Reversed Controlled Polymerization (RCP): Depolymerization from Well-Defined Polymers to Monomers

Jones, Glen R.; Wang, Hyun Suk; Parkatzidis, Kostas; Whitfield, Richard; Truong, Nghia P.; Anastasaki, Athina

doi:10.1021/jacs.3c00589

Cited by 77 publications

(67 citation statements)

References 109 publications

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“…In contrast, the design of depolymerizable polymers formed by addition across a C–C π bond, such as HDPE and i PP, poses a substantial challenge due their generally higher hydrolytic and thermodynamic stability . Nevertheless, over the past several years, it has been demonstrated that some specific C–C backbones, such as poly(methyl methacrylate) (PMMA) ( T c of 205 and 296 °C at 1.0 and 9.35 M (bulk), respectively), prepared by controlled polymerization can be depolymerized under moderate conditions, presenting exciting opportunities for further innovations . This depolymerizability arises from the high-fidelity end-group functionality achieved through polymerization techniques including atom transfer radical polymerization (ATRP) and reversible addition–fragmentation chain-transfer (RAFT) polymerization …”

Section: Recent Developments In Depolymerizable Backbonesmentioning

confidence: 99%

Emerging Trends in the Chemistry of End-to-End Depolymerization

Deng,

Gillies

2023

JACS Au

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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 (T c ). 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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Section: Recent Developments In Depolymerizable Backbonesmentioning

confidence: 99%

Emerging Trends in the Chemistry of End-to-End Depolymerization

Deng,

Gillies

2023

JACS Au

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“…Although pyrolysis of PMMA was reported to reach near-quantitative monomer recovery at 400–525 °C, very complex reactors were required to reduce the PMMA’s residence time within the reactor and prevent the primary radical species from undergoing side reactions. − Recently, unzipping depolymerization of polymethacrylates was observed via reversible activation of the terminal C–X group (X = halogen or thioester). However, this approach requires high-end-group fidelity to achieve high efficiency, which would sacrifice molecular weight ( M n < 10 4 g/mol for PMMA) and material performance. − …”

Section: Introductionmentioning

confidence: 99%

SaBOX/Copper-Catalyzed Synthesis, Degradation, and Upcycling of a PMMA-Based Copolymer

Ma,

Zhao,

Yang

et al. 2023

Macromolecules

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The development of sustainable vinyl polymers that can be chemically recycled or upcycled is highly required but very challenging. Herein, we report the efficient synthesis, degradation, and upcycling of a high-molecular-weight PMMA-based copolymer completely made of a C−C-bonded backbone enabled by the same catalytic system (SaBOX/copper) under mild conditions for the first time. The atom transfer radical copolymerization (ATRcP) of MMA with α-chloroacrylate is conducted at 30 °C by the catalyst, producing linear PMMA with C−Cl bonds, which are thermally stable below 200 °C with T g of 126 °C, exhibiting the thermophysical properties of commodity PMMA. At a higher temperature (≥65 °C), the catalyst could stimulate degradation at the position of the C−Cl bond, and the polymer chain is cleaved to give telechelic PMMA blocks with functional terminals. Remarkably, these blocks could be employed to readily prepare their parent copolymer, linear block copolymer, or novel branched block copolymer in the presence of a catalyst, realizing the chemical upcycling of a PMMA-based copolymer. Above all, catalysis plays a decisive role in these achievements, and strong catalyst effects are observed in the synthesis of degradable polymers, the degradation reactions, the structure of degradation products, and thus their upcycling. The SaBOX/copper catalytic system shows significant superiority over the copper catalysts commonly used in the literature.

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“…In terms of kinetics, the continuous consumption or formation of a monomer requires active chain ends. Therefore, controlled radical polymerization (CRP), also termed reversible deactivation radical polymerization (RDRP), emerges as a powerful tool for efficient depolymerization at moderately lower temperatures because of the preservation of the chain-end functionality (CEF), which can be harnessed to generate active radicals. , …”

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confidence: 99%

“…Among various RDRP methods, Atom Transfer Radical Polymerization (ATRP) and Reversible Addition–Fragmentation chain-Transfer (RAFT) polymerization techniques are most often used to prepare well-defined polymers with low dispersity. − While RAFT polymers mainly bear dithiocarbonates, trithiocarbonates, and xanthates at their ω-chain ends, polymers prepared by ATRP contain halogens (i.e., Cl and Br) at the ω-chain ends. Polymethacrylates prepared by ATRP or RAFT have been depolymerized using various activators and/or catalysts at elevated temperatures. , Since the polymerization of monomers with bulky substituents is thermodynamically less favorable than those with the smaller ones, their depolymerization can be conducted at lower temperatures. Indeed, the first examples using ATRP were reported for limited/equilibrated polymerization of methacrylates with bulky POSS (polyhedral oligomeric silsesquioxanes) and then for depolymerization of polymethacrylates with large PDMS (poly(dimethylsiloxane)) substituents (up to 79% depolymerization, Scheme A). , …”

mentioning

confidence: 99%

Fast Bulk Depolymerization of Polymethacrylates by ATRP

2023

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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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Reversed Controlled Polymerization (RCP): Depolymerization from Well-Defined Polymers to Monomers

Cited by 77 publications

References 109 publications

Emerging Trends in the Chemistry of End-to-End Depolymerization

Emerging Trends in the Chemistry of End-to-End Depolymerization

SaBOX/Copper-Catalyzed Synthesis, Degradation, and Upcycling of a PMMA-Based Copolymer

Fast Bulk Depolymerization of Polymethacrylates by ATRP

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