Italy
| | - Nghia P Truong
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich Vladimir-Prelog-Weg-5 Zurich Switzerland
| | - Roberto Simonutti
- Department of Material Science, University of Milano-Bicocca Via R. Cozzi 55 20125 Milan Italy
| | - Athina Anastasaki
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich Vladimir-Prelog-Weg-5 Zurich Switzerland
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