Nghia Truong Phuoc

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Truong Phuoc

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Nghia

ORCID

0000-0001-9900-2644

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Publications 1 - 10 of 22

Chemical recycling of bromine-terminated polymers synthesized by ATRP
Mountaki, Styliani; Whitfield, Richard Bradley; Parkatzidis, Kostas; et al. (2024)
RSC Applied Polymers
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.
Visible light-triggered depolymerization of commercial polymethacrylates
Wang, Hyun Suk; Agrachev, Mikhail; Kim, Hongsik; et al. (2025)
Science
The reversion of vinyl polymers with carbon-carbon backbones to their monomers represents an ideal path to alleviate the growing plastic waste stream. However, depolymerizing such stable materials remains a challenge, with state-of-the-art methods relying on “designer” polymers that are neither commercially produced nor suitable for real-world applications. In this work, we report a main chain–initiated, visible light–triggered depolymerization directly applicable to commercial polymers containing undisclosed impurities (e.g., comonomers, additives, or dyes). By in situ generation of chlorine radicals directly from the solvent, near-quantitative (>98%) depolymerization of polymethacrylates could be achieved regardless of their synthetic route (e.g., radical or ionic polymerization), end group, and molecular weight (up to 1.6 million daltons). The possibility to perform multigram-scale depolymerizations and confer temporal control renders this methodology a versatile and general route to recycling.
Understanding dispersity control in photo-atom transfer radical polymerization: Effect of degree of polymerization and kinetic evaluation
Rolland, Manon; Lohmann, Victoria; Whitfield, Richard Bradley; et al. (2021)
Journal of Polymer Science
In photo-atom transfer radical polymerization (ATRP), dispersity can be efficiently controlled by varying the deactivator concentration. In this work, we provide mechanistic insight into dispersity-controlled photo-ATRP by conducting detailed kinetics under a range of conditions. For the lower dispersity polymers, a conventional first-order kinetic profile was observed accompanied by a linear evolution of number average molecular weight (Mn) with conversion while the reactions reached moderate to high conversions (between 66% and 93%). Whereas, when polymers of high dispersity were targeted, the Mn remained relatively constant throughout the polymerization and the reactions ceased at less than 50% of conversion. In particular, for Ð = 1.84, a significant deviation between theoretical and experimental molecular weights was evident. This deviation was unambiguously attributed to slow initiation as indicated by 1H NMR, where significant percentages of unreacted initiator were observed. Importantly, the addition of ligand at the polymerization plateau re-initiated the polymerization and led to the complete consumption of the unreacted initiator, thus enabling the synthesis of one-pot diblock copolymers. We subsequently evaluated the effect of the degree of polymerization (DP) on the obtained dispersity when a constant catalyst ratio was maintained. Based on the interpolation of those experiments results, we could predict experimental conditions for any desirable DPs and dispersities.
Controlling polymer dispersity using switchable RAFT agents: Unravelling the effect of the organic content and degree of polymerization
Antonopoulou, Maria-Nefeli; Whitfield, Richard Bradley; Truong Phuoc, Nghia; et al. (2022)
European Polymer Journal
Dispersity can significantly affect material properties and related applications and as such is a significant parameter to control in polymer design. Switchable RAFT agents were recently utilized as an efficient tool to tailor polymer dispersity. In this work, we investigate the effect of the organic solvent and targeted degree of polymerization (DP) in attaining dispersity-controlled homopolymers and block copolymers. By varying the addition of acid in pure aqueous media we found that a dispersity range between 1.16 and 1.58 could be obtained while the gradual incorporation of the organic content led to broader dispersity ranges. Pleasingly, when the polymerizations were performed in aqueous media, dispersity could be efficiently controlled regardless of the targeted degree of polymerization (from DP 50 to DP 800). Instead, in mixtures containing [DMF]:[H2O] = 4:1, dispersity could be successfully tailored only up to DP = 200 while for higher targeted DPs, a reduction in the final dispersity was not feasible. To expand the scope of our system, we subsequently exploited alternative organic solvents including DMAc, dioxane, DMSO, and ACN. While DMAc showed a side reaction attributed to the high amounts of acid employed, the other solvents successfully resulted in an efficient control over dispersity with ACN requiring the lowest amount of acid to achieve the lowest dispersity value (i.e. 2 equivalents of acid yielded D ~ 1.19). Notably, the highest D polymers synthesized in the various solvents displayed very high end group fidelity as characterized by mass-spectrometry and in-situ chain extensions. After establishing optimal reaction conditions, we also synthesized a range of exemplary diblock and triblock copolymers (with alternating low and high D) demonstrating excellent dispersity control upon subsequent block additions.
Controlling primary chain dispersity in network polymers: elucidating the effect of dispersity on degradation†
Shimizu, Takanori; Whitfield, Richard Bradley; Jones, Glen R.; et al. (2023)
Chemical Science
Although dispersity has been demonstrated to be instrumental in determining many polymer properties, current synthetic strategies predominantly focus on tailoring the dispersity of linear polymers. In contrast, controlling the primary chain dispersity in network polymers is much more challenging, in part due to the complex nature of the reactions, which has limited the exploration of properties and applications. Here, a one-step method to prepare networks with precisely tuned primary chain dispersity is presented. By using an acid-switchable chain transfer agent and a degradable crosslinker in PET-RAFT polymerization, the in situ crosslinking of the propagating polymer chains was achieved in a quantitative manner. The incorporation of a degradable crosslinker, not only enables the accurate quantification of the various primary chain dispersities, post-synthesis, but also allows the investigation and comparison of their respective degradation profiles. Notably, the highest dispersity networks resulted in a 40% increase in degradation time when compared to their lower dispersity analogues, demonstrating that primary chain dispersity has a substantial impact on the network degradation rate. Our experimental findings were further supported by simulations, which emphasized the importance of higher molecular weight polymer chains, found within the high dispersity materials, in extending the lifetime of the network. This methodology presents a new and promising avenue to precisely tune primary chain dispersity within networks and demonstrates that polymer dispersity is an important parameter to consider when designing degradable materials.
Controlling dispersity in aqueous atom transfer radical polymerization: rapid and quantitative synthesis of one-pot block copolymers
Wang, Hyun Suk; Parkatzidis, Kostas; Harrisson, Simon; et al. (2022)
Chimia
Reversed Controlled Polymerization (RCP): Depolymerization from Well-Defined Polymers to Monomers
Jones, Glen R.; Wang, Hyun Suk; Parkatzidis, Kostas; et al. (2023)
Journal of the American Chemical Society
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.
Near-Quantitative, Catalyst-Free Depolymerization of RAFT Polymethacrylates
Wang, Hyun Suk; Truong Phuoc, Nghia; Anastasaki, Athina (2022)
Chimia
Investigating the Effect of End-Group, Molecular Weight, and Solvents on the Catalyst-Free Depolymerization of RAFT Polymers: Possibility to Reverse the Polymerization of Heat-Sensitive Polymers
Wang, Hyun Suk; Truong Phuoc, Nghia; Jones, Glen R.; et al. (2022)
ACS Macro Letters
Reversing reversible deactivation radical polymerization (RDRP) to regenerate the original monomer is an attractive prospect for both fundamental research and industry. However, current depolymerization strategies are often applied to highly heat-tolerant polymers with a specific end-group and can only be performed in a specific solvent. Herein, we depolymerize a variety of poly(methyl methacrylate) materials made by reversible addition-fragmentation chain-transfer (RAFT) polymerization and terminated by various end groups (dithiobenzoate, trithiocarbonate, and pyrazole carbodithioate). The effect of the nature of the solvent on the depolymerization conversion was also investigated, and key solvents such as dioxane, xylene, toluene, and dimethylformamide were shown to facilitate efficient depolymerization reactions. Notably, our approach could selectively regenerate pure heat-sensitive monomers (e.g., tert-butyl methacrylate and glycidyl methacrylate) in the absence of previously reported side reactions. This work pushes the boundaries of reversing RAFT polymerization and considerably expands the chemical toolbox for recovering starting materials under relatively mild conditions.
Cu(0)-RDRP of acrylates using an alkyl iodide initiator
Parkatzidis, Kostas; de Haro Amez, Leonardo; Truong Phuoc, Nghia; et al. (2023)
Polymer Chemistry
In the vast majority of atom transfer radical polymerizations, alkyl bromides or alkyl chlorides are commonly employed as initiators, and minimal attention has been given to alkyl iodides. Herein, we report the room temperature Cu(0)-mediated reversible deactivation radical polymerization of acrylates utilizing alkyl iodide as an initiator. Kinetic experiments were conducted showing a linear dependence of M-n with conversion, good agreement between theoretical and experimental molecular weights, and low dispersity values (D similar to 1.05), even at high monomer conversions. The high-end group fidelity of the iodide-terminated polymer was confirmed via MALDI-ToF-MS analysis and successful in situ chain extensions at near-quantitative conversions. Polymerization of methyl acrylate with various targeted degrees of polymerizations (DPn = 25-2400), resulted in the synthesis of well-defined polymers with low dispersities (D < 1.15), even at higher molecular weights (e.g. M-n = 200 000, D similar to 1.13). The compatibility of the methodology with various solvents, including acetonitrile (MeCN), dimethylformamide (DMF), acetone, and isopropanol (IPA) as well as a range of acrylic monomers was also investigated yielding polymers with excellent control over the molar mass distributions. A series of block copolymers consisting of different block segments were also synthesized in one pot without any intermediate purification steps, thus highlighting the potential of an alkyl iodide initiator in a controlled polymerization.

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