Reversible Addition-fragmentation Chain Transfer Method Research Articles

Multiresponsive Behavior of the Pickering Emulsifier and Its Application for Collecting Small Oil Droplets in Water.

Responsive Pickering emulsions, with unique nanoparticle interfaces and sensitivity to external stimuli, significantly enhanced the stability and applicability of Pickering emulsions. Multifunctional composite material poly((2-(dimethylaminoethyl methacrylate)-b-(acrylate cyclodextrin))/Fe3O4 nanoparticles, namely P(DMAEMA-b-A-CD)/Fe3O4, with both multiresponsive characteristics and emulsifying capabilities had been designed to remove small oil droplets from water. Using the reversible addition-fragmentation chain transfer (RAFT) method, diblock polymers P(DMAEMA-b-A-CD) were grown in a controlled manner on the surface of Fe3O4. The Fe3O4 core showed responsiveness to a magnetic field, and the block copolymers prepared via the RAFT method demonstrated reactivity to both pH and CO2. The P(DMAEMA-b-A-CD)/Fe3O4 nanoparticles exhibited the capability to form Pickering/Oxford emulsions with exceptional stabilization properties. It could be observed that the introduction of CO2, acid, and a magnetic field led to the breakage of the emulsion, while the emulsion could be restabilized by removing the CO2 and the magnetic field or by adding alkali. Measurements of interfacial tension, ζ-potential, and contact angle demonstrated that the emulsification/breakdown mechanisms associated with pH and CO2/N2 were related to the surface wettability of the nanoparticles. In addition, the emulsifier had an excellent cycling capacity with at least 10 cycles by CO2/N2. Additionally, P(DMAEMA-b-A-CD)/Fe3O4 nanoparticles exhibited excellent stability in oil phases with large polarity differences and various real oil phases with different viscosities. Importantly, the P(DMAEMA-b-A-CD)/Fe3O4 nanoparticles could serve as functional materials for efficiently separating small oil droplets from water through the application of a magnetic field. Therefore, P(DMAEMA-b-A-CD)/Fe3O4 nanoparticles held promising potential as materials with economic and commercial value for oil-water separation applications.

Fiber Spinning of Polyacrylonitrile Terpolymers Containing Acrylic Acid and Alkyl Acrylates

Terpolymers of acrylonitrile with acrylic acid and alkyl acrylates, including methyl-, butyl-, 2-ethylhexyl-, and lauryl acrylates, were synthesized using the reversible addition–fragmentation chain transfer method. In this study, the focus was on the investigation of the impact of different monomer addition methods (continuous and batch) on both the rheological behavior of the spinning solutions and the mechanical properties of the resulting fibers. Our findings revealed that the method of monomer addition, leading either to non-uniform copolymers or to a uniform distribution, significantly influences the rheological properties of the concentrated solutions, surpassing the influence of the alkyl-acrylate nature alone. To determine the optimal spinning regime, we examined the morphology and mechanical properties at different stages of fiber spinning, considering spin-bond and orientation drawings. The fiber properties were found to be influenced by both the nature and introducing method of the alkyl-acrylate comonomer. Remarkably, the copolymer with methyl acrylate demonstrates the maximum drawing ratios and fiber tensile strength, reaching 1 GPa. Moreover, we discovered that continuous monomer addition allows for reaching the higher drawing ratios and superior fiber strength compared to the batch method.

Water soluble β-CD-PMAA/PMAm/PHEMA-Coumarin macromolecular fluorescent probes prepared via RAFT method and their sensing ability to Fe3+/Fe2+ and Cu2+ ions

Developing water-soluble fluorescent probes has important scientific and practical significance. In this work, coumarin derivatives bearing -OH were obtained through the classical Knoevenagel reaction firstly. Secondly, -CC- on allyl bromide was introduced into coumarin by Williamson ether formation method. Thirdly, hydrazine hydrate was added to the coumarin derivatives, a polymerizable small molecular coumarin fluorophore containing probe was obtained successfully. And, the -COOH on di-thioester underwent an esterification reaction with –OH groups on β-cyclodextrin(β-CD) to prepare oligomer based reversible addition-fragmentation chain transfer(RAFT) reagents. Finally, three copolymer probes β-CD-PMAA-Coumarin, β-CD-PMAm-Coumarin, and β-CD-PHEMA-Coumarin were prepared via RAFT polymerization, in which CC-coumarin was used as the functional monomer and methacrylamide(MAm)/methacrylic acid (MAA)/hydroxyethyl methacrylate (HEMA) as the main monomers. The MALDI-TOF mass tests showed that the macromolecular level probes were successfully prepared. These polymer probes have molecular weights up to 5.4 kDa and have narrow molecular weight distributions (PDI≤1.31). With the assistance of water-soluble long-chained PMAm/PMAA/PHEMA and hydrophilic β-CD, the coumarin containing macromolecular fluorescent probes could be dissolved in water readily. These water soluble polymer fluorescent probes could recognize Fe3+/Fe2+ and Cu2+ ions with high sensitivity. The detection limit of Fe3+ could be as low as 0.34 μM. This study successfully developed a promising technique for producing highly selective, fully water-soluble fluorescent macromolecular probes.

Preparation of Water-Soluble Polyion Complex (PIC) Micelles with Random Copolymers Containing Pendant Quaternary Ammonium and Sulfonate Groups.

Cationic random copolymers (PCm) consisting of 2-(methacryloyloxy)ethyl phosphorylcholine (MPC; P) with methacroylcholine chloride (MCC; C) and anionic random copolymers (PSn) consisting of MPC and potassium 3-(methacryloyloxy)propanesulfonate (MPS; S) were prepared via a reversible addition-fragmentation chain transfer method. "m" and "n" represent the compositions (mol %) of the MCC and MPS units in the copolymers, respectively. The degrees of polymerization for the copolymers were 93-99. Water-soluble MPC unit contains a pendant zwitterionic phosphorylcholine group whose charges are neutralized in pendant groups. MCC and MPS units contain the cationic quaternary ammonium and anionic sulfonate groups, respectively. The stoichiometrically charge-neutralized mixture of a matched pair of PCm and PSn aqueous solutions resulted in the spontaneous formation of water-soluble PCm/PSn polyion complex (PIC) micelles. These PIC micelles have the MPC-rich surface and MCC/MPS core. These PIC micelles were characterized using 1H NMR, dynamic and static light scattering, and transmission electron microscopic measurements. The hydrodynamic radius of these PIC micelles depends on the mixing ratio of the oppositely charged random copolymers. The charge-neutralized mixture formed maximum-size PIC micelles.

Organic-soluble chitosan-g-PHMA (PEMA/PBMA)-bodipy fluorescent probes and film by RAFT method for selective detection of Hg2+/Hg+ ions

Chitosan as the plentiful and easily available natural polymer, its solubility in organic solvents is still a challenge. In this article, three different chitosan-based fluorescent co-polymers were prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization. They could not only dissolve in several organic solvents, but also could selectively recognize Hg2+/Hg+ ions. Firstly, allyl boron-dipyrrolemethene (bodipy) was prepared, and used as one of the monomers in the subsequent RAFT polymerization. Secondly, chitosan-based chain transfer agent (CS-RAFT) was synthesized through classical reactions for dithioester preparation. Finally, three methacrylic ester monomers and bodipy bearing monomers were polymerized and grafted as branched-chains onto chitosan respectively. By RAFT polymerization, three chitosan-based macromolecular fluorescent probes were prepared. These probes could be readily dissolved in DMF, THF, DCM, and acetone. All of them exhibited the ‘turn-on’ fluorescence with selective and sensitive detection for Hg2+/Hg+. Among them, chitosan-g-polyhexyl methacrylate-bodipy (CS-g-PHMA-BDP) had the best performance, its fluorescence intensity could be increased to 2.7 folds. In addition, CS-g-PHMA-BDP could be processed into films and coatings. When loading on the filter paper, fluorescent test paper was prepared and it could realize the portable detection of Hg2+/Hg+ ions. These organic-soluble chitosan-based fluorescent probes could enlarge the applications of chitosan.

Recent Advances in the Biomedical Applications of Functionalized Nanogels.

Nanomaterials have been extensively used in several applications in the past few decades related to biomedicine and healthcare. Among them, nanogels (NGs) have emerged as an important nanoplatform with the properties of both hydrogels and nanoparticles for the controlled/sustained delivery of chemo drugs, nucleic acids, or other bioactive molecules for therapeutic or diagnostic purposes. In the recent past, significant research efforts have been invested in synthesizing NGs through various synthetic methodologies such as free radical polymerization, reversible addition-fragmentation chain-transfer method (RAFT) and atom transfer radical polymerization (ATRP), as well as emulsion techniques. With further polymeric functionalizations using activated esters, thiol-ene/yne processes, imines/oximes formation, cycloadditions, nucleophilic addition reactions of isocyanates, ring-opening, and multicomponent reactions were used to obtain functionalized NGs for targeted delivery of drug and other compounds. NGs are particularly intriguing for use in the areas of diagnosis, analytics, and biomedicine due to their nanodimensionality, material characteristics, physiological stability, tunable multi-functionality, and biocompatibility. Numerous NGs with a wide range of functionalities and various external/internal stimuli-responsive modalities have been possible with novel synthetic reliable methodologies. Such continuous development of innovative, intelligent materials with novel characteristics is crucial for nanomedicine for next-generation biomedical applications. This paper reviews the synthesis and various functionalization strategies of NGs with a focus on the recent advances in different biomedical applications of these surface modified/functionalized single-/dual-/multi-responsive NGs, with various active targeting moieties, in the fields of cancer theranostics, immunotherapy, antimicrobial/antiviral, antigen presentation for the vaccine, sensing, wound healing, thrombolysis, tissue engineering, and regenerative medicine.

In vitro DNA plasmid condensation and transfection through pH-responsive nanohydrogel.

Nanohydrogels (NHs) with the benefits of both nanomaterials and hydrogels unlock novel opportunities and applications in biomedicine. Nowadays, cationic NHs have attracted attention in the delivery of genetic materials into cells. Herein, by using reversible addition-fragmentation chain transfer method, an NH-based poly(hydroxyethyl methacrylate-co-N,N-dimethylaminoethyl methacrylate) and cross-linked by poly(ethylene glycol)diacrylate with pH responsiveness character was developed. Several techniques including nuclear magnetic resonance, Fourier-transform infrared spectroscopy, and gel permeation chromatography confirmed the success in the synthesis. The pH responsiveness of the developed NH was shown by transmission electron microscopy and dynamic light scattering technique. The average sizes of NHs in the normal (7.4) and acidic pH (5.5) were 180 and 390nm, respectively. The ability of the developed NH to condense genetic materials was checked using gel retardation assay with different ratios of NH and pCMV6-IRES-AcGFP, as a plasmid encoding green fluorescence protein. Results of gel retardation assay showed a decreasing trend in plasmid electrophoretic mobility with the increase in the NH concentration. The NH/plasmid complexes were stopped completely at the ratio of 5 and the plasmid band vanished at the ratio of 10. The quantitative and qualitative results of the cell transfection experiment using different ratios of NH/plasmid showed the ability of NH to carry plasmid molecules into the cancerous cells. The best transfection efficiency was observed by nanohydrogel/plasmid weight ratio of 10, while other ratios including 2, 5 and 20 showed 0.8, 10 and 12% of transfection efficiency, respectively. All the assessed factors showed that NH has the potential to be considered as an efficient gene delivery vehicle.

The inhibitory effect of curcumin loaded poly (vinyl caprolactam) nanohydrogel on insulin fibrillation

Amyloidosis refers to a group of diseases caused by the deposition of abnormal proteins in tissues. Herein, curcumin was loaded in a nanohydrogel made of poly (vinylcaprolactam) to improve its solubility and was employed to exert an inhibitory effect on insulin fibrillation, as a protein model. Poly (vinyl caprolactam), cross-linked with polyethylene glycol diacrylate, was synthesized by the reversible addition-fragmentation chain transfer method. The release profile of curcumin exhibited a first-order kinetic model, signifying that the release of curcumin was mainly dominated by diffusion processes. The study of curcumin release showed that 78% of the compound was released within 72 h. The results also revealed a significant decline in insulin fibrillation in the presence of curcumin-loaded poly (vinyl caprolactam). These observations confirmed that increasing the ratio of curcumin-loaded poly (vinyl caprolactam) to insulin concentration would increase the hydrogel’s inhibitory effect (P-value < 0.05). Furthermore, transmission electron and fluorescence microscopies and Fourier-transform infrared spectroscopy made it possible to study the size and interaction of fibrils. Based on the results, this nanohydrogel combination could protect the structure of insulin and had a deterrent effect on fibril formation.

Synthesis of core-shell structure based on silica nanoparticles and methacrylic acid via RAFT method: An efficient pH-sensitive hydrogel for prolonging doxorubicin release

In recent years, much attention has been received on stimuli-responsive nanocarriers in nanomedicine. In this work, a pH-responsive core-shell system based on silica nanoparticles (SNPs) as core and methacrylic acid hydrogels as shell were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Methacrylic acid hydrogel through bulk and RAFT polymerization was developed as a model to compare with core-shell hydrogel. The synthesized nanocarriers were characterized by TGA, FT-IR, SEM, TEM, and DLS techniques. To investigate the synthesized core-shell nanoparticles as anticancer nanocarriers, Doxorubicin (DOX) was used as a model drug. In-vitro drug release manner at physiological barriers (pH 7.4) and cancer cell conditions (pH 4.8) illustrates a pH-controlled release for the nanocarriers over 15 days. The study of drug release kinetics reveals that the release mechanism of the carriers followed by the Gompertz model. In addition, the DOX-loaded nanocarriers have notable cytotoxicity against human breast MCF-7 cells with 0.7866 μM IC50 for core-shell nanocarrier. The obtained results showed that the prepared pH-responsive core-shell hydrogel has a high potential to be employed as a sustained pH-sensitive drug release system.

Fully-water-soluble BODIPY containing fluorescent polymers prepared by RAFT method for the detection of Fe3+ ions

The development of water-soluble polymer dyes is of great practical and scientific significance. In this article, small fluorescent molecule boron-dipyrromethene (BODIPY) bearing C=C bond was synthesized first. And then, via Suzuki reaction, recognition groups were introduced into the 2, 6 positions of BODIPY. Thus polymerizable fluorescent monomers were prepared. Finally, methacrylic acid (MAA) was copolymerized with the as-prepared small molecular fluorescent monomers via reversible addition-fragmentation chain transfer (RAFT) polymerization methodology. Four fully-water-soluble polymer sensors with BODIPY moieties in the end of the polymer chain were obtained eventually. In the presence of long PMAA chain, and by the assistance of it, BODIPY could be dissolved totally in water. These polymer sensors exhibited sensitive and selective recognition ability to Fe3+. Even the content rate of BODIPY was as low as 0.5% of the polymer (calculated from element analysis), the detection limit could reach 1.2 μM. The sensors with two recognition groups in one BODIPY unit were more sensitive than that with one recognition groups in each BODIPY unit. The sensing mechanism was investigated as well. By endowing the water solubility to organic sensors, the application scope could be greatly enlarged in sensing metal ions in aqueous environments. This work provides a method to develop water soluble high performance polymer sensors.

Synthesis of Lignin-Based MMA-co-BA Hybrid Resins from Cornstalk Residue via RAFT Miniemulsion Polymerization and Their Characteristics.

The conversion of cornstalk lignin derived from the co-product of bio-refinery into value-added products such as polymeric material has remarkable environmental and economic potential. A novel bio-based methyl methacrylate copolymerized with butyl acrylate (MMA-co-BA) hybrid resin in our research was prepared by the reversible addition–fragmentation chain transfer method using lignin-graft-polyacrylamide (lignin-g-PAM) as a bio-derived macromolecular chain transfer agent. The molecular architecture of lignin-g-PAM and the lignin-based MMA-co-BA hybrid resin was elucidated using 1H nuclear magnetic resonance and attenuated total reflectance–Fourier transform infrared. The thermal behavior and mechanical performance of the resultant lignin-based MMA-co-BA hybrid resins were also investigated through thermogravimetric analysis, differential scanning calorimetry, and a stress–strain test, respectively. The lignin-based acrylate resins system exhibited structure-related thermal and mechanical properties. Compared with pure MMA-co-BA resin, the incorporation of lignin into various lignin-based MMA-co-BA graft copolymers resulted in an improved tensile strength and a higher Young’s modulus. This research could provide not only a new avenue to utilize waste biomass for high-value applications, but also a reference for designing new materials for coatings or adhesives.

RAFT Method for Preparation of Molecularly Imprinted Polymer–SBA15 Nanocomposite as a Pipette Tip Solid-Phase Microextraction Adsorbent

Methoxyfenozide-selective surface molecularly imprinted polymer (MIP) sorbent was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization based on support matrix of SBA-15. The size, morphology, composition, and properties of the prepared nanocomposite have also been characterized and determined using scanning electron microscopy (SEM) and Fourier-transform- infrared (FT-IR) spectroscopy. A miniaturized solid-phase extraction procedure has been developed for ultra-trace determination of methoxyfenozide adsorbed on polymethacrylic acid-functionalized Santa Barbara Amorphous type material (SBA-15), which is packed into a pipette- tip (PT). The PT-SPE was assembled by packing 2.0 mg of nanocomposite of MIP as sorbent into a 100 μL pipette tip. The method was optimized for several important extraction parameters such as sample volume, pH, amount of sorbent, and eluent solvent. The results determine that the prepared adsorbent has a high extraction power. High sensitivity, non-use of organic solvent, high selectivity, and low detection limits are the unique advantages of the proposed method.

Integrin receptor mediated pH-responsive nano-hydrogel based on histidine-modified poly(aminoethyl methacrylamide) as targeted cisplatin delivery system

The aim of this project was to synthesize a novel nano-hydrogel (NH) and application of this nanomaterial to targeted delivery of cisplatin. The nano-hydrogel (NH) based on random copolymerization of aminoethyl methacrylamide cross-linked with polyethylene glycol dimethacrylate, was fabricated by reversible addition-fragmentation chain transfer method. l-histidine was conjugated to the backbone of the prepared structure. Then, the complexation of cisplatin with NHs was accomplished and tetraiodothyroacetic acid was conjugated to this structure. The NH structure was characterized by FT-IR and 1H NMR analyses. Particle sizes, ζ-potential, molecular weight, and morphology of NHs were determined. The concentrations of cisplatin during drug loading and release studies were quantified using ICP-OES. The cytotoxicity of NHs was evaluated by the MTT assay in HEK293 and HT29 cell lines. Finally, the plasma profiles of the developed NHs were evaluated in Sprague Dawley rats and pharmacokinetic parameters were calculated. The proposed nano-platform is capable of responding to pH changes in the tumor microenvironment and can actively target the cancerous cells more efficiently than free cisplatin in HT29 cells and potentially can serve as an anti-cancer agent. Also, the enhancement of pharmacokinetic parameters of cisplatin loaded NH, compared with free cisplatin, revealed that the development of NH as a carrier system for cisplatin could be promising. Suitable nano size, relatively good hemo-compatibility, pH-responsive drug release pattern, active targeting via integrin receptors, and improvement of pharmacokinetic parameters are the exquisite features in this NH formulation.

Thermal Properties and Self-Assembly Behaviors of Triblock Copolymers Consisting of PEG Segment and Acrylamide-Based Block Bearing Alkyl Side Chains Prepared by RAFT Method

A new series of hybrid triblock copolymers (TBCs) based on hard–soft–hard segments are synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization using a macroinitiator p...

The Effect of the Synthetic Procedure of Acrylonitrile-Acrylic Acid Copolymers on Rheological Properties of Solutions and Features of Fiber Spinning.

The influence of introducing acrylic acid (AA) into the reaction mixture with acrylonitrile at the synthesis of copolymers by free-radical polymerization (FRP) and radical polymerization with reversible addition–fragmentation chain transfer (RAFT) on the rheological properties of their solutions in dimethyl sulfoxide, as well as on the capability to spin fibers by the mechanotropic method, is analyzed. The influence of AA dosing conditions on the rheological properties of the solutions in the concentration range above the crossover point was not revealed. In the case of RAFT synthesis, the rheological properties differ distinctively in the high concentration region that is expressed by unusual viscoelastic characteristics. Dilute solution viscometry revealed the influence of the comonomer loading order on the interaction intensity of the copolymer macromolecules with a solvent, which is more pronounced for samples synthesized by FRP and can be associated with the copolymers’ molecular structure. Fiber spinning from solutions of polyacrylonitrile and its copolymers (PAN) synthesized by the RAFT method was not able to achieve a high degree of orientation drawing, while for polymers with a wider molecular weight distribution synthesized by FRP, it was possible to realize large stretches, which led to high-quality fibers with strength values up to 640 MPa and elongation at a break of 20%.

Synthesis of 4-acetoxystyrene – t-butyl acrylate statistical, block and gradient copolymers, and the effect of the structure of copolymers on their properties

The properties of copolymers are affected greatly by the composition as well as the chain structure of the copolymers. Consequently, gradient copolymers, due to the uniqueness of their structures show significantly different properties than those of the conventional statistical and block copolymers. This study reports the synthesis of 4-acetoxystyrene – t-butyl acrylate (AOST-tBA) statistical copolymers by reversible addition-fragmentation chain-transfer (RAFT) and free radical polymerization (FRP) methods, and also the synthesis of block and gradient copolymers of AOST-tBA by the RAFT method. The gradient structure in the AOST-tBA copolymer was produced by continuously adding a second monomer to the polymerization system to taper the copolymer composition. Differential scanning calorimetry (DSC) analysis found a broad transition for the gradient copolymer, in contrast to a single narrow transition for the statistical copolymer and two narrow transitions for the block copolymer. The acetoxy groups from the AOST-tBA copolymers were de-acetylated to convert the AOST to hydroxystyrene (HOST). Fourier transform infra-red (FTIR) studies revealed that the extent of hydrogen bonding in thin films of the HOST-tBA copolymers is greatly influenced by the copolymer composition as well as the chain structure. However, no significant differences were found for the surface compositions and surface free energies of copolymers. The properties of HOST-tBA copolymers synthesized by RAFT and FRP have also been compared in this study.

Modification of cellulose nanocrystal with dual temperature- and CO2-responsive block copolymers for ion adsorption applications

Cellulose nanocrystal (CNC)-grafted smart polymers have potential applications as adsorbents by providing simple regeneration process. In this study, carbon dioxide (CO2)- and temperature-responsive free block copolymers of N-isopropylacrylamide and (2-dimethylaminoethyl) methacrylate with different block lengths were synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. In addition, CNC was modified with the similar block copolymers by surface-initiated RAFT method. The synthesized block copolymers were used in nitrate ion removal from aqueous solutions. The synthesis process was confirmed by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance (1H NMR) analysis, thermal gravimetric analysis, scanning electron microscopy, and transmission electron microscopy. Stimuli-responsivity of the free polymers was studied by pH measurement, turbidity investigation, and dynamic light scattering analysis. CO2-responsivity of the block copolymers in aqueous solution was confirmed by reduction of pH in the presence of CO2 by protonation of the PDMAEMA blocks. The copolymers with higher length of PDMAEMA showed highly intense CO2-responsivity. Deprotonation of the PDMAEMA units by purging N2 represents reversible responsivity of the copolymers. Turbidity analysis showed different critical solution temperatures (CST) for the block copolymers with various block lengths. Two different micellar and vesicular morphologies were observed for the self-assembled copolymers at temperatures above and below CST of the copolymers, which is related to the hydrophobic/hydrophilic block ratio. CO2-switched nitrate ion adsorption from aqueous solution at two temperatures (37 and 60 °C) was studied by UV–vis spectroscopy using the synthesized products as adsorbent. Adsorption of nitrate ions from aqueous solutions was increased by protonation of the PDMAEMA segments upon CO2 purging. Presence of CNC, morphology of the self-assembled copolymers, temperature, and time of CO2 purging affect the nitrite ion adsorption capacity. The maximum adsorption capacity (420 mg/g) is related to the sample with vesicular assemblies in aqueous solution and higher PDMAEMA block length at temperatures below CST of the block copolymer. N2 purging resulted in deprotonation of the PDMAEMA blocks and regeneration of the samples. Finally, the CNC substrate can be used in regeneration of the samples with simple filtration process in addition to the stimuli-regeneration process.

Synthesis of bioactive polyaniline-b-polyacrylic acid copolymer nanofibrils as an effective antibacterial and anticancer agent in cancer therapy, especially for HT29 treatment.

In this work, a new highly water-soluble copolymer of polyacrylic acid with polyaniline is introduced. Acrylic acid was polymerized via the Reversible Addition Fragmentation Chain Transfer method (RAFT) in the presence of an initiator and the obtained polyacrylic acid was copolymerized with aniline at room temperature. As the main achievements of this work, the resulting block copolymer with nanosized structure revealed favorable solubility in polar solvents, as well as excellent antibacterial and anticancer activities. Therefore, it is an appropriate candidate for medical applications such as wound healing and cancer therapy, especially in HT29 treatment.

Stereoelectronically Directed Photodegradation of Poly(adamantyl Vinyl Ketone).

Adamantyl vinyl ketone (AVK) and its copolymers are synthesized using reversible addition fragmentation chain-transfer (RAFT) methodology and then degraded using UV light. The polymerization of AVK is found to be controlled as indicated by a linear correlation between the molecular weights of the polymers produced and monomer conversion as well as a series of chain extensions. The RAFT method is also used to synthesize random and block copolymers of AVK and methyl methacrylate. Irradiating poly(adamantyl vinyl ketone) (PAVK) with UV light affords a polyolefin and adamantane as the major products. Similar products are obtained, along with poly(methyl methacrylate) (PMMA), when the block copolymer is subjected to UV light. The random copolymer undergoes complete degradation under similar conditions. A mechanism wherein stereoelectronic effects channel photodegradation through Norrish I Type pathways in a manner that preserves the main chain of the polymer during the decomposition process is proposed.

Anti-fouling and thermosensitive ion-imprinted nanocomposite membranes based on grapheme oxide and silicon dioxide for selectively separating europium ions

The increasing amount of europium in aqueous environment from rare earth industry has become a serious environmental challenge. Significant efforts have been focused on ion-imprinting membranes (IIMs) for selective separation of ions from analogues. Based on ion-imprinting technique, we have developed Eu3+-imprinted nanocomposite membranes (Eu-IIMs) for selectively separating Eu3+ from La3+, Gd3+ and Sm3+. Polydopamine (pDA) was previously synthesized on basal membranes to augment the interfacial adhesion. Grapheme oxide (GO) and modified silicon dioxide (kSiO2) were synergistically stacked on pDA-modified substrates to form hydrophilic nanocomposite membranes. Ag nanoparticles were modified on the surface to enhance anti-fouling performance. The temperature-controlled selective recognition sites were formed using N-isopropylacrylamide (NIPAm) and acrylamide (Am) as functional monomers as well as europium ions as templates by RAFT (reversible addition-fragmentation chain transfer) method. Large enhanced Eu3+-rebinding capacity (101.14 mg g−1), adsorptive selectivity (1.82, 1.57, 1.45 for Eu3+/La3+, Eu3+/Gd3+, Eu3+/Sm3+) and permselectivity (3.82, 3.47, 3.34 for La3+/Eu3+, Gd3+/Eu3+, Sm3+/Eu3+) were achieved on Eu-IIMs with superior regeneration performance. Additionally, the negligible damage of the membranes after buried for 20 d indicated the superior anti-fouling property of the Eu-IIMs. The ion-imprinted nanocomposite membranes synthesized in this work have shown great potentials for selective separation of rare earth ions.