ATRP Polymerization Research Articles

Designing Ionic Ir(III) Cyclometalated Complexes as Photocatalysts for Light Assisted ATRP of MMA. A Combined Experimental and Mechanistic Study.

A new family of ionic Ir(III) cyclometalated complexes with general formula [Ir(CN)2(NN)][Br], was designed and prepared to be assessed as photocalysts for the visible light assisted ATRP polymerization of MMA. To this purpose, our design strategy involved both: i) the decoration of the cyclometalating (CN) and the ancillary (NN) ligands with various electron withdrawing and/or electron donor substituents and, ii) the use of Br- as the counter anion for these cationic Ir(III) species. After an extensive screening in which the [Ir(CN)2(NN)][Br]-type compounds were compared to the model neutral complex fac-[Ir(ppy)3], the "fully" amino-substituted ion pairs abbreviated as [10][Br] and [11][Br], exhibited the best photocatalytic performances under irradiation with CFL lamps. It is worth noting that the outcomes of transient absorption spectroscopy (TAS) experiments combined with theoretical DFT calculations, enlightened the role played by the Ir(III) complexes in the mechanism of the photoATRP process, and suggested the rationalization of the different performances that were highlighted by our Ir(III) catalyst in the visible light assisted photopolymerization of MMA.

Sulfur-doped anthanthrenes as effective organic photocatalysts for metal-free ATRP and PET-RAFT polymerization under blue and green light

A new family of photoredox catalysts, sulfur-doped anthanthrenes (SDAs), have been successfully developed for metal-free O-ATRP and PET-RAFT polymerization under visible light and even green light.

Suspension Photopolymerization of Methyl Methacrylate and ATRP Grafting of Thermo‐Responsive Polymers Using a Perylediimide Derivative Photoinitiator

AbstractThe first aim of this study is to develop a photo‐ATRP process using methyl methacrylate (MMA) by employing a novel perylenediimide derivative (PDI) as photoinitiator. The analysis of the MMA photopolymerization process kinetics is performed in solution and in bulk, demonstrating control over the reaction progress even if the polymerizations display a slow initiation step. The photo‐ATRP process for MMA in suspension is also developed and the obtained PMMA particles are further used to reinitiate the ATRP polymerization of thermoresponsive polymers (different molecular weights poly(ethylene glycol) methyl ether methacrylate and poly(N‐isopropylacrylamide)) (PNIPAM) in solution and surface‐initiated processes. The synthesized polymers by surface‐initiated process display a bimodal molecular weight distribution with a clear modification of the signal areas ratio depending on the grafted monomer and on the reaction conditions. The grafting process can take place on the surface of the polymer particles (Mn2), or it can also involve polymer chains located further at the interior of the polymer particles (Mn1). The lower critical solution temperature (LCST) transition is demonstrated for the PNIPAM functionalized polymer particles.

Solvent‐Free Chemical Recycling of Polymethacrylates made by ATRP and RAFT polymerization: High‐Yielding Depolymerization at Low Temperatures

AbstractAlthough 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.

Solvent-Free Chemical Recycling of Polymethacrylates made by ATRP and RAFT Polymerization: High-Yielding Depolymerization at Low Temperatures.

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.

Antibacterial polymeric micelles based on kojic acid/acrylic acid/chitosan

In the present study, antibacterial micelles based on poly [5-(benzyloxy)-4-oxo-4H-pyran-2-yl] methyl acrylate/polyacrylic acid/chitosan(PBOPMA-PAA-Cs) terpolymer with suspended kojic acid groups was synthesized. For this purpose, first, protected kojic acid (BOP) was prepared by reaction of 5-hydroxy-2-hydroxymethyl-4 H-pyran-4-one with benzyl chloride. Subsequently, [5-(benzyloxy)-4-oxo-4H-pyran-2-yl] methyl acrylate(BOPMA) was prepared by esterification reaction between protected kojic acid hydroxyl groups and carboxylic groups related to acrylic acid. The initiator, [5-(benzyloxy)-4-oxo-4H-pyran-2-yl] methyl-2-bromo-2-methylpropanoate (BOPBr), was synthesized via acyl nucleophilic substitution. Polymerization of BOPMA by ATRP polymerization using initiator (BOPBr) was performed. The PBOPMA-PAA copolymer was prepared by free radical polymerization. In the final step, PBOPMA-PAA-Cs terpolymer was prepared by esterification reaction of the N-phthaloylated chitosan hydroxyl group with the carboxylic acid groups of the PBOPMA-PAA copolymer. Micelles with a size of 20 ± 5 nm were prepared from amphiphilic terpolymers and their morphology and size were evaluated by TEM and DLS, respectively. The structure, thermal stability, and morphology of synthesized compounds were confirmed by FT-IR, 1H-NMR, TGA, and SEM. Furthermore, in the study of antibacterial properties against gram-positive and negative bacteria, PBPMA, PBPMA-PAA, and PBPMA-PAA-Cs behaved differently, however, all three had good antibacterial properties compared to gentamicin and ampicillin.

Hyperbranched PDMAEMA-functionalized SiO2 microparticles: ATRP polymerization and grafting in a continuous flow reactor

Hyperbranched PDMAEMA-functionalized SiO2 microparticles: ATRP polymerization and grafting in a continuous flow reactor

Fabrication of PVDF mixed matrix nanofiltration membranes incorporated with TiO2 nanoparticles and an amphiphilic PVDF‐g‐PMMA copolymer

AbstractIn this work, the ATRP polymerization technique was first utilized for controlled grafting of methyl methacrylate monomers from a Poly(vinylidene fluoride) (PVDF) backbone with a predefined molecular weight and narrow molecular weight distribution. After the successful formation of the copolymer, different amounts of the prepared PMMA‐g‐PVDF copolymer along with TiO2 nanoparticles were then employed for the fabrication of PVDF mixed matrix membranes (MMMs). The separation performance of the fabricated membranes was evaluated in rejection of different dyes including Methyl Green (MG), Rhodamine B (RDB), Crystal Violet (CV), and Methylene Blue (MB) from aqueous solutions. It was observed that a high rejection ability (99.6%, 99.1%, 98.9%, and 96.1% for MG, RDB, CV, and MB), a good permeate Flux of 8.35 L/m2 h along with an outstanding antifouling performance were provided by the membrane with 0.4% PVDF‐PMMA and 0.2%TiO2.

Kill two birds with one stone: Selective and fast removal and sensitive determination of oxytetracycline using surface molecularly imprinted polymer based on ionic liquid and ATRP polymerization

Oxytetracycline (OTC) residue in food and environment has potential threats to ecosystem and human health, thus its sensitive monitoring and effective elimination are very important. In this work, a new molecularly imprinted polymer (MIP) composite was prepared through atom transfer radical polymerization by using OTC as template, gold nanoparticles modified carbon nanospheres (Au-CNS) as supporter, ionic liquids (IL) as functional monomer and cross-linking agent. The obtained MIP-IL@Au-CNS composite was characterized by Fourier transform infrared absorption spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. It displayed high imprinting factor (5.50) and adsorption capacity (56.7 mg g−1), and could achieved the adsorption equilibrium in short time (about 15 min). Results also illustrated that the adsorption process basically conformed to the quasi-second-order kinetic model and Freundlich model, and MIP-IL@Au-CNS could be recycled at least 5 times. Furthermore, a sensitive OTC electrochemical sensor was developed by combining MIP-IL@Au-CNS with IL-modified carbon nanocomposites (IL@N-rGO-MWCNT). The resulting sensor demonstrated a linear response to OTC in the wide range of 0.02–20 μM, and the detection limit was down to 5 nM. It also had the advantages of high selectivity, fast elution/regeneration and simple construction procedure. The sensor had been applied to the detection of real samples, and acceptable recovery (96.4%−106%) and RSD (3.2%−6.2%) were obtained. This work expands the application of IL-based MIP in pollutant monitoring and enriching.

Organocatalytic orthogonal ATRP and ring-opening polymerization using a single dual-function photocatalyst

Organocatalytic orthogonal atom transfer radical polymerization and ring-opening polymerization have been achieved using a single designer dual-function photocatalyst.

Synergistic Stain Removal Achieved by Controlling the Fractions of Light and Thermo Responsive Components in the Dual-Responsive Copolymer Immobilized on Cotton Fabrics by Cross-Linker.

Enhanced synergistic stain removal is realized by tailoring the comonomer fractions of a light- and thermo-dual responsive copolymer, which is immobilized on cotton fabrics by a cross-linker. The copolymer poly(acrylamide azobenzene-co-ethylene glycol methacrylate-co-triethylene glycol methyl ether methacrylate), denoted P(AAAB1-co-EGMA2-co-MEO3MA17), is prepared by the ATRP polymerization method. The present molar ratio for these monomers is 1:2:17. Because of the existence of the light-responsive AAAB unit, the transition temperature of its aqueous solution under UV radiation is shifted to 39 °C, which is 2 °C higher than that in ambient conditions. This increase is caused by the trans-cis isomerization from the azobenzene groups, indicating an increased hydrophilicity of P(AAAB1-co-EGMA2-co-MEO3MA17) under UV radiation. After being immobilized onto cotton fabrics by a cross-linker, they are also dual-responsive. The equilibrium swelling ratio (ESR) of the cotton fabrics is further increased after UV radiation. Compared to our former investigation, the reduction of the AAAB molar fraction from 0.1 to 0.05 causes an increase of the ESR value by 10%. Moreover, the stain removal efficiency of the cotton fabrics immobilized with P(AAAB1-co-EGMA2-co-MEO3MA17) by cross-linker is also significantly improved under UV radiation. The hydrophilicity of the copolymer mainly from the MEO3MA units is crucial to the cleaning capability. Additionally lowering the attachment between stain and the copolymer coating on the cotton fabrics by trans-cis isomerization in those AAAB units also favors the cleaning. Hence, the stain removal is strongly improved by optimizing the fraction of light- versus thermo-responsive components in the copolymer, which can profoundly reduce the consumption of chemical detergents and energy during laundry.

Co-delivery of cisplatin and doxorubicin by carboxylic acid functionalized poly (hydroxyethyl methacrylate)/reduced graphene nanocomposite for combination chemotherapy of breast cancer cells

In this study a novel pH-responsive magnetic nanocomposite based on reduced graphene oxide was developed for combination of doxorubicin (Dox)-cisplatin (Cis) delivery to destroy the MCF-7 cell line. For this purpose, polyhydroxyethyl methacrylate (PHEMA) was bonded to the reduced graphene oxide through ATRP polymerization using grafting from method. Then the PHEMA hydroxy groups were converted to succinyloxy groups by polyesterification with succinic anhydride. The physicochemical properties of the nanocomposite were investigated via FTIR, SEM, XRD, DLS and TGA analysis. Unique structure of nanocomposite led to simultaneous encapsulation of Dox (75%) and Cis (82%) through ionic interaction, π–π stacking and hydrogen bonding. The obtained nanocomposite was uptake by MCF-7 cells at early first hour because of nanocomposite small size (below 70 nm). Cell viability assay results revealed that the Dox&Cis-loaded nanocomposite showed the highest rate of MCF-7 cells at lowest concentration (IC50 = 0.798 µg/mL) compared to treatment groups received single drug-loaded nanocomposite and free drugs. Dox&Cis-loaded nanocomposite exhibited a synergistic influence with the combination index (CI) value <1. The cell cycle analysis results revealed that the highest amount of apoptosis (cells population in sub G1 was 75%) was observed in the Dox&Cis-loaded nanocomposite treatment group compared with the single drug-loaded nanocomposite and free drugs. Our findings confirmed that combinational therapy by Dox and Cis graphene oxide-based nanocomposite has increased the cytotoxicity in MCF-7 cells by stimulating the apoptotic response.

ATRP Initiators Based on Proton Transfer Benzazole Dyes: Solid-State Photoactive Polymer with Very Large Stokes Shift

This work presents the synthesis, photophysical characterization, and application of ATRP polymerization initiators to produce photoactive solid-state fluorescent polystyrene-based polymers. These ...

Synthesis of temperature and light sensitive mixed polymer brushes via combination of surface-initiated PET–ATRP and interface-mediated RAFT polymerization for cell sheet application

In this study, a series of temperature and light sensitive mixed polymer brushes consisting of poly(2-(2-methoxyethoxy) ethyl methacrylate) [poly(MEO2MA)] and poly(N-[4-[(4-nitrophenyl) azo] phenyl] acrylamide) [poly(NPAPAA)] units were grown on silicon wafer via the combination of surface-initiated photoinduced electron transfer-atom transfer radical polymerization (PET-ATRP) and interface-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization. This process was realized in five consecutive steps: (i) coupling of previously synthesized (3-aminopropyl) triethoxysilane-2-bromoisobutyryl bromide (APTES-BIBB) and (3-aminopropyl) triethoxysilane-t-butoxycarbonyl (APTES-t-BOC) mixtures to the Si-OH surface under self-assembly monolayer conditions (ii) synthesis of poly(MEO2MA) units via surface-initiated PET-ATRP (iii) replacement of terminal-Br atoms at poly(MEO2MA) units with biocompatible maleimide molecules (iv) removal of the t-BOC group from APTES-t-BOC and bonding of the RAFT agent to the APTES, and (v) synthesis of poly(NPAPAA) units via the interface-mediated RAFT polymerization. The surface compositions of APTES-BIBB and APTES-t-BOC molecules were determined by the water contact angle data analyzed with the Israelachvili-Gee model and by the X-ray photoelectron spectroscopy measurements. The grafting density (σ, chains nm−2) and the average distance between grafting points (D, nm) of the mixed polymer brushes are about 0.56 chains nm−2 and 1.52 nm, respectively, indicating high grafting density. The lower critical solution temperatures (LCSTs), trans-cis and cis-trans transition times were in the range of 24.6–29.2 °C, 10–25 min and 8–20 min, respectively, depending on the surface composition of the polymer brushes. Cell culture studies revealed successful cell detachment either via the temperature reduction or UV irradiation methods. The cell recovery ratios were recorded as 99.05 ± 0.45% and 83.95% ± 0.58%, respectively. These experimental findings provided basic information at the molecular level in the preparation of temperature and light- sensitive bioactive surfaces for cell sheet preparation and detachment state.

Homogeneous polymerization of hydrophobic monomers in a bio-based dl-menthol/1-tetradecanol eutectic mixture by ATRP and RAFT polymerization

A bio-based eutectic mixture, composed of dl-menthol and 1-tetradecanol, was investigated for the first time as solvent for the homogeneous ATRP and RAFT polymerization of different hydrophobic monomers.

Polymers prepared through an "ATRP polymerization-esterification" strategy for dual temperature- and reduction-induced paclitaxel delivery.

Clinically, the nanotherapy of tumors has been limited by the drug content, efficiency of targeted release, and bioavailability. In this study, we fabricated an amphiphilic block polymer, poly(2-methacryloyloxyethyl thiocticcarboxylate)-block-poly(N-isopropylacrylamide) (PMAOETC-b-PNIPAM), using an “ATRP polymerization–esterification” strategy for paclitaxel (PTX) delivery. The hydrophobic drug paclitaxel was encapsulated based on hydrogen bond interactions between PTX and the PMAOETC and PNIPAM blocks, together with hydrophobic interactions between PTX and PMAOETC segments, affording PTX-laden polymer micelles with ∼30% drug loading content. The critical micelle concentration of the PTX-loaded polymeric micellar aggregates was 34.53 mg l−1, as determined through fluorescence spectroscopy, which indicated favorable stability during infinite dilution by body fluids. The phase transition temperature of the micelles was tunable (36.10–39.48 °C) via adjusting the lengths of the blocks. The PTX-laden micelles showed the release of a significant amount of PTX in cancerous tissue, while negligible cytotoxicity was shown against HCT-116 cells in PBS at pH 7.4 and 37 °C. Further in vivo anticancer studies revealed that antitumor treatment using the PTX-laden micelles caused a significant suppression in tumor volume compared with a free-PTX-treated group. This study provides a reference for improving drug content levels and optimizing the therapeutic effects of drug delivery systems from the perspective of polymer preparation.

Facile Construction of Microgel based Biomimetic Glutathione Peroxidase with Temperature Responsive Catalytic Activity

AbstractGlutathione peroxidase (GPx) is an important antioxidant enzyme. The exploration of a simple and efficient strategy for preparing biomimetic GPx is of great significance, because it can provide theoretical supports for the development of antioxidant drugs that can regulate the concentration of free radicals. In this work, a microgel based biomimetic GPx (PAMTegel) with temperature responsive catalytic activity was simply and efficiently constructed by the combination of one‐pot method and ATRP polymerization. The PAMTegel exhibited a typical enzymatic catalytic behavior with temperature responsiveness. The catalytic activity of PAMTegel could be facilely regulated by adjusting temperature from 25 to 50 °C. The hydrophobicity change of poly(N‐isopropylacrylamide) (PNIPAM) molecular chain in the PAMTegel was the key factor to manage the catalytic activity. The strategy for constructing temperature responsive biomimetic GPx and the related investigation for its catalytic mechanism may provide an important theoretical basis for the development of intelligent antioxidants.

Poly(ionic liquid)-Modified Magnetic Janus Particles for Dye Degradation.

The Fe3O4@SiO2 paramagnetic Janus particles with phenyl groups and amino groups segmented on two different sides were fabricated by the Pickering emulsion method. Then, the poly(ionic liquid)s were selectively modified onto the amino side via in situ induced ATRP polymerization. Different anions were introduced onto the poly(ionic liquid)s region by exchanging anions to adjust the wettability of the side. Meanwhile, after the PW12O403- anions were employed, the poly(ionic liquid)-modified Fe3O4@SiO2 Janus particles can be used as a catalytic solid emulsifier and degraded water-soluble dyes with the aid of stabilizing emulsion.

Synthesis of homo/3‐ and 4‐armed hydrophilic glycopolymers: To promote aniline to polyaniline‐glycopolymers for fluorescence, electro active material, and electrostatic discharge applications

ABSTRACTPreparation of electrically conducting polymer film with homogeneity is very important work for electrical and electronic applications. In order to make homogenous conductive polyaniline film, we selected water soluble glycopolymer (GP), as dopant for polyaniline. Pendant carbohydrates water soluble glycopolymer architectures, such as, homo, 3 and 4 multi‐armed polymers were prepared from methacryl‐2,3,4,6‐tetra‐O‐acetyl‐D‐glucopyranoside (MTAGP) monomer and EBrIB and 3‐ and 4‐aremed initiators via ATRP polymerization followed by deacetylation process. This water soluble glycopolymer was used as dopant for polyaniline salt via the chemical oxidative emulsion polymerization of aniline using glycopolymer and surfactant by ammonium persulfate oxidant. Sulfate and dodecylhydrogen sulfate (DHS) groups are doped on polyaniline system via protonating H+, whereas, glycopolymer involves on polyaniline through hydrogen bonding (PANI‐DHS‐SA‐GP). Coated film of PANI‐DHS‐SA‐GP salt showed resistance in ESD range. PANI‐DHS‐SA‐GP showed fluorescence and Hydrophilicity. Electrochemical performance of PANI‐DHS‐SA‐GP as electrode material in supercapacitor cell was found from charge–discharge measurement. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48043.

Effect of solvents on the RAFT polymerization of N-(2-hydroxypropyl) methacrylamide

Poly(N-(2-hydroxypropyl) methacrylamide) (PHPMA) is a promising drug platform as it is non-immunogenic, biocompatible and hydrophilic polymer. It is the first copolymer-drug conjugates to be evaluated in clinical trials. However, it is challenging to obtain well-controlled PHPMA with high conversions via either ATRP or RAFT polymerization in most organic solvents. In this study, we systematically investigate the polymerization of HPMA via RAFT in various solvents using 4-cyano-4-(((ethylthio)thioxomethyl)thio)pentanoic acid as a chain transfer agent. Kinetic experiments demonstrated that the retardation was alleviated in aprotic solvents resulting in low conversions and poor controllability of the polymerization. Variable temperature analyses and molecular dynamic simulation proved the low conversion and poor control of PHPMA was attributed to the hydrogen bonding of the polymeric system and the theoretical results are consistent with our experimental observations.