1
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Mountaki S, Whitfield R, Liarou E, Truong NP, Anastasaki A. Open-Air Chemical Recycling: Fully Oxygen-Tolerant ATRP Depolymerization. J Am Chem Soc 2024; 146:18848-18854. [PMID: 38958656 PMCID: PMC11258787 DOI: 10.1021/jacs.4c05621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 06/17/2024] [Accepted: 06/24/2024] [Indexed: 07/04/2024]
Abstract
While oxygen-tolerant strategies have been overwhelmingly developed for controlled radical polymerizations, the low radical concentrations typically required for high monomer recovery render oxygen-tolerant solution depolymerizations particularly challenging. Here, an open-air atom transfer radical polymerization (ATRP) depolymerization is presented, whereby a small amount of a volatile cosolvent is introduced as a means to thoroughly remove oxygen. Ultrafast depolymerization (i.e., 2 min) could efficiently proceed in an open vessel, allowing a very high monomer retrieval to be achieved (i.e., ∼91% depolymerization efficiency), on par with that of the fully deoxygenated analogue. Oxygen probe studies combined with detailed depolymerization kinetics revealed the importance of the low-boiling point cosolvent in removing oxygen prior to the reaction, thus facilitating effective open-air depolymerization. The versatility of the methodology was demonstrated by performing reactions with a range of different ligands and at high polymer loadings (1 M monomer repeat unit concentration) without significantly compromising the yield. This approach provides a fully oxygen-tolerant, facile, and efficient route to chemically recycle ATRP-synthesized polymers, enabling exciting new applications.
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Affiliation(s)
- Stella
Afroditi Mountaki
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Zurich 8093, Switzerland
| | - Richard Whitfield
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Zurich 8093, Switzerland
| | - Evelina Liarou
- Department
of Chemistry, University of Warwick Library Road, Coventry CV4 7SH, U.K.
| | - Nghia P. Truong
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Zurich 8093, Switzerland
| | - Athina Anastasaki
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Zurich 8093, Switzerland
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2
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De Alwis Watuthanthrige N, Whitfield R, Harrisson S, Truong NP, Anastasaki A. Thermal Solution Depolymerization of RAFT Telechelic Polymers. ACS Macro Lett 2024; 13:806-811. [PMID: 38857492 PMCID: PMC11256755 DOI: 10.1021/acsmacrolett.4c00286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 06/03/2024] [Accepted: 06/04/2024] [Indexed: 06/12/2024]
Abstract
Thermal solution depolymerization is a promising low-temperature chemical recycling strategy enabling high monomer recovery from polymers made by controlled radical polymerization. However, current methodologies predominantly focus on the depolymerization of monofunctional polymers, limiting the material scope and depolymerization pathways. Herein, we report the depolymerization of telechelic polymers synthesized by RAFT polymerization. Notably, we observed a significant decrease in the molecular weight (Mn) of the polymers during monomer recovery, which contrasts the minimal Mn shift observed during the depolymerization of monofunctional polymers. Introducing Z groups at the center or both ends of the polymer resulted in distinct kinetic profiles, indicating partial depolymerization of the bifunctional polymers, as supported by mathematical modeling. Remarkably, telechelic polymers featuring R-terminal groups showed up to 68% improvement in overall depolymerization conversion compared to their monofunctional analogues, highlighting the potential of these materials in chemical recycling and the circular economy.
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Affiliation(s)
| | - Richard Whitfield
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Zurich, 8093, Switzerland
| | - Simon Harrisson
- Laboratoire
de Chimie des Polymères Organiques, University of Bordeaux/Bordeaux-INP/CNRS UMR5629, Pessac 33607, France
| | - Nghia P. Truong
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Zurich, 8093, Switzerland
| | - Athina Anastasaki
- Laboratory
of Polymeric Materials, Department of Materials, ETH Zurich, Zurich, 8093, Switzerland
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3
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Oh S, Stache EE. Recent advances in oxidative degradation of plastics. Chem Soc Rev 2024; 53:7309-7327. [PMID: 38884337 DOI: 10.1039/d4cs00407h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Oxidative degradation is a powerful method to degrade plastics into oligomers and small oxidized products. While thermal energy has been conventionally employed as an external stimulus, recent advances in photochemistry have enabled photocatalytic oxidative degradation of polymers under mild conditions. This tutorial review presents an overview of oxidative degradation, from its earliest examples to emerging strategies. This review briefly discusses the motivation and the development of thermal oxidative degradation of polymers with a focus on underlying mechanisms. Then, we will examine modern studies primarily relevant to catalytic thermal oxidative degradation and photocatalytic oxidative degradation. Lastly, we highlight some unique studies using unconventional approaches for oxidative polymer degradation, such as electrochemistry.
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Affiliation(s)
- Sewon Oh
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
| | - Erin E Stache
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
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4
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Michelas M, Wimberger L, Boyer C. A General Approach for Photo-Oxidative Degradation of Various Polymers. Macromol Rapid Commun 2024:e2400358. [PMID: 39008823 DOI: 10.1002/marc.202400358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 06/26/2024] [Indexed: 07/17/2024]
Abstract
The escalating demand for plastics has resulted in a surge of plastic waste worldwide, posing a monumental environmental challenge. To address this issue, a versatile photo-oxidative degradation method applicable to seven distinct polymer families is proposed, comprising poly(isobutyl vinyl ether) (PIBVE), poly(2,3-dihydrofuran) (PDHF), poly(vinyl acetate) (PVAc), poly(n-butyl acrylate) (PBA), poly(methyl acrylate) (PMA), poly(vinyl chloride) (PVC), poly(dimethyl acrylamide) (PDMA), poly(ethylene oxide) (PEO), poly(oligo(ethylene glycol) methyl ether acrylate) (PEGMEA), and even poly(methyl methacrylate) (PMMA). This method employs photo-mediated hydrogen atom transfer (HAT) followed by oxidation to promote polymer degradation. This reaction is carried out under aerobic condition in the presence of iron trichloride (FeCl3) as a photocatalyst in combination with low-intensity purple light irradiation. The process can degrade up to 97% of the polymer in less than 3 h. This degradation process can be easily controlled by switching the light off, which allows for precise modulation of the degradation rate, enhancing the effectiveness of the method. Overall, this method provides a sustainable method for degrading various polymer types with low energy input.
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Affiliation(s)
- Maxime Michelas
- School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Laura Wimberger
- School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Cyrille Boyer
- School of Chemical Engineering, University of New South Wales, Sydney, NSW, 2052, Australia
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5
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Xu Z, Sun D, Xu J, Yang R, Russell JD, Liu G. Progress and Challenges in Polystyrene Recycling and Upcycling. CHEMSUSCHEM 2024:e202400474. [PMID: 38757556 DOI: 10.1002/cssc.202400474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 05/16/2024] [Accepted: 05/17/2024] [Indexed: 05/18/2024]
Abstract
Polystyrene is a staple plastic in the packaging and insulation market. Despite its good recyclability, the willingness of PS recycling remains low, largely due to the high recycling cost and limited profitability. This review examines the research progresses, gaps, and challenges in areas that affect the recycling costs, including but not limited to logistics, packaging design, and policymaking. We critically evaluate the recent developments in upcycling strategies, and we particularly focus on tandem and hydrogen-atom transfer (HAT) upcycling strategies. We conclude that future upcycling studies should focus on not only reaction chemistry and mechanisms but also economic viability of the processes. The goal of this review is to stimulate the development of innovative recycling strategies with low recycling costs and high economic output values. We hope to stimulate the economic and technological momentum of PS recycling towards a sustainable and circular economy.
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Affiliation(s)
- Zhen Xu
- School of Chemistry and Chemical Engineering, Northwest Polytechnology University, Xi'an, 710000, China
- Department of Chemistry, Virginia Tech, Blacksburg, VA-24061, US
| | - Dongshi Sun
- School of Information and Business Management, Dalian Neusoft University of Information, Dalian, 116023, China
| | - Jianjun Xu
- Institute of Supply Chain Analytics, Dongbei University of Finance and Economics, Dalian, 116025, China
| | - Rong Yang
- School of Chemistry and Chemical Engineering, Northwest Polytechnology University, Xi'an, 710000, China
| | - Jennifer D Russell
- Department of Chemistry, Virginia Tech, Blacksburg, VA-24061, US
- Department of Sustainable Biomaterials, Virginia Tech, Blacksburg, VA-24061, US
| | - Guoliang Liu
- Department of Chemistry, Virginia Tech, Blacksburg, VA-24061, US
- Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA-24061, US
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6
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Parkatzidis K, Wang HS, Anastasaki A. Photocatalytic Upcycling and Depolymerization of Vinyl Polymers. Angew Chem Int Ed Engl 2024; 63:e202402436. [PMID: 38466624 DOI: 10.1002/anie.202402436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 03/10/2024] [Accepted: 03/11/2024] [Indexed: 03/13/2024]
Abstract
Photocatalytic upcycling and depolymerization of vinyl polymers have emerged as promising strategies to combat plastic pollution and promote a circular economy. This mini review critically summarizes current developments in the upcycling and degradation of vinyl polymers including polystyrene and poly(meth)acrylates. Of these material classes, polymethacrylates possess the unique possibility to undergo a photocatalytic depolymerization back to monomer under thermodynamically favourable conditions, thus presenting significant advantages over traditional thermal strategies. Our perspective on current formidable challenges and potential future directions are also discussed.
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Affiliation(s)
- Kostas Parkatzidis
- Department of Materials Science, ETH Zurich, Vladimir-Prelog-Weg 5, 8093, Zürich, Switzerland
| | - Hyun Suk Wang
- Department of Materials Science, ETH Zurich, Vladimir-Prelog-Weg 5, 8093, Zürich, Switzerland
| | - Athina Anastasaki
- Department of Materials Science, ETH Zurich, Vladimir-Prelog-Weg 5, 8093, Zürich, Switzerland
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7
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Ko K, Lundberg DJ, Johnson AM, Johnson JA. Mechanism-Guided Discovery of Cleavable Comonomers for Backbone Deconstructable Poly(methyl methacrylate). J Am Chem Soc 2024; 146:9142-9154. [PMID: 38526229 DOI: 10.1021/jacs.3c14554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/26/2024]
Abstract
The development of cleavable comonomers (CCs) with suitable copolymerization reactivity paves the way for the introduction of backbone deconstructability into polymers. Recent advancements in thionolactone-based CCs, exemplified by dibenzo[c,e]-oxepine-5(7H)-thione (DOT), have opened promising avenues for the selective deconstruction of multiple classes of vinyl polymers, including polyacrylates, polyacrylamides, and polystyrenics. To date, however, no thionolactone CC has been shown to copolymerize with methacrylates to an appreciable extent to enable polymer deconstruction. Here, we overcome this challenge through the design of a new class of benzyl-functionalized thionolactones (bDOTs). Guided by detailed mechanistic analyses, we find that the introduction of radical-stabilizing substituents to bDOTs enables markedly increased and tunable copolymerization reactivity with methyl methacrylate (MMA). Through iterative optimizations of the molecular structure, a specific bDOT, F-p-CF3PhDOT, is discovered to copolymerize efficiently with MMA. High molar mass deconstructable PMMA-based copolymers (dPMMA, Mn > 120 kDa) with low percentages of F-p-CF3PhDOT (1.8 and 3.8 mol%) are prepared using industrially relevant bulk free radical copolymerization conditions. The thermomechanical properties of dPMMA are similar to PMMA; however, the former is shown to degrade into low molar mass fragments (<6.5 kDa) under mild aminolysis conditions. This work presents the first example of a radical ring-opening CC capable of nearly random copolymerization with MMA without the possibility of cross-linking and provides a workflow for the mechanism-guided design of deconstructable copolymers in the future.
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Affiliation(s)
- Kwangwook Ko
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - David J Lundberg
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Alayna M Johnson
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Jeremiah A Johnson
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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8
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Mountaki SA, Whitfield R, Parkatzidis K, Antonopoulou MN, Truong NP, Anastasaki A. Chemical recycling of bromine-terminated polymers synthesized by ATRP. RSC APPLIED POLYMERS 2024; 2:275-283. [PMID: 38525379 PMCID: PMC10955525 DOI: 10.1039/d3lp00279a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 01/25/2024] [Indexed: 03/26/2024]
Abstract
Chemical recycling of polymers is one of the biggest challenges in materials science. Recently, remarkable achievements have been made by utilizing polymers prepared by controlled radical polymerization to trigger low-temperature depolymerization. However, in the case of atom transfer radical polymerization (ATRP), depolymerization has nearly exclusively focused on chlorine-terminated polymers, even though the overwhelming majority of polymeric materials synthesized with this method possess a bromine end-group. Herein, we report an efficient depolymerization strategy for bromine-terminated polymethacrylates which employs an inexpensive and environmentally friendly iron catalyst (FeBr2/L). The effect of various solvents and the concentration of metal salt and ligand on the depolymerization are judiciously explored and optimized, allowing for a depolymerization efficiency of up to 86% to be achieved in just 3 minutes. Notably, the versatility of this depolymerization is exemplified by its compatibility with chlorinated and non-chlorinated solvents, and both Fe(ii) and Fe(iii) salts. This work significantly expands the scope of ATRP materials compatible with depolymerization and creates many future opportunities in applications where the depolymerization of bromine-terminated polymers is desired.
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Affiliation(s)
- Stella Afroditi Mountaki
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich Vladimir-Prelog-Weg-5 8093 Zurich Switzerland
| | - Richard Whitfield
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich Vladimir-Prelog-Weg-5 8093 Zurich Switzerland
| | - Kostas Parkatzidis
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich Vladimir-Prelog-Weg-5 8093 Zurich Switzerland
| | - Maria-Nefeli Antonopoulou
- 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
| | - Athina Anastasaki
- Laboratory of Polymeric Materials, Department of Materials, ETH Zurich Vladimir-Prelog-Weg-5 8093 Zurich Switzerland
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9
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Wimberger L, Ng G, Boyer C. Light-driven polymer recycling to monomers and small molecules. Nat Commun 2024; 15:2510. [PMID: 38509090 PMCID: PMC10954676 DOI: 10.1038/s41467-024-46656-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 03/05/2024] [Indexed: 03/22/2024] Open
Abstract
Only a small proportion of global plastic waste is recycled, of which most is mechanically recycled into lower quality materials. The alternative, chemical recycling, enables renewed production of pristine materials, but generally comes at a high energy cost, particularly for processes like pyrolysis. This review focuses on light-driven approaches for chemically recycling and upcycling plastic waste, with emphasis on reduced energy consumption and selective transformations not achievable with heat-driven methods. We focus on challenging to recycle backbone structures composed of mainly C‒C bonds, which lack functional groups i.e., esters or amides, that facilitate chemical recycling e.g., by solvolysis. We discuss the use of light, either in conjunction with heat to drive depolymerization to monomers or via photocatalysis to transform polymers into valuable small molecules. The structural prerequisites for these approaches are outlined, highlighting their advantages as well as limitations. We conclude with an outlook, addressing key challenges, opportunities, and provide guidelines for future photocatalyst (PC) development.
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Affiliation(s)
- Laura Wimberger
- Cluster for Advanced Macromolecular Design and School of Chemical Engineering, The University of New South Wales, 2052, Sydney, NSW, Australia
| | - Gervase Ng
- Cluster for Advanced Macromolecular Design and School of Chemical Engineering, The University of New South Wales, 2052, Sydney, NSW, Australia
| | - Cyrille Boyer
- Cluster for Advanced Macromolecular Design and School of Chemical Engineering, The University of New South Wales, 2052, Sydney, NSW, Australia.
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10
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Hughes RW, Lott ME, Zastrow IS, Young JB, Maity T, Sumerlin BS. Bulk Depolymerization of Methacrylate Polymers via Pendent Group Activation. J Am Chem Soc 2024; 146:6217-6224. [PMID: 38382047 DOI: 10.1021/jacs.3c14179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
In this study, we present an efficient approach for the depolymerization of poly(methyl methacrylate) (PMMA) copolymers synthesized via conventional radical polymerization. By incorporating low mol % phthalimide ester-containing monomers during the polymerization process, colorless and transparent polymers closely resembling unfunctionalized PMMA are obtained, which can achieve >95% reversion to methyl methacrylate (MMA). Notably, our catalyst-free bulk depolymerization method exhibits exceptional efficiency, even for high-molecular-weight polymers, including ultrahigh-molecular-weight (106-107 g/mol) PMMA, where near-quantitative depolymerization is achieved. Moreover, this approach yields polymer byproducts of significantly lower molecular weight, distinguishing it from bulk depolymerization methods initiated from chain ends. Furthermore, we extend our investigation to polymethacrylate networks, demonstrating high extents of depolymerization. This innovative depolymerization strategy offers promising opportunities for the development of sustainable polymethacrylate materials, holding great potential for various applications in polymer science.
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Affiliation(s)
- Rhys W Hughes
- George & Josephine Butler Polymer Research Laboratory, Department of Chemistry, Center for Macromolecular Science & Engineering, University of Florida, Gainesville, Florida 32611, United States
| | - Megan E Lott
- George & Josephine Butler Polymer Research Laboratory, Department of Chemistry, Center for Macromolecular Science & Engineering, University of Florida, Gainesville, Florida 32611, United States
| | - Isabella S Zastrow
- George & Josephine Butler Polymer Research Laboratory, Department of Chemistry, Center for Macromolecular Science & Engineering, University of Florida, Gainesville, Florida 32611, United States
| | - James B Young
- George & Josephine Butler Polymer Research Laboratory, Department of Chemistry, Center for Macromolecular Science & Engineering, University of Florida, Gainesville, Florida 32611, United States
| | - Tanmoy Maity
- George & Josephine Butler Polymer Research Laboratory, Department of Chemistry, Center for Macromolecular Science & Engineering, University of Florida, Gainesville, Florida 32611, United States
| | - Brent S Sumerlin
- George & Josephine Butler Polymer Research Laboratory, Department of Chemistry, Center for Macromolecular Science & Engineering, University of Florida, Gainesville, Florida 32611, United States
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11
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Chin M, Yang T, Quirion KP, Lian C, Liu P, He J, Diao T. Implementing a Doping Approach for Poly(methyl methacrylate) Recycling in a Circular Economy. J Am Chem Soc 2024; 146:5786-5792. [PMID: 38382057 PMCID: PMC10921398 DOI: 10.1021/jacs.3c13223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 02/15/2024] [Accepted: 02/16/2024] [Indexed: 02/23/2024]
Abstract
To mitigate pollution by plastic waste, it is paramount to develop polymers with efficient recyclability while retaining desirable physical properties. A recyclable poly(methyl methacrylate) (PMMA) is synthesized by incorporating a minimal amount of an α-methylstyrene (AMS) analogue into the polymer structure. This P(MMA-co-AMS) copolymer preserves the essential mechanical strength and optical clarity of PMMA, vital for its wide-ranging applications in various commercial and high-tech industries. Doping with AMS significantly enhances the thermal, catalyst-free depolymerization efficiency of PMMA, facilitating the recovery of methyl methacrylate (MMA) with high yield and purity at temperatures ranging from 150 to 210 °C, nearly 250 K lower than current industrial standards. Furthermore, the low recovery temperature permits the isolation of pure MMA from a mixture of assorted common plastics.
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Affiliation(s)
- Mason
T. Chin
- Department
of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States
| | - Tiangang Yang
- Department
of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Kevin P. Quirion
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Christina Lian
- Department
of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States
| | - Peng Liu
- Department
of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jie He
- Department
of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
| | - Tianning Diao
- Department
of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States
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12
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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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13
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Hsu JH, Ball TE, Oh S, Stache EE, Fors BP. Selective Electrocatalytic Degradation of Ether-Containing Polymers. Angew Chem Int Ed Engl 2024; 63:e202316578. [PMID: 38032347 DOI: 10.1002/anie.202316578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/28/2023] [Accepted: 11/30/2023] [Indexed: 12/01/2023]
Abstract
Leveraging electrochemistry to degrade robust polymeric materials has the potential to impact society's growing issue of plastic waste. Herein, we develop an electrocatalytic oxidative degradation of polyethers and poly(vinyl ethers) via electrochemically mediated hydrogen atom transfer (HAT) followed by oxidative polymer degradation promoted by molecular oxygen. We investigated the selectivity and efficiency of this method, finding our conditions to be highly selective for polymers with hydridic, electron-rich C-H bonds. We leveraged this reactivity to degrade polyethers and poly(vinyl ethers) in the presence of polymethacrylates and polyacrylates with complete selectivity. Furthermore, this method made polyacrylates degradable by incorporation of ether units into the polymer backbone. We quantified degradation products, identifying up to 36 mol % of defined oxidation products, including acetic acid, formic acid, and acetaldehyde, and we extended this method to degrade a polyether-based polyurethane in a green solvent. This work demonstrates a facile, electrochemically-driven route to degrade polymers containing ether functionalities.
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Affiliation(s)
- Jesse H Hsu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Tyler E Ball
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Sewon Oh
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
| | - Erin E Stache
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Brett P Fors
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14850, USA
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14
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Galan NJ, Cobbold BE, Cromer CE, Brantley JN. Macromolecular Photoediting Using Single-Electron Logic. ACS Macro Lett 2023; 12:1623-1628. [PMID: 37962989 DOI: 10.1021/acsmacrolett.3c00646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
Accessing the chemistry of reactive intermediates under mild conditions has significantly expanded the available chemical space for molecular transformations. Nowhere is this more apparent than in the context of photoredox catalysis. Despite abundant literature precedents for using this powerful methodology to build complex targets, there are comparatively few reports that leverage photoredox catalysis for macromolecular editing. Here, we report a mild photoredox approach that enables both the functionalization and degradation of polyalkenamers to valuable feedstocks. Irradiation with visible light (including natural sunlight) in the presence of a pyrillium photoredox catalyst promoted facile chain scission in a variety of substrates. This metal-free approach transformed high molar mass materials (>300 kDa) to low molar mass species (<15 kDa) within 10 min. Moreover, we could completely degrade macromolecules into a range of useful targets (C16-C29 species) within 96 h. Mechanistic and kinetic experiments were carried out to understand this reactivity, which could be coupled with hydrofunctionalizations to create tailored products.
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Affiliation(s)
- Nicholas J Galan
- The Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Boris E Cobbold
- The Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Chase E Cromer
- The Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Johnathan N Brantley
- The Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
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15
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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: 0] [Impact Index Per Article: 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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16
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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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17
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Deng Z, Gillies ER. Emerging Trends in the Chemistry of End-to-End Depolymerization. JACS AU 2023; 3:2436-2450. [PMID: 37772181 PMCID: PMC10523501 DOI: 10.1021/jacsau.3c00345] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/09/2023] [Accepted: 08/16/2023] [Indexed: 09/30/2023]
Abstract
Over the past couple of decades, polymers that depolymerize end-to-end upon cleavage of their backbone or activation of a terminal functional group, sometimes referred to as "self-immolative" polymers, have been attracting increasing attention. They are of growing interest in the context of enhancing polymer degradability but also in polymer recycling as they allow monomers to be regenerated in a controlled manner under mild conditions. Furthermore, they are highly promising for applications as smart materials due to their ability to provide an amplified response to a specific signal, as a single sensing event is translated into the generation of many small molecules through a cascade of reactions. From a chemistry perspective, end-to-end depolymerization relies on the principles of self-immolative linkers and polymer ceiling temperature (Tc). In this article, we will introduce the key chemical concepts and foundations of the field and then provide our perspective on recent exciting developments. For example, over the past few years, new depolymerizable backbones, including polyacetals, polydisulfides, polyesters, polythioesters, and polyalkenamers, have been developed, while modern approaches to depolymerize conventional backbones such as polymethacrylates have also been introduced. Progress has also been made on the topological evolution of depolymerizable systems, including the introduction of fully depolymerizable block copolymers, hyperbranched polymers, and polymer networks. Furthermore, precision sequence-defined oligomers have been synthesized and studied for data storage and encryption. Finally, our perspectives on future opportunities and challenges in the field will be discussed.
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Affiliation(s)
- Zhengyu Deng
- Department
of Chemistry, The University of Western
Ontario, 1151 Richmond St., London, Ontario N6A 5B7, Canada
| | - Elizabeth R. Gillies
- Department
of Chemistry, The University of Western
Ontario, 1151 Richmond St., London, Ontario N6A 5B7, Canada
- Department
of Chemical and Biochemical Engineering, The University of Western Ontario, 1151 Richmond St., London, Ontario N6A 5B9, Canada
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18
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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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19
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Whitfield R, Jones GR, Truong NP, Manring LE, Anastasaki A. Solvent-Free Chemical Recycling of Polymethacrylates made by ATRP and RAFT polymerization: High-Yielding Depolymerization at Low Temperatures. Angew Chem Int Ed Engl 2023; 62:e202309116. [PMID: 37523176 DOI: 10.1002/anie.202309116] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/31/2023] [Accepted: 07/31/2023] [Indexed: 08/01/2023]
Abstract
Although controlled radical polymerization is an excellent tool to make precision polymeric materials, reversal of the process to retrieve the starting monomer is far less explored despite the significance of chemical recycling. Here, we investigate the bulk depolymerization of RAFT and ATRP-synthesized polymers under identical conditions. RAFT-synthesized polymers undergo a relatively low-temperature solvent-free depolymerization back to monomer thanks to the partial in situ transformation of the RAFT end-group to macromonomer. Instead, ATRP-synthesized polymers can only depolymerize at significantly higher temperatures (>350 °C) through random backbone scission. To aid a more complete depolymerization at even lower temperatures, we performed a facile and quantitative end-group modification strategy in which both ATRP and RAFT end-groups were successfully converted to macromonomers. The macromonomers triggered a lower temperature bulk depolymerization with an onset at 150 °C yielding up to 90 % of monomer regeneration. The versatility of the methodology was demonstrated by a scalable depolymerization (≈10 g of starting polymer) retrieving 84 % of the starting monomer intact which could be subsequently used for further polymerization. This work presents a new low-energy approach for depolymerizing controlled radical polymers and creates many future opportunities as high-yielding, solvent-free and scalable depolymerization methods are sought.
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Affiliation(s)
- Richard Whitfield
- Laboratory of Polymeric Materials, D-MATL, ETH Zurich, Vladimir-Prelog-Weg-5, 8093, Zurich, Switzerland
| | - Glen R Jones
- Laboratory of Polymeric Materials, D-MATL, ETH Zurich, Vladimir-Prelog-Weg-5, 8093, Zurich, Switzerland
| | - Nghia P Truong
- Laboratory of Polymeric Materials, D-MATL, ETH Zurich, Vladimir-Prelog-Weg-5, 8093, Zurich, Switzerland
| | | | - Athina Anastasaki
- Laboratory of Polymeric Materials, D-MATL, ETH Zurich, Vladimir-Prelog-Weg-5, 8093, Zurich, Switzerland
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20
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De Luca
Bossa F, Yilmaz G, Matyjaszewski K. Fast Bulk Depolymerization of Polymethacrylates by ATRP. ACS Macro Lett 2023; 12:1173-1178. [PMID: 37531639 PMCID: PMC10433507 DOI: 10.1021/acsmacrolett.3c00389] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 07/28/2023] [Indexed: 08/04/2023]
Abstract
Fast bulk depolymerization of poly(n-butyl methacrylate) and poly(methyl methacrylate), prepared by atom transfer radical polymerization (ATRP), is reported in the temperature range between 150 and 230 °C. Depolymerization of Cl-terminated polymethacrylates was catalyzed by a CuCl2/TPMA complex (0.022 or 0.22 equiv vs P-Cl) and was studied using TGA, also under isothermal conditions. Relatively rapid 5-20 min depolymerization was observed at 230 and 180 °C. The preparative scale reactions were carried out using a short-path distillation setup with up to 84% depolymerization within 15 min at 230 °C.
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Affiliation(s)
- Ferdinando De Luca
Bossa
- Department
of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Gorkem Yilmaz
- Department
of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
| | - Krzysztof Matyjaszewski
- Department
of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States
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21
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Korpusik AB, Adili A, Bhatt K, Anatot JE, Seidel D, Sumerlin BS. Degradation of Polyacrylates by One-Pot Sequential Dehydrodecarboxylation and Ozonolysis. J Am Chem Soc 2023; 145:10480-10485. [PMID: 37155970 DOI: 10.1021/jacs.3c02497] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We establish a synthetically convenient method to degrade polyacrylate homopolymers. Carboxylic acids are installed along the polymer backbone by partial hydrolysis of the ester side chains, and then, in a one-pot sequential procedure, the carboxylic acids are converted into alkenes and oxidatively cleaved. This process enables the robustness and properties of polyacrylates to be maintained during their usable lifetime. The ability to tune the degree of degradation was demonstrated by varying the carboxylic acid content of the polymers. This method is compatible with a wide range of polymers prepared from vinyl monomers through copolymerization of acrylic acid with different monomers including acrylates, acrylamides, and styrenics.
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Affiliation(s)
- Angie B Korpusik
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Alafate Adili
- Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Kamal Bhatt
- Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Jacqueline E Anatot
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Daniel Seidel
- Center for Heterocyclic Compounds, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Brent S Sumerlin
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
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22
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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: 26] [Impact Index Per Article: 26.0] [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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23
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Bagheri A. Application of RAFT in 3D Printing: Where Are the Future Opportunities? Macromolecules 2023. [DOI: 10.1021/acs.macromol.2c02585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Affiliation(s)
- Ali Bagheri
- School of Science and Technology, University of New England, Armidale, NSW 2351, Australia
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