Mediated Reversible-deactivation Radical Polymerization Research Articles

Cytotoxicity and Bioimmunological Activity of Poly(2-Isopropenyl-2-oxazoline) Conjugates with Ibuprofen Using 3D Reconstructed Tissue Models.

Poly(2-isopropenyl-2-oxazoline) (PIPOx) represents a universal polymer platform with pendant 2-oxazoline groups, allowing the preparation of biomaterials for various biomedical applications. However, there is a lack of information on PIPOx concerning the effect of molar mass (Mn) on cytotoxicity and bioimmunological properties. Here, aqueous copper(0)-mediated reversible-deactivation radical polymerization (Cu0-RDPR) was used for the preparation of PIPOx with defined Mn and low dispersity. PIPOx of different Mn are used for the synthesis of conjugates with ibuprofen (5 mol %), the nonsteroidal anti-inflammatory drug. The release of ibuprofen at 37 °C and different pH values is monitored using high-performance liquid chromatography, where the rate of drug release increases with increasing pH and lower Mn. In vitro cytotoxicity and bioimmunological properties of PIPOx and drug conjugates are studied using 3D reconstructed tissue models of the human epidermis and intestinal epithelium. We demonstrate low cytotoxicity of PIPOx and conjugates with different Mn values on both 3D tissue models.

Precise Synthesis of Tetrablock Copolymers of Different Acrylamide Derivatives via Iterative Aqueous Cu(0)-Mediated Polymerization

The accessibility of specific synthesis of tetrablock copolymers is reported. In a specific synthesis, four acrylamide monomers are gradually added using an iterative aqueous Cu(0)-mediated reversible-deactivation radical polymerization (RDRP) method. Essential to the success of this approach is the ability to design and polymerize ABCD copolymer sequence with no need for immediate purification steps. The simple in-situ sequential polymerization method allowed for essentially perfect control of accurately well-defined tetrablock copolymers, which are composed of four tiny blocks, each of which contains an average of ten functional monomer units of acrylamide derivatives, resulting in a variety of functional groups. While the final molecular weight distributions have very narrow despersities (Đ < 1.10), the efficient successive chain extension polymerization proceeded with high monomer conversions (>99%), delivering excellent block purification in a short period of time. The tetrablock poly(NIPAM-DMA-HEAA-DEA) was characterized by NMR and GPC and showed beneficial end-group fidelity, allowing quantitative monitoring of the system’s alive nature after each synthetic cycle. Importantly, these one-pot syntheses are carried out at a below temperature of 0.0 °C in water as the solvent and can be implemented for applications of molecular biology. We also investigate the potential for a copper-amide complex to develop with acrylamide monomer, which could have an adverse effect on the end group’s functioning. Finally, we believe that this approach makes it easier to create a novel category of advanced polymeric materials.

One-pot and One-step Cu(0)-mediated Reversible-Deactivation Radical Polymerization of N-Isopropylacrylamide (NIPAM) in Water

One-pot and One-step Cu(0)-mediated Reversible-Deactivation Radical Polymerization of N-Isopropylacrylamide (NIPAM) in Water

Controlled Polymerization of Acrylamide via One-Pot and One-Step Aqueous Cu(0)-Mediated Reversible-Deactivation Radical Polymerization.

Copper-catalyzed controlled polymerization of acrylamide (AM) has always been a challenge, which typically exhibits low monomer conversion and broad molecular weight distribution (MWD) or requires complex/multistep reaction procedures, due to the highly active nature of the AM radical and its side reactions. To overcome the above challenges, herein, we report the successful synthesis of well-defined polyacrylamide (PAM) via a facile one-pot and one-step aqueous Cu(0)-mediated reversible-deactivation radical polymerization (RDRP). The results of this strategy show that strong deactivation control is the key for the controllability of AM RDRPs, which depends on the equilibria of polymerization and mutual conversion of different copper species. With the fast-propagating monomer AM, extra addition of CuII into the reaction system is an effective way to enhance deactivation. Based on this kinetically controlled strategy, well-defined PAMs with narrow molecular weight distributions (MWDs) and varied molecular weights (Mws) were successfully achieved.

Ultrasound-assisted dispersive magnetic solid-phase extraction of cadmium, lead and copper ions from water and fruit juice samples using DABCO-based poly (ionic liquid) functionalized magnetic nanoparticles

A poly (ionic liquid) (PIL) functionalized magnetic nanoparticles methodology was developed and utilized as an efficient adsorbent for the simultaneous extraction of cadmium, lead, and copper ions from water and fruit juice samples. The novel adsorbent was fabricated by grafting DABCO-based PIL onto silica-coated Fe3O4 nanoparticles via copper (0)-mediated reversible-deactivation radical polymerization. Different techniques properly characterized the developed nanoparticles. The central composite design was used to analyze the simultaneous effects of various parameters on the extraction efficiency. The detection limits for water samples ranged between 3.2 and 9.2 ng.L-1, and fruit juice samples varied from 0.0103 to 0.1082 μg.kg−1. The recovery ranged from 94.1 to 101.3% and 93.6 to 105.1% for water and fruit juice samples, respectively. The relive measurement uncertainty ranged from 7.7 to 13.6%. The proposed method is rapid, sensitive, environmentally friendly, and useful for monitoring the residues of heavy metal ions in water and fruit juice samples.

Brush-like Polymer Prodrug with Aggregation-Induced Emission Features for Precise Intracellular Drug Tracking.

In this study, a brush-like polymer with aggregation-induced emission (AIE) features was synthesized for drug delivery and intracellular drug tracking. The polymer consisting of tetraphenylethene (TPE) chain-end as well as oligo-poly (ethylene glycol) (PEG) and hydrazine functionalities was successfully synthesized through copper (0)-mediated reversible-deactivation radical polymerization (Cu0-mediated RDRP). Anticancer drug doxorubicin (DOX) was conjugated to the polymer and formed a prodrug named TPE-PEGA-Hyd-DOX, which contains 11% DOX. The hydrazone between DOX and polymer backbone is a pH-sensitive linkage that can control the release of DOX in slightly acidic conditions, which can precisely control the DOX release rate. The drug release of 10% after 96 h in normal cell environments compared with about 40% after 24 h in cancer cell environments confirmed the influence of the hydrazone bond. The ratiometric design of fluorescent intensities with peaks at 410 nm (emission due to AIE feature of TPE) and 600 nm (emission due to ACQ feature of DOX) provides an excellent opportunity for this product as a precise intracellular drug tracker. Cancer cells confocal microscopy showed negligible DOX solution uptake, but an intense green emission originated from prodrug uptake. Moreover, a severe red emission in the DOX channel confirmed a promising level of drug release from the prodrug in the cytoplasm. The merged images of cancer cells confirmed the high performance of the TPE-PEGA-Hyd-DOX compound in the viewpoints of cellular uptake and drug release. This polymer prodrug successfully demonstrates low cytotoxicity in healthy cells and high performance in killing cancer cells.

Self-Assembled Multi- and Single-Chain Glyconanoparticles and Their Lectin Recognition.

In this work, we describe the physicochemical characterization of amphiphilic glycopolymers synthesized via copper(0)-mediated reversible-deactivation radical polymerization (Cu-RDRP). Depending on the chemical composition of the polymer, these glycopolymers are able to form multi-chain or single-chain polymeric nanoparticles. The folding of these polymers is first of all driven by the amphiphilicity of the glycopolymers and furthermore by the supramolecular formation of helical supramolecular stacks of benzene-1,3,5-tricarboxamides (BTAs) stabilized by threefold hydrogen bonding. The obtained polymeric nanoparticles were subsequently evaluated for their lectin-binding affinity toward a series of mannose- and galactose-binding lectins via surface plasmon resonance. We found that addition of 2-ethylhexyl acrylate to the polymer composition results in compact particles, which translates to a reduction in binding affinity, whereas with the addition of BTAs, the relation between the nature of the particle and the binding ability system becomes more unpredictable.

Thermal responsive poly(N-isopropylacrylamide) grafted chicken feather keratin prepared via surface initiated aqueous Cu(0)-mediated RDRP: Synthesis and properties

Poultry chicken feather keratin was extracted and then modified for the fabrication of keratin-graft-PNIPAM copolymers. The keratin was well extracted from feather fiber and powdered. Subsequently, it underwent the surficial functionalization process with initiator groups. After the study conducted full disproportionation of Cu(I)Br/Me6Tren into Cu(0) and Cu(II)Br2 in the solvent, surface initiated aqueous Cu(0)-mediated reversible-deactivation radical polymerization (RDRP) of N-isopropylacrylamide (NIPAM) was performed in a methanol/water mixture solvent. The reaction was performed rapidly and efficiently, during which over 100% graft rate was achieved at 60 min. After 6 h reaction, 200% graft rate could be achieved. High graft rate (up to 287%) was achieved, and graft rate could be regulated by controlling the reaction time and the addition of monomer. The fabricated keratin-g-PNIPAM exhibited a rough surface. As revealed from the results of thermal analysis, the thermal stability of keratin-g-PNIPAM was enhanced noticeably compared with the original keratin. Besides, grafted PNIPAM chains exhibited a higher glass transition temperature. The grafted keratin particles displayed enhanced hydrophilicity. Keratin-g-PNIPAMs exhibit a lower LCST comparing to homopolymer and the flocculation in hot water behavior could be controlled by regulating graft rate.

Rapid removal of anionic dye from water by poly(ionic liquid)-modified magnetic nanoparticles

A poly(ionic liquid) (PIL) functionalized magnetic responsive nanocomposite was developed and utilized as a highly efficient sorbent for dyes removal. The adsorbent was prepared by grafting PIL onto silicon coated Fe3O4 nanoparticles via Cu(0)-mediated reversible-deactivation radical polymerization (RDRP) method. The obtained Fe3O4@SiO2@PIL nanocomposite was characterized by various techniques, and tested for removal of different ionic dyes, including alizarin red (AR), thionin acetate (TA), malachite green (MG) and acid orange II (AO). The adsorbent showed ultrafast adsorption and large adsorption capacity by reaching a maximum adsorption amount of AR up to 510.2 mg·g−1. Furthermore, the sorbent was capable to selectively adsorb the anionic dyes from aqueous solutions of mixed dyes. In addition, influences of some important factors upon the adsorption process were investigated, including adsorption temperature and time, pH value and initial dye concentration. The magnetic nanoparticles could be readily collected by applying a magnetic field and regenerate with a salt solution. The results demonstrate that the Fe3O4@SiO2@PIL nanocomposite has great potential as an efficient, functional and durable sorbent for water treatment.

Crosslinked pH-responsive polymersome via Diels-Alder click chemistry: A reversible pH-dependent vesicular nanosystem

Herein, we have developed pH-responsive shape-persistent polymersomes made of well-defined amphiphilic poly(ethylene oxide)-block-poly(diisopropylaminoethyl methacrylate-co-furfuryl methacrylate)s PEO-b-P(DPA-co-FMA) by exploiting Diels-Alder chemistry as a robust and simple crosslinking method. Using Photo-induced Copper Mediated Reversible Deactivation Radical Polymerization, we synthesized PEO-b-P(DPA-co-FMA) with optimal block ratios that favor the formation of polymersomes in aqueous media having pH-responsive P(DPA-co-FMA) membranes. Owing to the existence of furfuryl pendant groups within the polymersome membranes, the crosslinking of pH-responsive P(DPA-co-FMA) chains can be achieved via Diels-Alder chemistry. Interestingly, the resulting crosslinked polymersomes swell when the pH in the solution is decreased so that it lies in a biologically relevant range, as was demonstrated by cryogenic transmission electron microscopy. Here, the polymersomes' ability to swell can be controlled by adjusting the amount of crosslinker. A minimum threshold of crosslinking density is needed for the polymersomes to swell while an excess amount of crosslinker quenched their ability to swell. Furthermore, crosslinked polymersomes are capable of encapsulating hydrophilic model drug, such as Rhodamine B. At pH 7.20, due to the compact and hydrophobic membrane, the diffusion of the dye from the interior of the polymersomes to the media is minimized, while the pronation of PDPA at an acidic pH of 4.00, enables a permeable membrane, allowing the loaded cargo to leak much more quickly. The shape-persistent polymersomes that we developed herein, are a promising nano-platform for use in drug delivery applications.

Cu(0)-mediated reversible-deactivation radical polymerization of n-butyl acrylate in suspension

Cu(0)-mediated reversible-deactivation radical polymerization of n-butyl acrylate was performed in suspension without the use of an organic solvent. In all cases, a 5 v% organic phase (monomer, initiator, and ligand) was used with respect to 95 v% aqueous phase. Polyvinyl alcohol (PVA) as a suspension stabilizer has been shown to be able to control the polymerization for the degree of polymerizations of 222 and higher. The polymerization reaction showed linear first-order kinetics for a PVA concentration range of 1–10 wt%, leading to polymers with dispersities from 1.22 to 1.43. Conversions as high as 96% were obtained in 55 min. Scanning electron microscopy analysis of the suspensions confirmed the formation of micron-sized polymer particles dispersed in aqueous media, and that the size of the particles decreased with increasing PVA concentration. Rheometry measurements of the aqueous phase containing PVA before and after polymerization demonstrated the increase in the viscosity of the reaction mixture after polymerization. The difference between the viscosity of the PVA solution in water and the same solution after polymerization decreased as the PVA decreased, which indicates smaller particle sizes formed with increasing PVA content. All suspensions were stable over a period of three months storage at room temperature without any precipitation or sedimentation. The maximum copper species concentration in the reaction medium and water can be as low as 7 ppm. This Cu(0)-mediated reversible-deactivation radical polymerization in suspension has the potential for industrial use, especially for paint and adhesives.

Mussel-inspired V-shaped copolymer coating for intelligent oil/water separation

Successful fabrication of mussel-inspired V-shaped copolymer based materials for pH controllable oil/water separation was reported. Triblock copolymer, polydimethylsiloxane-block-poly(2-hydroxyethyl methacrylate)-block-poly(2-(dimethylamino)ethyl methacrylate) (PDMS-b-PHEMA-b-PDMAEMA) was designed and synthesized through copper(0)-mediated reversible-deactivation radical polymerization (RDRP). Hydroxyl-containing PHEMA block enabled the covalent reaction to occur between polymer and polydopamine (PDA) functionalized substrates. The mixed polymer brushes of oleophilic/hydrophobic PDMS and pH-responsive PDMAEMA endowed the substrates with good pH responsive oil/water wettability and stability. As a proof of concept, the functionalized mesh can separate a range of different immiscible oil/water mixtures with high separation efficiency over 98.5% and high oil flux of 8800–9500Lh−1m−2 and water flux of 7400–7800Lh−1m−2. Additionally, the functionalized sponge realized reversible oil capture and release in aqueous media. Because dopamine through self-polymerization can form strong adhesive films on inorganic and organic substrates in alkalescence solution, the method used in current contribution would be also suitable for producing polymer brush functionalized intelligent materials based on other common substrates.

Rapid Synthesis of Well-Defined Polyacrylamide by Aqueous Cu(0)-Mediated Reversible-Deactivation Radical Polymerization

Atom transfer radical polymerization (ATRP) of acrylamide (AM) has proved challenging, typically exhibiting low conversions and broad molecular weight distributions (MWDs). Herein, we report the synthesis of well-defined polyacrylamide (both homo and block copolymers) via aqueous copper(0)-mediated reversible-deactivation radical polymerization (Cu(0)-RDRP), exploiting the in situ disproportionation of Cu(I)Br in the presence of Me6Tren to yield insoluble Cu(0) and Cu(II)Br2 which acts as a deactivator. Careful optimization of the levels of Cu(I)Br and Me6TREN allowed for the synthesis of polyacrylamide of a range of molecular weights (DPn = 20–640) proceeding to quantitative conversion within just a few minutes (typically full conversion is attained within 15 min of reaction time) and exhibiting narrow MWDs (Đ as low as 1.09), which represents a significant improvement over transitional-metal-mediated approaches previously reported in the literature. This optimized approach was subsequently utilized to p...

Preparation of corn stalk-based adsorbents and their specific application in metal ions adsorption

AbstractCorn stalk-based adsorbents modified from corn stalk were prepared by Cu(0)-mediated reversible-deactivation radical polymerization (Cu(0)-mediated RDRP). They were applied to remove metal ions and they exhibited good adsorption capacity, especially for Hg(II). Adsorption properties of corn stalk can be enhanced by introducing cyano, amino, amidoxime, and carboxyl groups onto its surface, which results in efficient adsorbents for different metal ions. TGA, SEM, EA, and FTIR analyses were employed to characterize the structures of corn stalk-

Smart Fiber Membrane for pH-Induced Oil/Water Separation.

Wastewater contaminated with oil or organic compounds poses threats to the environment and humans. Efficient separation of oil and water are highly desired yet still challenging. This paper reports the fabrication of a smart fiber membrane by depositing pH-responsive copolymer fibers on a stainless steel mesh through electrospinning. The cost-effective precursor material poly(methyl methacrylate)-block-poly(4-vinylpyridine) (PMMA-b-P4VP) was synthesized using copper(0)-mediated reversible-deactivation radical polymerization. The pH-responsive P4VP and the underwater oleophilic/hydrophilic PMMA confer the as-prepared membrane with switchable surface wettability toward water and oil. The three-dimensional network structure of the fibers considerably strengthens the oil/water wetting property of the membrane, which is highly desirable in the separation of oil and water mixtures. The as-prepared fiber membrane accomplishes gravity-driven pH-controllable oil/water separations. Oil selectively passes through the membrane, whereas water remains at the initial state; after the membrane is wetted with acidic water (pH 3), a reverse separation is realized. Both separations are highly efficient, and the membrane also exhibits switchable wettability after numerous cycles of the separation process. This cost-effective and easily mass-produced smart fiber membrane with excellent oil-fouling repellency has significant potential in practical applications, such as water purification and oil recovery.

Fluorescent dye-labeled TIPNO type regulator for nitroxide mediated reversible-deactivation radical polymerization

Abstract The TIPNO-type mediator containing fluorescent probe was used to initiate nitroxide mediated reversible-deactivation radical polymerization of styrene. Benzothioxanthene and pyrene were the fluorescent markers. One probe, benzothioxanthene, was attached to the initiating fragment of the polymer chain and the second probe, pyrene, was part of the propagating end of the polymer chain. Mainly UV absorption as well as partly fluorescence spectroscopy was applied to quantify the marked initiating chain ends and marked active alkoxyamine-terminated chain ends. Calculated theoretical molar masses are based on the assumption that all the initiating and propagating chain ends of the polymers bear fluorescent probes. Comparison of these data with the molar masses from GPC gave us the fraction of the marked active polymer chain ends and the fraction of polymers that were formed by thermal initiation. This represents a unique method for evaluation of the extent of livingness of polymerization process. At lower mediator concentration, the extent of marked initiating chain ends and the extent of marked propagating chain ends decreased with rising conversion and at 40% conversion only 50% of the polymer initiating and propagating chain ends contained labels. For the higher mediator concentration, marked initiating fragments of polymer chains were 95% and marked propagating chain ends were 93% at 40% conversion. The prepared polymers are characterized by a narrow distribution of molar masses for all conversion scales.

Ligand effect and oxygen tolerance studies in photochemically induced copper mediated reversible deactivation radical polymerization of methyl methacrylate in dimethyl sulfoxide

Well-defined PMMA can be prepared using photoRDRP without the necessity of degassing of MMA and/or DMSO.

The effect of ligand, solvent and Cu(0) source on the efficient polymerization of polyether acrylates and methacrylates in aqueous and organic media

The synthesis of well-defined telechelic polyacrylates and polymethacrylates in organic and aqueous media via Cu(0)-mediated reversible-deactivation radical polymerization is thoroughly investigated.

Thermal-Responsive Block Copolymers for Surface with Reversible Switchable Wettability

A series of thermal-responsive block copolymers, i.e., poly(methyl methacrylate)-block-poly(N-isopropylacrylamide) (PMMA-b-PNIPAAm), were successfully synthesized via successive copper(0)-mediated reversible-deactivation radical polymerization technology. Thermal properties of block copolymers with different PNIPAAm chain lengths were investigated by differential scanning calorimetery (DSC) and thermogravimetric analysis (TGA). The well-separated glass transition temperature values shown in DSC results indicate that two chemically different blocks, PNIPAAm and PMMA, are incompatible and phase-segregated. The thermal degradation results show that the thermal stability of these copolymers was improved through incorporating the PNIPAAm segments. The PMMA120-b-PNIPAAm86 and PMMA120-b-PNIPAAm130 maintain stability and undergo one-stage degradation when the temperature increases above 360 °C. Because of the synergistic effect of copolymer composition and copolymer film roughness, the obtained reversible thermal-responsive wettability for the resulting copolymer-modified surfaces is different, which is enhanced by incorporating more functional NIPAAm units. Specifically, the variations of the static water contact angle for the surfaces fabricated by PMMA120-b-PNIPAAm40, PMMA120-b-PNIPAAm54, PMMA120-b-PNIPAAm86, and PMMA120-b-PNIPAAm130 are 18.7, 20.4, 26.8, and 34.3°, respectively. In addition, all as-prepared surfaces present a stable reversible thermal-responsive wettability, which can be applied to coatings with temperature-controllable wettability as well as manipulation of liquids in microfluidic devices.

Copper(0)-Mediated Reversible-Deactivation Radical Polymerization: Kinetics Insight and Experimental Study

A comprehensive kinetic model based on the mechanism of supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) was developed to better understand the kinetics of copper(0)-mediated reversible-deactivation radical polymerization [Cu(0)-mediated RDRP]. Simulation results show that diffusional limitation on termination significantly affects on polymerization. A comprehensive description of the variation trend of soluble species and reaction rates during polymerization was illustrated by simulation. The effects on kinetics of four key rate constants (i.e., ka0, kdisp, ka1, kcomp) involved in Cu(0)-mediated RDRP were investigated in detail, which contributed to greater insight into the differences between the SET-LRP and SARA ATRP mechanisms. Finally, Cu(0)-mediated RDRPs of methyl methacrylate (MMA) and butyl methacrylate (BMA) were conducted to study the polymerization kinetics at 25 °C. Results of simulations and experiments performed under polymerization conditions show ...