Ionic Graft Research Articles

PEG promoted anti-fouling adsorptive membranes with excellent adsorption performance for removal of pharmaceuticals from water

Rapid and effective removal of pharmaceutical contaminants (PhCs) from water through adsorptive approach remains a huge challenge due to the multiple ionization sites and lipophilic property of most PhCs. Another issue for adsorptive media is the tough trade-off problem between adsorption enhancement and fouling-resistance. Adsorptive membranes have the advantages of convenient post-treatment and huge promise in removing PhCs compared with conventional adsorbents. Herein, two types of PEG-coupled ionic grafting adsorption membranes (NVFM-H-PEG and PPM-PMA-PEG) with outstanding adsorption and antifouling performance are developed for PhCs removal. The membranes obtained shows ultra-high water flux (up to ca. 45,000 L/(m2h) at a pressure drop of 15 cm water gravity) and outstanding protein repulsion. According to the Langmuir model, the adsorption capacity of NVFM-H-PEG toward ibuprofen (IBU) reaches at 81.3 mg/g at 45 ℃. The large negative ΔG value (−22.0 kJ/mol) reveals the strong affinity of the positively charged NVFM-H-PEG to adsorb negative PhCs at environmental concentrations (10 µg/L). A mechanism for the excellent adsorption performance of the membranes is proposed based on the synergy of hydrophobic interactions and electrostatic interaction. After ten adsorption/eluting cycles, no detectable decrease was observed in the removal efficiency (>96%) of IBU from the river contaminated with IBU. Furthermore, high removal efficiency (totally 90.8%) could be achieved from river water multi-contaminated with five PhCs using a complex of positively charged (NVFM-H-PEG) and negatively charged (PPM-PMA-PEG) membranes. This study provides a new design strategy for effective removing PhCs from contaminated water using adsorptive membrane technique.

Pharmaceutical Functionalization of Monomeric Ionic Liquid for the Preparation of Ionic Graft Polymer Conjugates

Polymerizable choline-based ionic liquid (IL), i.e., [2-(methacryloyloxy)ethyl]-trimethylammonium (TMAMA/Cl¯), was functionalized by an ion exchange reaction with pharmaceutical anions, i.e., cloxacillin (CLX¯) and fusidate (FUS¯), as the antibacterial agents. The modified biocompatible IL monomers (TMAMA/CLX¯, TMAMA/FUS¯) were copolymerized with methyl methacrylate (MMA) to prepare the graft copolymers (19-50 mol% of TMAMA units) serving as the drug (co)delivery systems. The in vitro drug release, which was driven by the exchange reaction of the pharmaceutical anions to phosphate ones in PBS medium, was observed for 44% of CLX¯ (2.7 μg/mL) and 53% of FUS¯ (3.6 μg/mL) in the single systems. Similar amounts of released drugs were detected for the dual system, i.e., 41% of CLX¯ (2.2 μg/mL) and 33% of FUS¯ (2.0 μg/mL). The investigated drug ionic polymer conjugates were examined for their cytotoxicity by MTT test, showing a low toxic effect against human bronchial epithelial cells (BEAS-2B) and normal human dermal fibroblasts (NHDF) as the normal cell lines. The satisfactory drug contents and the release profiles attained for the well-defined graft polymers with ionically bonded pharmaceuticals in the side chains make them promising drug carriers in both separate and combined drug delivery systems.

Coupling morphology control and surface I grafting for boosting the photocatalytic activity of Bi2O2[BO2(OH)] nanosheets

Photocatalytic performance of semiconductors is currently limited by low solar light utilization, rapid charge recombination and limited reactive sites. Reducing the thickness of layered photocatalysts can shorten the charge transport distance to inhibit their recombination and provide more reactive sites. Surface ionic grafting can broaden the light absorption range and promote the separation efficiency of carriers. In this work, the surface iodine ion modified Bi2O2[BO2(OH)] nanosheets are synthesized by combining the surfactant-assisted hydrothermal method and room-temperature KI solution treatment route. These nanosheets show increased photoabsorption in visible region, enlarged specific surface area and promoted charge separation. Compared with the pristine Bi2O2[BO2(OH)], the surface I- modified Bi2O2[BO2(OH)] nanosheets exhibit substantially strengthened photocatalytic performance for degradation of BPA, which increases beyond 25 times. The total organic carbon content (TOC) test reveals that the mineralization process of BPA. Electron spin resonance (ESR) measurements disclose the radicals that play dominant role in the photocatalytic process and confirm their increased yield over I- modified Bi2O2[BO2(OH)] nanosheets. In addition, BiOB-S-I2 also shows universality for degradation of a variety of high-concentration pollutants, including rhodamine B, methyl orange, methylene blue, phenol, 2,4-dichlorophenol and tetracycline hydrochloride. This study may provide a combined strategy for exploring high-performance photocatalysts via microstructure control and surface ionic decoration.

Polyethersulfone Hollow Fiber Membranes with Enhanced Hemocompatibility and Hemodialysis Performance by Hydrophilic Ionic Liquid Grafting

Polyethersulfone Hollow Fiber Membranes with Enhanced Hemocompatibility and Hemodialysis Performance by Hydrophilic Ionic Liquid Grafting

Spatially regulated activation of membrane fusogenic peptides with chaperone-like ionic copolymers

Controlled or targeted membrane lysis induced by cascades of assembly and activation of biomolecules on membrane surfaces is important in programmed cell death and host defense systems. In a previous study, we reported that an ionic graft copolymer with a polycation backbone and water-soluble graft chains, poly(allylamine)-graft-dextran (PAA-g-Dex) chaperoned folding and assembly of E5, a membrane-destructive peptide derived from influenza hemagglutinin, to its increase membrane-disruptive activity. In this study, we modified the copolymer with long acyl chains, which resulted in delivery of the copolymer to membrane surfaces of liposomes and living cells. The liposomes with PAA-g-Dex functionalized with stearic acid (PAA-g-Dex-SA) on their surfaces underwent vesicle-to-sheet conversion upon addition of E5, whereas control liposomes did not. E5 also induced selective lysis of cells incubated with PAA-g-Dex-SA. The spatially specific activation of E5 on target membrane surfaces driven by self-assembly of copolymer and activation of E5 should find application in lipid-based delivery devices and cell-based therapeutics.

Synthesis and Characterization of Ionic Graft Copolymers: Introduction and In Vitro Release of Antibacterial Drug by Anion Exchange.

Amphiphilic graft copolymers based on [2-(methacryloyloxy)ethyl]trimethyl- ammonium chloride (TMAMA) were obtained for the delivery of pharmaceutical ionic drugs, such as p-aminosalicylate (PAS) and clavunate (CLV) anions. The side chains were attached by grafting from a multifunctional macroinitiator via atom transfer radical polymerization (ATRP) to get polymers with different grafting degrees and ionic content. The self-assembling ability, confirmed by determining the critical micelle concentration (CMC) through interfacial tension (IFT) with the use of goniometry, was reduced after ion exchange (CMC twice higher than for chloride anions contained copolymers 0.005–0.026 mg/mL). Similarly, the hydrophilicity level (adjusted by the content of ionic fraction) evaluated by the water contact angle (WCA) of the polymer film surfaces was decreased with the increase of trimethylammonium units (68°–44°) and after introduction of pharmaceutical anions. The exchange of Cl− onto PAS− and CLV− in the polymer matrix was yielded at 31%–64% and 79%–100%, respectively. The exchange onto phosphate anions to release the drug was carried out (PAS: 20%–42%, 3.1–8.8 μg/mL; CLV: 25%–73%, 11–31 μg/mL from 1 mg of drug conjugates). Because of the bacteriostatic activity of PAS and the support of the action of the antibiotics by CLV, the designed water-soluble systems could be alternatives for the treatment of bacterial infections, including pneumonia and tuberculosis.

Nanocomposite Grafted Stretchable and Conductive Ionic Hydrogels for Use as Soft Electrode in a Wearable Electrocardiogram Monitoring Device

Hydrogels possessing stretchability, toughness, and conductivity together are promising candidates for soft electronics applications. In this report, ionic grafting of poly(acryloyl hydrazide) (PAHz)–silver (Ag) nanocomposites (NC) is used to improve the mechanical properties and conductivity of poly(acrylamidopropanesulfonic acid) (PAMPS) hydrogels. PAHz–Ag NCs possessing different sizes of Ag NPs (3–40 nm) are grafted in the PAMPS hydrogel matrix via −CONHNH3+---–O3S ionic linkage. The resulting PAHz–Ag NC grafted hydrogels at ∼62 wt % water content exhibited ultimate tensile strength (UTS) and fracture energy up to ∼1.14 MPa and ∼1600 J/m2, respectively. The UTS of hydrogels was dependent on the size of Ag NP in PAHz–Ag NCs, and the value increased from 0.70 to 1.14 MPa with the decrease in Ag NP size from ∼40 to 5 nm. The hydrogel samples exhibited adequate skin adhesiveness (tack adhesive strength ≈10.8 kPa), conductivity (50.5 mS/cm), and strain sensing ability (gauge factor ≈0.9), suggesting these samples are potentially useful for various soft electronics applications. As a proof of concept, the hydrogels were employed as soft electrode in an electrocardiogram (ECG) device, and the efficiency was monitored under real-time conditions. The data exhibited noise-free reproducible patterns of ECG with defined P, Q, R, S, and T peaks under different locomotion of the body, suggesting the viability of developed hydrogels for the ECG sensing applications.

Ionic Immobilization of Silicotungstic Acid on Amine‐Functionalized Zirconia: A Mesoporous Catalyst for Esterification of Maleic Acid

AbstractSilicotungstic acid (H4SiW12O40) has been immobilized onto the mesopores of amine‐functionalized zirconia by exploitation of electrostatic interactions. The ionic grafting of silicotungstic acid was confirmed by XPS, FTIR, UV/Vis‐DRS and TGA analysis. The mesoporosity of the material was confirmed through N2 adsorption/desorption analysis. The morphology of the material was established by TEM analysis. The immobilized silicotungstate material was found to be an efficient heterogeneous catalyst for selective esterification of maleic acid with butan‐1‐ol. A 98 % level of conversion of maleic acid and 82 % selectivity for dibutyl maleate within 5 h at 95 °C was achieved. The catalyst could be reused thrice without loss of activity.

Dextran-grafted polycation copolymer to enhance DNAzyme activity and refine DNAzyme-based biosensing

Event Abstract Back to Event Dextran-grafted polycation copolymer to enhance DNAzyme activity and refine DNAzyme-based biosensing Jueyuan Gao1, Naohiko Shimada1 and Atsushi Maruyama1 1 Tokyo Institute of Technology, Biomolecular Engineering, Japan Introduction: Proper folding and assembling are key processes for biopolymers to exhibit their inherent biological activities. Artificial materials that are capable of manipulate these structures of biopolymer would have variety of applications in biomedical fields. We have designed ionic graft copolymers consisting of a polyion backbone and hydrophilic graft chains of dextran to engineer folding and assembling of biopolymers, such as DNA, having opposite ionic charges. Hydrophilic graft chains of polysaccharide guarantee soluble inter-polyelectrolyte complex formation with DNA. The copolymers significantly facilitate DNA assembly including DNA duplex, triplex and quadruplex formations, In this study, we examined the copolymer to enhance activity of deoxyribozymes, DNAzymes. We showed that the copolymers considerably increased catalytic efficacy of DNAzymes having ribonuclease activity, permitting us to refine DNAzyme-based DNA sensing. Results and Discussion: Firstly, we investigated the effect of the copolymer PLL-g-Dex on ribonuclease activity of the 10-23 DNAzyme (Fig. 1) toward substrate I with 0.5 mM Mg2+ as a cofactor under multiple turnover conditions, [S]/[E] = 30[1]. Whereas in the absence of the copolymer kobs was 1.3×10-3 min-1, in the presence of the copolymer at an N/P ratio of 2, kobs was 3 fold greater. To estimate the role of the copolymer in the observed acceleration, the DNAzyme reactions were carried out under either single- or multiple-turnover conditions. In the reaction under the single-turnover condition no difference in cleavage rates was observed regardless of the presence of PLL-g-Dex. The results indicated that the copolymer did not significantly influence chemically cleavage activity of the DNAzyme. In contrast, under multiple-turnover reaction condition faster cleavage was observed in the presence of PLL-g-Dex, implying that the copolymer promoted turnover. Next, we carried out the reaction with Mn2+ which is more active cofactor than Mg2+ either in the absence or presence of the copolymer (Fig. 2). The DNAzyme activity was enhanced with increasing concentration of the copolymer. The copolymer increased the cleavage rate more than 10 fold. The activity of the copolymer was applied to DNAzyme-based nucleotide sensor, NMAzyme. The copolymer increased the MNAzyme reaction rate by 200 times, allowing target DNA detection at picomolar concentrations at physiological temperature[2]. The copolymer likely facilitated target-induced assembly of active MNAzyme complex. Notably, with the copolymer and the short-armed MNAzyme DNA was detected at sub-picomolar concentration at physiological temperature. Although further improvement in the sensitivity will be required to enable utility in point-of-care diagnostic devices, use of the cationic copolymer will facilitate construction of simple and accurate assays using MNAzymes.

Inter-polyelectrolyte nano-assembly induces folding and activation of functional peptides

Insufficient solubility, fragile folding structure and short half-life frequently hamper use of peptides as biological reagents or therapies. To enhance the peptide function, the effect of complexation of the peptides with ionic graft copolymers with water-soluble graft chains was tested in this study. Amphiphilic anionic peptide E5 acquires membrane disrupting activity at acidic pH due to folding from the random coil state to an ordered α-helical structure. Aggregation and imprecise folding of the peptide limited membrane disrupting activity of the peptide. In the presence of a cationic graft copolymer, E5 and its analogs adopted an ordered conformation without aggregation. The mixture of the peptides and the copolymer functioned more efficiently than peptide alone at not only acidic pH but also neutral pH at which the peptide alone had no activity. Similarly, a cationic peptide was successfully folded and activated by an anionic graft copolymer. Thus, our analysis indicated that spontaneous nano-assembly of ionic peptides with graft copolymers having opposite ionic charges triggers the folding of peptides without loss of solubility, leading to enhanced bioactivity.

Design and Characterization of Liquidlike POSS-Based Hybrid Nanomaterials Synthesized via Ionic Bonding and Their Interactions with CO2

Liquidlike nanoparticle organic hybrid materials (NOHMs) were designed and synthesized by ionic grafting of polymer chains onto nanoscale silica units called polyhedral oligomeric silsesquioxane (POSS). The properties of these POSS-based NOHMs relevant to CO2 capture, in particular thermal stability, swelling, viscosity, as well as their interactions with CO2, were investigated using thermogravimetric analyses, differential scanning calorimetry, and NMR and ATR FT-IR spectroscopies. The results indicate that POSS units significantly enhance the thermal stability of the hybrid materials, and their porous nature also contributes to the overall CO2 capture capacity of NOHMs. The viscosity of the synthesized NOHMs was comparable to those reported for ionic liquids, and rapidly decreased as the temperature increased. The sorption of CO2 in POSS-based NOHMs also reduced their viscosities. The swelling behavior of POSS-based NOHMs was similar to that of previously studied nanoparticle-based NOHMs, and this generally resulted in less volume increase in NOHMs compared to their corresponding polymers for the same amount of CO2 loading.

Liquid Crystalline Ionic Dendrimers Containing Luminescent Oxadiazole Moieties

Two novel series of dendrimers constituted by the ionic grafting of poly(propyleneimine) PPI-(NH2)x (x = 4, 8, 16, 32, 64) and poly(amidoamine) PAMAM-(NH2)x (x = 64) with carboxylic acids bearing an oxadiazole ring have been synthesized, and their liquid crystalline properties have been investigated. Series I is generated by the ionic attachment between the dendrimers and 1,3,4-oxadiazole-containing acids. Series II results from the ionic junction of the dendrimers to 1,2,4-oxadiazole-containing acids. The liquid crystalline behavior has been investigated by means of differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffractometry (XRD). The liquid crystal properties are significantly improved in the dendrimers compared to the mesogenic precursors. The structural parameters determined by X-ray diffraction reflect the different supramolecular organization built by each kind of oxadiazole-containing acid introduced. On the basis of these experimental results, a packing ...

Synthesis and characterization of well defined polysulfone-g-poly(styrenesulfonic acid) graft copolymers for proton exchange membrane

A series of amorphous graft copolymers of polysulfone-g-poly(styrenesulfonic acid) (PSF-g-PSSA) with well-defined structures was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. Graft copolymers of three different graft densities, i.e., 8, 5.5, and 3 grafts per chain, with three different degrees of polymerization (DP) of PSSA for each graft density were prepared. The obtained copolymers were transformed into proton exchange membranes, and well-separated simple two phase morphology was targeted in their hydrated states. They were characterized based on water uptake, ion exchange capacity (IEC), proton conductivity, and thermal sta- bility. Water uptake increased as the wt% of the ionic graft or IEC increased. For a similar value of IEC, the water uptake for the graft copolymer decreased with higher graft density. The proton conductivities of the graft membranes were in the range of 2.1×10 -3 to 1.36×10 -1 S/cm. Proton conductivity increased as the IEC increased. However, when the wt% of PSSA was lower than 20%, very low proton conductivities were observed.

Nanostructure, Morphology, and Properties of Fluorous Copolymers Bearing Ionic Grafts

In order to probe the effects of polymer microstructure on the properties of proton conducting polymer membranes, three series of fluorous−ionic graft copolymers, partially sulfonated poly([vinylidene difluoride-co-chlorotrifluoroethylene]-g-styrene) [P(VDF-co-CTFE)-g-SPS], comprising controlled graft lengths and degrees of sulfonation were synthesized. The parent building block was a poly(vinylidene difluoride-co-chlorotrifluoroethylene) [P(VDF-co-CTFE)] macroinitiator (Mn = 3.12 × 105 g/mol) synthesized to contain 1 chloro group per 17 repeat units, onto which polystyrene, having degrees of polymerization of 35, 88, and 154 units per graft, was grown by atom transfer radical polymerization (ATRP). These graft copolymers, termed short, medium, and long graft chains, were sulfonated to different extents to provide a series of polymers with varying ion exchange capacity (IEC). The resulting P(VDF-co-CTFE)-g-SPS copolymers were cast into proton exchange membranes, and their nanostructure, morphology, and pr...

Solid Polymer Electrolytes Based on Ionic Graft Polymers: Effect of Graft Chain Length on Nano-Structured, Ionic Networks

The length of graft chains in graft polymers is controlled in order to dictate the formation of a nanochannel network of ions in a non-ionic matrix. Graft polymers were prepared by copolymerization of styrene with poly(sodium styrene sulfonate) (PSSNa) macromonomers. The latter were prepared with controlled molecular weight and narrow polydispersity by stable free radical polymerization. Phase separation of ionic aggregates occurs to a greater extent in films prepared from amphiphilic polymers possessing longer graft chains. Films prepared from polymers containing low ion content comprise of isolated ionic domains and exhibit low ionic conductivity. Increasing the ion content with the membrane, by increasing the number density of ionic graft chains in the polymer, results in ionic domains that coalesce into a network of nanochannels, and a dramatic increase in ion conductivity is observed. The ionic network is developed to a greater extent for films based on longer ionic graft chain polymers; an observation explained on the basis of phase separation.

Morphologically Controlled Proton-Conducting Membranes Using Graft Polymers Possessing Block Copolymer Graft Chains

Ionic graft membranes comprising macromonomeric poly(styrene-block-styrene sulfonic acid) grafted polystyrene [PS-g-mac(PS-b-PSSA)] polymers were prepared by copolymerization of styrene and poly(styrene-block-sodium styrene sulfonate) (PS-b-PSSNa) macromonomers followed by ion-exchange. The latter were prepared with controlled molecular weight by stable free radical polymerization. Membranes exhibit varying degrees of phase separation. Membranes of low ion content are comprised of isolated ionic domains and exhibit low ionic conductivity. Increasing the number density of ionic graft chains in the polymer results in a network of nanochannels and a dramatic increase in ion conductivity. In comparison to analogous macromonomeric poly(styrene sulfonic acid) grafted polystyrene (PS-g-macPSSA) membranes, of similar ion exchange capacity (IEC) and PSSA chain length, dehydrated PS-g-mac(PS-b-PSSA) membranes consist of smaller, more densely connected ionic domains; however, water sorption and ionic conductivity are similar.

Synthesis of a new microphase‐separated polymer system by “counterion coupling” and its X‐ray characterization

AbstractA new type of highly ordered, microphase‐separated polymer material is synthesized by simple ionic coupling of a commercial styrene/ethylene oxide twoblock copolymer with a charged end group to an oppositely charged polyelectrolyte by common precipitation from aqueous solution. The characterization of the polymer/polymer complex by small‐angle X‐ray scattering and polarization microscopy reveals that the comb‐like addition complexes formed by ionic grafting build up a mesophase with lamellar morphology and a periodicity of d = 7.1 nm which is easily oriented in mechanic fields.

Cationic Graft Polymerization of 2-Oxazolines on Poly(vinyl alcohol) Derivatives

Abstract The graft polymerization of various monomers onto PVA has been studied by radical polymerization mechanism. Successful grafting of acrylonitrile (AN), acrylamide (AAm), acrylic acid, methyl methacrylate, and vinyl acetate was reported by using chemical (Minoet al., 1959; Ide, 1961; Maskimov et al., 1965) and radiation (Misra et al., 1987) methods. On the other hand, less attention has been paid to ionic graft polymerization. Sasson and Zilkha reported on grafting formaldehyde onto potassium-metallated PVA (Sasson and Zilkha, 1969). Galin studied grafting of AN and propane sulfone onto sodium-metallated PVA (Galin, 1971). We used the same anionic system for the polymerization of AAm (Ikeda and Suzuki, 1980).

Radiation-grafted membranes for pervaporation of ethanol/water mixtures

The pervaporation properties of graft copolymer membranes with poly(vinylidene fluoride) (PVF 2), poly(vinyl fluoride) (PVF), poly(hexafluoropropene-co-tetrafluoroethene) (FEP), and polyacrylonitrile (PAN) as trunk materials have been investigated. Various monomers which yield polar, basic, acidic and ionic functional groups have been grafted by means of the preirradiation technique using 160 keV electrons from an accelerator. The purpose was to elucidate the influence of membrane-permeant interactions on the pervaporation of ethanol/water mixtures. Most of the graft membranes exhibit high fluxes of 0.5-3.0 kg-m −2-hr −1 in pervaporation experiments at 343 K with 80% ethanol in the feed solution. Non-ionic membranes exhibit moderate separation factors (α H2O = 2-15) while ionic graft chains lead to very low ethanol concentrations in the permeate, corresponding to α H2O up to 1000. The dependence of pervaporation on the grafting yield, the feed concentration, the temperature and, in the case of ion exchange membranes, the kind of counterion and trunk polymer has been worked out for different grafting systems. The membrane properties have been correlated to the morphology of the grafted films.

Radiation-induced ionic graft polymerization

Radiation-induced ionic graft polymerization