Controlled Radical Polymerization Research Articles

Highly selective removal of thorium from acidic solutions achieved on phosphonic acid functionalized core–shell magnetic nanocomposite: Understanding adsorption and binding mechanisms

Thorium has received widespread attention as potential nuclear fuel alternative for the next-generation thorium-based molten salt reactors. With the growth of nuclear energy, it is needful to exploit magnetic nanomaterials to remove thorium from aqueous solutions, owing to their superparamagnetism and large specific surface energy. Nevertheless, most of magnetic nanomaterials often suffered from low thorium selectivity and poor structural ability in acidic solutions. Herein, a novel core–shell magnetic nanocomposite Fe3O4@SiO2/P (AA-MMA-VPA) possessing phosphonic acid was developed by a controlled radical polymerization of vinylphosphonic acid (VPA) in the presence of Fe3O4 encapsulated by SiO2 (Fe3O4@SiO2). Due to the presence of the high content of phosphonic acid groups and the absence of any universal groups, Fe3O4@SiO2/P (AA-MMA-VPA) displayed exceptional selectivity for thorium in the presence of 11 co-existing cations. The separation factor STh/M value for Fe3O4@SiO2/P(AA-MMA-VPA) concerning all other competing cations surpassed 74.4, and the largest value for STh/M even amounted to 343.5. Further, Fe3O4@SiO2/P (AA-MMA-VPA) possessed a maximum adsorption capacity (qmax) of 485.4 mg g−1 at pH of 3.0, higher than that of other magnetic sorbents. By reason of its core–shell structure, the sorbent possessed an outstanding structure stability even after immersed into HNO3 solution at pH of 0.5 for 72 h. The sorbent could as well be magnetically recouped, and recycled at least six times without evident diminution in sorption amount. The sterling removal performance of the sorbent was assigned to the interaction of thorium with phosphonic acid, corroborated by FT-IR, XPS and DFT method. Thus, this study affords a new viewpoint for exploiting magnetic nanomaterials with sterling acidic resistance for the strongly selective entrapment of thorium from acidic media.

Synthesis and Reactivity of Diazirine-Containing Polymers via Controlled Radical Polymerization

Synthesis and Reactivity of Diazirine-Containing Polymers via Controlled Radical Polymerization

Mechanically triggered on-demand degradation of polymers synthesized by radical polymerizations

Polymers that degrade on demand have the potential to facilitate chemical recycling, reduce environmental pollution and are useful in implant immolation, drug delivery or as adhesives that debond on demand. However, polymers made by radical polymerization, which feature all carbon-bond backbones and constitute the most important class of polymers, have proven difficult to render degradable. Here we report cyclobutene-based monomers that can be co-polymerized with conventional monomers and impart the resulting polymers with mechanically triggered degradability. The cyclobutene residues act as mechanophores and can undergo a mechanically triggered ring-opening reaction, which causes a rearrangement that renders the polymer chains cleavable by hydrolysis under basic conditions. These cyclobutene-based monomers are broadly applicable in free radical and controlled radical polymerizations, introduce functional groups into the backbone of polymers and allow the mechanically gated degradation of high-molecular-weight materials or cross-linked polymer networks into low-molecular-weight species.

Hybrid Photoiniferter and Ring-Opening Polymerization Yields One-Pot Anisotropic Nanorods.

Polymerization-induced self-assembly (PISA) has emerged as a scalable one-pot technique to prepare block copolymer (BCP) nanoparticles. Recently, a PISA process, that results in poly(l-lactide)-b-poly(ethylene glycol) BCP nanoparticles coined ring-opening polymerization (ROP)-induced crystallization-driven self-assembly (ROPI-CDSA), was developed. The resulting nanorods demonstrate a strong propensity for aggregation, resulting in the formation of 2D sheets and 3D networks. This article reports the synthesis of poly(N,N-dimethyl acrylamide)-b-poly(l)-lactide BCP nanoparticles by ROPI-CDSA, utilizing a two-step, one-pot approach. A dual-functionalized photoiniferter is first used for controlled radical polymerization of the acrylamido-based monomer, and the resulting polymer serves as a macroinitiator for organocatalyzed ROP to form the solvophobic polyester block. The resulting nanorods are highly stable and display anisotropy at higher molecular weights (>12k Da) and concentrations (>20% solids) than the previous report. This development expands the chemical scope of ROPI-CDSA BCPs and provides readily accessible nanorods made with biocompatible materials.

Ternary nanocomposite of RAFT‐polymerized DMAEMA‐functionalized graphene oxide, manganese dioxide and polyaniline as active electrode material for supercapacitor

AbstractGraphene and its derivatives are promising energy storage devices due to their high specific surface area, chemical and thermal durability and high charge transfer power. Still, their stacking and aggregate behavior can limit their practical application. To address this issue, reversible addition–fragmentation chain‐transfer (RAFT) polymerization as controlled radical polymerization was applied to functionalize the surface of graphene oxide with poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) via the ‘grafting from’ method. This strategy enhances the distance between graphene sheets by occupying physical volume while improving effective charge transfer through tertiary amine groups participating in the doping process. X‐ray diffraction was used to determine interlayer spacing after polymer grafting, which increased from 0.28 to 1.71 nm after polymer grafting. The hybridization of materials with diverse properties was used to enhance charge transfer capability for supercapacitor applications. PDMAEMA‐functionalized graphene oxide, nano‐manganese dioxide and polyaniline were combined to create a successful nanocomposite as electrode active material. The morphological structure and chemical composition of the synthesized nanocomposite were analyzed, and its electrochemical performance was evaluated using cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The nanocomposite exhibited a maximum specific capacitance, energy density and power density of 364.72 F g−1 (at a scan rate of 50 mV s−1), 239.08 Wh kg−1 and 678.34 W kg−1, respectively. The final nanocomposite's energy storage capacity significantly increased compared to the individual components due to hybridization's synergistic impact, reducing charge transfer resistance. © 2024 Society of Industrial Chemistry.

Salts of Organic Acids as Reducing Agents in Atom Transfer Controlled Radical Polymerization

Salts of Organic Acids as Reducing Agents in Atom Transfer Controlled Radical Polymerization

Nitroxide-Mediated Controlled Radical Copolymerization of α-Trifluoromethylstyrenes with Styrenes.

Fluorinated polymers are important materials in everyday life; however, most monomers of widely used fluoropolymers are gaseous, and their polymerization is difficult in an ordinary laboratory. Therefore, partially fluorinated polymers have recently been reported. As an easy-to-handle fluorine-containing monomer, α-trifluoromethylstyrene (TFMST) can be used to produce partially fluorinated polymers with trifluoromethyl groups in the main chain; however, TFMST does not homopolymerize, and there are limited reports on its copolymerization with styrene (ST). In this study, we applied the controlled radical polymerization method, which is effective for the polymerization of ST, to the copolymerization of TFMST and ST. We also showed that nitroxide-mediated polymerization is effective. The content ratio of TFMST in the TFMST-ST copolymer can be controlled between 10% and 40% by changing its monomer ratio. Additionally, the polymerization of TFMST and ST with substituents was performed to increase structural variations. The thermal stability as well as water and oil repellency of the synthesized polymers with different composition ratios and substituents were also evaluated.

Postpolymerization Modification of Poly(2-vinyl-4,4-dimethyl azlactone) as a Versatile Strategy for Drug Conjugation and Stimuli-Responsive Release.

Postpolymerization modification of highly defined "scaffold" polymers is a promising approach for overcoming the existing limitations of controlled radical polymerization such as batch-to-batch inconsistencies, accessibility to different monomers, and compatibility with harsh synthesis conditions. Using multiple physicochemical characterization techniques, we demonstrate that poly(2-vinyl-4,4-dimethyl azlactone) (PVDMA) scaffolds can be efficiently modified with a coumarin derivative, doxorubicin, and camptothecin small molecule drugs. Subsequently, we show that coumarin-modified PVDMA has a high cellular biocompatibility and that coumarin derivatives are liberated from the polymer in the intracellular environment for cytosolic accumulation. In addition, we report the pharmacokinetics, biodistribution, and antitumor efficacy of a PVDMA-based polymer for the first time, demonstrating unique accumulation patterns based on the administration route (i.e., intravenous vs oral), efficient tumor uptake, and tumor growth inhibition in 4T1 orthotopic triple negative breast cancer (TNBC) xenografts. This work establishes the utility of PVDMA as a versatile chemical platform for producing polymer-drug conjugates with a tunable, stimuli-responsive delivery.

Surface Functionalization with Polymer Brushes via Surface-Initiated Atom Transfer Radical Polymerization: Synthesis, Applications, and Current Challenges.

Polymer brushes have received great attention in recent years due to their distinctive properties and wide range of applications. The synthesis of polymer brushes typically employs surface-initiated atom transfer radical polymerization (SI-ATRP) techniques. To realize the control of the polymerization process in different environments, various SI-ATRP techniques triggered by different stimuli have been developed. This review focuses on the latest developments in different stimuli-triggered SI-ATRP methods, such as electrochemically mediated, photoinduced, enzyme-assisted, mechanically controlled, and organocatalyzed ATRP. Additionally, SI-ATRP technology triggered by a combination of multiple stimuli sources is also discussed. Furthermore, the applications of polymer brushes in lubrication, biological applications, antifouling, and catalysis are also systematically summarized and discussed. Despite the advancements in the synthesis of various types of 1D, 2D, and 3D polymer brushes via controlled radical polymerization, contemporary challenges remain in the quest for more efficient and straightforward synthetic protocols that allow for precise control over the composition, structure, and functionality of polymer brushes. We anticipate the readers could promote the understanding of surface functionalization based on ATRP-mediated polymer brushes and envision future directions for their application in surface coating technologies.

Controlled Polymer Synthesis Toward Green Chemistry: Deep Insights into Atom Transfer Radical Polymerization in Biobased Substitutes for Polar Aprotic Solvents.

Cyrene (dihydrolevoglucosenone) and its derivative Cygnet 0.0, recognized as eco-friendly alternatives to polar aprotic solvents, were utilized in atom transfer radical polymerization (ATRP) of a wide range of both hydrophobic and hydrophilic (meth)acrylates. The detailed kinetics study and electrochemical experiments of the catalytic complex in these solvents reveal the opportunities and limitations of their use in controlled radical polymerization. Both solvents produce precisely controlled polymers using supplemental activator and reducing agent (SARA) ATRP. They offer an efficient reaction medium for crafting well-defined branched architectures from naturally derived cores such as riboflavin, β-cyclodextrin, and troxerutin, thereby significantly expanding the application scope of these solvents. Notably, Cygnet 0.0 significantly reduces side reactions between the solvent and the catalyst compared to Cyrene, allowing the catalyst complex to be used at a reduced concentration down to 75 ppm. The effective mass yield values achieved in Cyrene and Cygnet 0.0 underscore a substantial advantage of these solvents over DMF in generating processes that adhere to the principles of green chemistry. Furthermore, the copper residue in the final polymers was several hundred times lower than the permissible daily exposure to orally administered copper in pharmaceuticals. As a result, the resulting polymeric materials hold immense potential for various applications, including the pharmaceutical industry.

Antimony-Based Halide Perovskite Nanoparticles as Lead-Free Photocatalysts for Controlled Radical Polymerization.

Metal halide perovskites have emerged as versatile photocatalysts to convert solar energy for chemical processes. Perovskite photocatalyzed polymerization draws special attention due to its straightforward synthesis process and the ability to create advanced perovskite-polymer nanocomposites. Herein, this work employs Cs3Sb2Br9 perovskite nanoparticles (NPs) as a lead-free photocatalyst for light-controlled atom transfer radical polymerization (ATRP). Cs3Sb2Br9 NPs exhibit high reduction potential and interact with electronegative bromide initiator with Lewis acid Sb sites, enabling efficient photoinduced reduction of initiators and controlled polymerization under blue light irradiation. Methacrylate monomers with various functional groups are successfully polymerized, and the resulting polymer showcased a dispersity (Đ) as small as 1.27. The living nature of polymerization is confirmed by high chain end fidelity and kinetic studies. Moreover, Cs3Sb2Br9 NPs serve as heterogeneous photocatalysts, demonstrating recyclability and reusability for up to four cycles. This work presents a promising approach to overcome the limitations of lead-based perovskites in photoinduced controlled radical polymerization, offering a sustainable and efficient alternative for the synthesis of well-defined polymeric materials.

Highly hydrophilic methacrylamide-based copolymers as precursors for polymeric nanomedicines containing anthracyclines

The crucial limitation of most low molecular weight cytostatic drugs, including anthracyclines, is their nonspecific biodistribution causing severe adverse effects during cancer treatment. Recently, nanomedicines such as polymer-based systems have been developed as advanced drug delivery systems. Herein, we report the design, synthesis, and characterization of highly water-soluble polymer-carriers based on N‑(1,3‑dihydroxyprop-2-yl)methacrylamide (DHPMA). Polymers differing in molecular weight, hydrodynamic size, and dispersity were synthesized via free or controlled radical polymerization and conjugated to an anthracycline drug pirarubicin (THP) via a pH-sensitive hydrazone bond achieving up to 21 wt% of THP. The DHPMA copolymers were extensively compared to the well-known drug delivery vectors, N-(2-hydroxypropyl)methacrylamide (HPMA)-based copolymers. Importantly, DHPMA-based conjugates showed excellent hydrophilicity exceeding that of HPMA-based copolymers and did not aggregate even after loading with THP reaching 21 wt%. The DHPMA-based polymer nanomedicines exhibited excellent cytotoxicity, body biodistribution, tumor accumulation, and antitumor efficacy, significantly reducing the side effects and toxicity comparable to HPMA-based systems, thus demonstrating their applicability and suitability as efficient drug carriers.

Acid-triggered radical polymerization of vinyl monomers

Reversible addition–fragmentation chain-transfer (RAFT) polymerization is one of the most versatile and robust controlled radical polymerization methods owing to its broad material scope and high tolerance to various functionalities and impurities. However, to operate RAFT polymerization, a constant supply of radicals is required, typically via exogenous thermal radical initiators that are not only challenging to transport and store, but also primarily responsible for termination and end-group heterogeneity. Here we present an acid-triggered RAFT polymerization that operates in the dark and without any conventional radical initiator. Abundant acids (for example, sulfuric acid) are shown to have a dual role initiating and accelerating the polymerization. The polymers prepared have low dispersity and high end-group fidelity. The method is compatible with a wide range of vinyl monomers and solvents, and can be applied to the synthesis of well-controlled high molecular weight block copolymers, as well as to free radical polymerization.

Expanding the poly(2-oxazoline) block copolymer possibilities through nitroxide mediated polymerisation

In recent years, poly(2-oxazoline)s (POx) have become a sought-after biomaterial to replace PEG. However, access to POx based block copolymers is rather limited and their combination with controlled radical polymerization...

Shake, shear, and grind! - the evolution of mechanoredox polymerization methodology.

In the last half decade, mechanoredox catalysis has enabled an entirely new genre of polymerization methodology. In this paradigm, mechanical force, such as ultrasonic cavitation bubble collapse or ball mill grinding, polarizes piezoelectric nanoparticles; the resultant piezopotential drives the redox processes necessary for free- and controlled-radical polymerizations. Since being introduced, evolution of these methods facilitates exploration of mechanistic underpinnings behind key electron-transfer events. Mechanical force has not only been identified as a "greener" alternative to more traditional reaction stimuli (e.g., heat, light) for the synthesis of commodity polymers, but also a potential technology to enable the production of novel thermoplastic and thermoset materials that are either challenging, or even impossible, to access using conventional solution-state approaches. In this Feature Article, significant contributions to such methods are highlighted within. Advances and ongoing challenges in both ultrasound and ball milling driven reactions for radical polymerization and crosslinking are identified and discussed.

CuBr-mediated surface-initiated controlled radical polymerization in air

Herein, we present a straightforward CuBr-mediated surface-initiated controlled radical polymerization (SI-CRP) method for fabricating polymer brushes using microliter volumes of reaction solution in air and at room temperature. The key...

Thiol-selective native grafting from polymerization for the generation of protein-polymer conjugates.

Protein-polymer conjugates combine properties of biopolymers and synthetic polymers, such as specific bioactivity and increased stability, with great benefits for various applications from catalysis to biomedicine. Furthermore, polymer conjugation can mimic important posttranslational modifications of proteins such as glycosylation. There are typically two approaches to create protein-polymer conjugates: the protein is functionalized in advance with an initiator for a grafting-from method or a previously produced polymer is conjugated to the protein via a grafting-to method. In this study, we present a new approach that uses native proteins and allows for direct grafting-from using a thiol-induced, light-activated controlled radical polymerization (TIRP) that is initiated at thiols from specific cysteine residues of the protein. This straightforward method is employed to introduce polymers onto proteins and enzymes without any prior protein modifications, it works in aqueous buffer and maintains the protein's native structure and activity. The resulting protein-polymer conjugates exhibit high molar masses and low dispersities. We demonstrate the versatility of this approach by introducing different types of polymers such as hydrophilic poly(2-hydroxyethyl acrylate) (pHEAA), temperature-responsive poly(N-isopropylacrylamide) (pNIPAM) as well as glycopolymers mimicking the natural protein glycosylation and enabling selective interactions. We present successful combinations of the protein and polymer functions e.g., temperature-induced aggregation leading to an increase in enzyme activity and the introduction of artificial glycosylation inducing specific protein-protein cluster formation and giving straightforward access to glycosurfaces. Based on this straightforward, potentially scalable yet highly controlled synthesis of protein-polymer conjugates, various areas of applications are envisioned ranging from biomedicine to material sciences.

Chemical recycling of bromine-terminated polymers synthesized by ATRP.

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.

Exploration of lignin-binding synthetic polymers with pendant hydrophobic amino acids

Polymers bearing amino acid methyl esters with a terminus fluorescein group were synthesized through controlled radical polymerization employing a fluorescein-labeled chain transfer agent and subsequent postpolymeization modification with amino acid...

SYNTHESIS OF COPOLYMERS OF STEARYLMETHACRYLATE AND STEARYLACRYLATE WITH N-SUBSTITUTED ACRYLAMIDES IN THE PRESENCE OF REVERSIBLE CHAIN TRANSFER AGENTS AND STUDY OF THEIR EFFECT ON THE LOW-TEMPERATURE PROPERTIES OF DIESEL FUEL

The features of copolymerization of stearylacrylate (SA) and stearylmethacrylate with N-isopropylacrylamide and N,N-dimethylacrylamide in the presence of dibenzyltrithiocarbonate and 2-cyanoisopropyldodecyltrithiocarbonate as agents of reversible chain transfer have been studied. The choice of agents of reversible chain transfer (RAFT-agents) is due to the fact that sulfur-containing compounds with cyanoisopropyl radicals are most effective in the polymerization of methacrylic monomers, while benzyltrithiocarbonates are more active in the polymerization of acrylic monomers, as well as styrene and acrylonitrile. It has been established that polymerization of stearyl methacrylate (SMA) in the presence of RAFT-agents proceeds without a gel effect up to a high conversion. At the same time, although polystеarylmethacrylate samples are characterized by relatively high values of polydispersity coefficients (Mn/Mw) for controlled radical polymerization processes, they are nevertheless somewhat lower than for polymers of similar conversion synthesized in the absence of chain transfer agents. It has been shown that the process of copolymerization of stearyl acrylate and stearylmethacrylate with N-isopropylacrylamide and N,N-dimethylacrylamide in the presence of dibenzyltrithiocarbonate and 2-cyanoisopropyldodecyltrithiocarbonate proceeds without gelation to high conversions. The synthesized copolymers are characterized by a relatively narrow molecular weight distribution: the polydispersity coefficients of polymer samples vary from 1.18 to 1.57 in the case of using N-isopropylacrylamide and from 1.21 to 1.47 when using N,N-dimethylacrylamide as a comonomer to higher alkyl acrylates, which is typical for processes of radical polymerization proceeding in a controlled manner. At the same time, the synthesized copolymers exhibit a significant depressant effect when they are introduced into diesel fuel at a concentration of 1600 ppm. It has been established that copolymers of stearylmethacrylate and stearylacrylate with polar nitrogen-containing monomers have a more effective effect on the low-temperature properties of diesel fuel than homopolymers of stearylmethacrylate and stearylacrylate. At the same time, additives based on copolymers of stearylmethacrylate with N-isopropylacrylamide with a composition of 70/30 mol.% and stearylacrylate with N-isopropylacrylamide with a composition of 20/80 mol.% had the most significant effect on the low-temperature characteristics of the fuel.