Grafting Of Acrylic Acid Research Articles

Sonochemical synthesis and characterization of emulsion polymer for sorption of lanthanides

Recent advances in nanostructure materials have been developed by new synthetic method that provides control over size and chemical structure. The utilization of high intensity ultrasound has been investigated for synthesis of nanostructure polymer that is often unavailable by conventional methods. The preparation of emulsion polymer of carboxy methyl cellulose (CMC) as a backbone with grafting of methyl acrylate and acrylic acid has been investigated using ultrasonic irradiation at 15min and Tween 80 as a surfactant which, hardly formed by conventional co-polymerization methods. Tween 80 was immersed inside the polymer matrix to improve interfacial tension between polymer and outer sphere water molecule, as well as to overcome the aggregation and compact of the component inside the polymer which, facilitate the grafting reaction. The influence of surfactant type, ultrasonic time and temperature on the particle morphology was studied. Moreover, Nitrilo tri-acetic acid (NTA) was grafted during the polymerization process to increase the effective function groups and hence increasing the sorption capacity toward Lanthanum (La3+), Cerium (Ce3+), Neodymium (Nd3+), Gadolinum (Gd3+) and Uranium (U4+) metal ions. The results showed relatively high sorption capacity reached to110, 121,169, 131, 158, 198 for La3+, Ce3+, Nd3+, Eu3+, Gd3+ and U4+ mg/g metal ions respectively.

Design of psyllium-g-poly(acrylic acid-co-sodium acrylate)/cloisite 10A semi-IPN nanocomposite hydrogel and its mechanical, rheological and controlled drug release behaviour

Soft biomaterials derived from polysaccharides are generally suffers from lack of mechanical robustness and instability. The naturally occurring highly abundance low cost polysaccharide has immense aspect as biomaterial after functionalization which can be designed as stretchable and rubber-like elastic with reversible ductility. A highly swellable, stretchable, low creep, non-cytotoxic nanocomposite hydrogel has been fabricated by simple one-pot Michael type covalent grafting of acrylic acid based copolymer onto psyllium biomacromolecular chian by free radical gelation technique. The fabricated hydrogel was rheologically tested which implies its viscoelastic and thixotropic like features. The porous morphology of the hydrogel was confirmed by scanning electron micrograph. The cryo-transmission electron micrograph shows the random dispersion of the nanoclay (cloisite 10A) tactoids in exfoliated as well intercalated forms. These random distributions of clay nanosheets also enhance the mechanical toughness and reversible ductility of the hydrogels which was also supported by the mechanical and loading-unloading cycle measurement. Nonetheless, the nanocomposite hydrogel was non-cytotoxic against human cell-line (human osteosarcoma) and shows good cell attachment of live cells in a 5-day ‘live-dead’ assay with almost negligible quantity of cell death. These attributes can promote this material as a soft biomaterial for controlled release device with mechanical robustness and rubber-like elasticity.

A synthesis and performance evaluation of a highly efficient ecological dust depressor based on the sodium lignosulfonate-acrylic acid graft copolymer.

In this paper, a highly efficient and environmentally-friendly dust depressor was developed based on the sodium lignosulfonate–acrylic acid graft copolymer. Using the grafting ratio as an index, a three-factor and four-level orthogonal experiment was conducted to optimize the fabrication conditions of the graft copolymer. At a reaction temperature of 60 °C, feed ratio mSLS–AA of 1 : 3, and FeSO4·7H2O content of 2.5%, the prototype produced the highest grafting ratio. The microstructure of the graft copolymer was measured using Fourier transform infrared spectrometry (FTIR) and nuclear magnetic resonance (1H-NMR). Furthermore, the influence of glycerol and the JFC penetrant on the contact angle between the compound solution and coal powder was investigated. Finally, four formulas of dust depressor were selected based on the experimental results. The dust-control performance of the four dust depressors was then tested on a large-scale spray dust suppression simulation platform. The results show that after applying formula 1 at various distances from the spray field, the average dust reduction rates of the total dust (respirable dust) at each point increased. Compared to the water-spraying dust suppression technique, the dust concentration is significantly reduced after the graft copolymer dust depressor is applied.

Electron-beam-induced post-grafting polymerization of acrylic acid onto the surface of Kevlar fibers

The surface of Kevlar fibers was successfully modified by electron beam (EB)-induced post-grafting of acrylic acid (AA). The generation of radicals in the fibers was confirmed by electron spin resonance (ESR) measurements, and the concentration of radicals was shown to increase as the absorbed dose increased, but decrease with increasing temperature. The influence of the synthesis conditions on the degree of grafting was also investigated. The surface microstructure and chemical composition of the modified Kevlar fibers were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The SEM images revealed that the surface of the grafted fibers was rougher than those of the pristine and irradiated fibers. XPS analysis confirmed an increase in C(O)OH groups on the surface of the Kevlar fibers, suggesting successful grafting of AA. These results indicate that EB-induced post-grafting polymerization is effective for modifying the surface properties of Kevlar fibers.

A comparative study of polyethylene terephthalate surface carboxylation techniques: Characterization, in vitro haemocompatibility and endothelialization

Surface functionalization of polymers is crucial for improving biocompatibility and haemocompatibility, which correlates to improved performance of medical devices. Here, we have evaluated the effect of four PET surface carboxylation techniques on the antifouling property, haemocompatibility, and endothelialization. Surface carboxylation was achieved by formaldehyde+bromoacetic acid treatment (PET-1[COOH]), methacrylic acid grafting (PET-2[COOH]), NaOH hydrolysis+KMnO4 oxidation (PET-3[COOH]), and oxygen plasma treatment+acrylic acid grafting (PET-4[COOH]). The carboxyl densities on these surfaces were 0.4, 23.2, 31.9, 16.4nmol/cm2, respectively. XPS and FTIR spectroscopy confirmed the introduction of carboxyl groups. Water contact angle results showed that hydrophilicity increased with an increase in surface carboxyl density. SEM images confirmed that these modifications didn't cause any surface deterioration. AFM studies showed an increase in surface roughness of the carboxylated PET. Tensile testing showed that these modifications did not affect the bulk properties. Compared to control, PET-3[COOH] has a 9-fold reduction in BSA adsorption. Haemocompatibility studies showed significantly reduced %hemolysis and platelet adhesion on the carboxylated PET. Cell culture studies revealed that endothelial cell (EA.hy926) attachment increased with increase in surface carboxyl density. PET-3[COOH] showed the most improved haemocompatibility and endothelial cell attachment. These results clearly show that the method of functionalization has a significant impact on the haemocompatibility and cell attachment.

Acrylated Composite Hydrogel Preparation and Adsorption Kinetics of Methylene Blue.

By using cyclodextrin (α-CD) self-assembly into a hydrogel with the triblock copolymer Pluronic F127, nanomicrocrystalline cellulose was introduced into a gel system to form a composite CNC-β-CD/α-CD/Pluronic F127 hydrogel (CCH). CCH was modified further by grafting acrylic acid to form a novel acrylated composite hydrogel (ACH). The swelling degree of ACH was 156 g/g. Adsorption isotherms show that the adsorption process for methylene blue proximity fitted the Freundlich model. The adsorption kinetics showed that ACH followed a quasi-second-order kinetic model. Methylene blue desorption showed that ACH was a temperature- and pH-dependent gel. Repeated adsorption and desorption experiments were carried out three times, and the removal rate of methylene blue at 75 mg/L was still 70.1%.

Light induced growth of polyelectrolyte brushes on kaolinite surface with superior performance for capturing valuable rare-earth Ce3+ from wastewater

In order to obtain a low-cost and effective adsorbent for separating valuable rare-earth ions from wastewater, a surface rich carboxyl decorated kaolinite composite (PAA-KLN) was fabricated through poly(acrylic acid) grafting via an integrated UV-initiated grafting approach, involving surface hydrophobic modification under ordinary temperature and the coating of liquid photosensitizer (benzophenone) film to meet the specific initiator/substrate combination. The successful grafting was characterized by XRD, SEM/TEM, FTIR and TG/DTG/DSC. Due to the good hydrophilic property of poly(acrylic acid) brushes, their free-end would extend into the solution to form a surface villus layer, bringing lots of highly accessible adsorption sites. The resultant PAA-KLN exhibited outstanding adsorption capacity for Ce3+ of 189.63 mg/g and rapid adsorption rate (reaching equilibrium within 40 min). Furthermore, PAA-KLN displayed an excellent reusability with high desorption ratio even at low concentration stripping liquid (0.2 M HCl), demonstrating its excellent application potential in recycling valuable metal from wastewater.

Plasma-induced grafting of acrylic acid on bentonite for the removal of U(VI) from aqueous solution

Fabrication of reusable adsorbents with satisfactory adsorption capacity and using environment-friendly preparation processes is required for the environment-related applications. In this study, acrylic acid (AA) was grafted onto bentonite (BT) to generate an AA-graft-BT (AA-g-BT) composite using a plasma-induced grafting technique considered to be an environment-friendly method. The as-prepared composite was characterized by scanning electron microscopy, x-ray powder diffraction, thermal gravity analysis, Fourier transform infrared spectroscopy and Barrett–Emmett–Teller analysis, demonstrating the successful grafting of AA onto BT. In addition, the removal of uranium(VI) (U(VI)) from contaminated aqueous solutions was examined using the as-prepared composite. The influencing factors, including contact time, pH value, ionic strength, temperature, and initial concentration, for the removal of U(VI) were investigated by batch experiments. The experimental process fitted best with the pseudo-second-order kinetic and the Langmuir models. Moreover, thermodynamic investigation revealed a spontaneous and endothermic process. Compared with previous adsorbents, AA-g-BT has potential practical applications in treating U(VI)-contaminated solutions.

Proton-conducting polymers derived from radiation grafting and sulphonation of poly(tetraflouroethylene-perflourovinyl ether) film with three rare-earth elements

Progress in the area of proton conducting polymer electrolyte membranes is closely with the enhancing of polymer electrolyte membrane fuel cells. Fluorinated polymers, e.g. poly(tetraflouroethylene-perflourovinyl ether) (PFA) film is largely driven by their thermal properties. In this article PFA film was developments to be suitable as proton conducting polymer electrolyte membranes. The grafting of acrylic acid (80%) onto the PFA film achieved by irradiation techniques and PFA-COOH was obtained. In addition, to synthesis of completely a new protonconducting sulfonated polymer ionomers this could be acheived by sequences of chemical modification steps. PFA-COOH has been anilination and sulfonated to a sufficient ionomers formation and complexion with the three rare-earth elements (Li, Cs, and Sr). After that the obtained PFA-CO-NH-ph-SO3M contains a sufficient equilibrium concentration of protons in a wet atmosphere to show useful proton conduction at ambient temperatures. The sulfonated polymers containing 63 mol% sulfonic acid, and characterized by FTIR-ATR and SEM The results show that PFACO-NH-ph-SO3M wet film showed a high proton-conductivity in water (10-3 Scm-1) rather than methanol (10-6 Scm-1) in order Li+> Sr++>Cs+. This approach has interesting potential for smart thin film materials and offers also the possibility to be used in sensors and fuel cells provided that the electrolyte film thickness is in the micrometre range.

Evaluation of the CFRP grafting and its influence on the laser joining CFRP to aluminum alloy

In the case of laser direct joining carbon fiber reinforced plastic (CFRP) to A6061 aluminum alloy, the strength of the dissimilar joint is low. The UV grafting of acrylic acid was proposed to modify the CFRP surface before the laser joining process. The result showed that the shear strength of the joint could be enhanced from 5.3 to 30.1 MPa when optimized parameters (irradiation distance: 10 mm; irradiation time: 30 s) of UV grafting were applied. X-ray photoelectron spectroscopy and scanning electron microscope were applied to study the surface characteristic of grafted CFRP and the strengthening mechanism of the grafting modification. The C=O bond and O–C=O bond on the CFRP increased after the modification with UV grafting. It could be figured out that new chemical bonds, including Al–C and Al–O–C, were produced between Al and the matrix resin of the CFRP and it played a key role in improving the strength of grafted CFRP/A6061 dissimilar joint. Thus, as a high-efficient and effective technique, UV grafting is a promising method to improve the laser joining CFRP to aluminum.

Modified Nylon Fibers with Amino Chelating Groups for Heavy Metal Removal

Abstract: This study reports a feasible method for heavy metal ions removal from aqueous via modified nylon fibers. Modified nylon fibers were used as sorbent materials in batch experiment. The amine/amide groups on nylon fibers’ surface were modifies by acrylic acid graft copolymerization and ethylenediamine solution. Surface modification was observed to enhanced the sorption capacity of nylon fibers by more than about 90% and 20% for Pb(II) and Cr(IV) removal, respectively. These caused of ability of the amine/amide chelating groups on the fiber. The experiments also investigated the influencing of pH, initial concentration, and contact time. The adsorption mechanisms of Pb(II) and Cr(IV) were following Freundlich’s isotherm and pseudo second-order reaction.

Efficient Removal of Methylene Blue Using a Hybrid Organic–Inorganic Hydrogel Nanocomposite Adsorbent Based on Sodium Alginate–Silicone Dioxide

In this work, we reported synthesis, structure characterization and methylene blue (MB) adsorption of a novel organic–inorganic hydrogel nanocomposite adsorbent (HNA) based on sodium alginate (NaAlg) and silicone dioxide nanoparticles (SiO2-NPs). The HNAs were prepared using grafting of acrylic acid (AA) onto NaAlg by using ammonium persulfate as a free radical initiator and methylene bisacrylamide as a crosslinker in the presence of SiO2-NPs, which synthesized in situ from the base-catalyzed hydrolysis of tetraethylorthosilicate (TEOS). The structure of HNAs were characterized by FTIR, SEM, EDX, TEM, XRD, UV–Vis and TGA techniques and a proposed mechanism for preparation of adsorbents was also suggested. The swelling capacity of HNAs was examined in buffer solutions with pH ranged 1.0–14.0. The nanocomposites exhibited a pH-responsiveness character so that a swelling-deswelling pulsatile behavior was recorded at pHs 2.0 and 9.0. The swelling kinetics of HNA was also preliminary investigated. Moreover, the effects of agitation time, pH, initial dye concentration, adsorbent dose, TEOS content, AA concentration and temperature were optimized with respect to dye adsorption capacity of HNAs in detail. Furthermore, the kinetic and adsorption isotherm of MB dye onto HNAs were investigated in detail. The HNAs also showed excellent regeneration capacity after five consecutive cycles of dye adsorption–desorption. In general, the results indicated that the synthesized adsorbents with biodegradability and biocompability properties can be used in wastewater treatment via dye adsorption.

Fast and high-capacity adsorption of Rb+ and Cs+ onto recyclable magnetic porous spheres

A novel recyclable magnetic porous sphere adsorbent is prepared by grafting acrylic acid (AA) onto hydroxypropyl cellulose (HPC) through a Pickering emulsion integrated precipitation polymerization and used for the enrichment of scattered strategic metals Rb+ and Cs+. The modified Fe3O4 nanoparticles can not only stabilize the Pickering emulsion template for forming pores, but also make the adsorbent easy to be separated from solution by magnetic field. The adsorption results indicate that the adsorption of Rb+ and Cs+ by the sphere adsorbent rapidly reaches equilibrium within 15 and 30min, respectively. The saturated adsorption capacities reach 310 and 448mg/g for Rb+ and Cs+, respectively, which are better than that reported in most of literatures. Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses confirm that the chemical complexation of –COO− and –OH with Rb+ and Cs+ contribute mainly to the adsorption. In addition, the adsorbent is very easy to be recovered and regenerated, and the adsorption capacity does not decrease significantly even after five consecutive adsorption–desorption cycles, as compared with the initial adsorption capacity. The results of dynamic adsorption experiments show that the flow rate, initial ion concentration and column height have an effect on the adsorption capacities of Rb+ or Cs+. In a word, this recyclable sphere adsorbent is promising to be used for the efficient adsorption and enrichment of rare metals.

Fabrication of reverse‐osmosis membranes for the desalination of underground water via the γ‐radiation grafting of acrylic acid onto polyethylene films

ABSTRACTResearch has been devoted to the desalination of saline water to fresh water suitable for human demands because of the shortage of water in some countries. Therefore, in this study, reverse‐osmosis membranes were prepared via the γ‐radiation graft copolymerization of acrylic acid onto high‐density and low‐density polyethylene. The factors that could affect the grafting process, such as the solvent type, monomer and inhibitor concentration, and irradiation dose, were investigated to determine the optimum conditions for radiation grafting. The polyethylene grafted acrylic acid copolymers (PAAc‐g‐PE) graft copolymer was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical, rheological, and thermal property testing to illustrate the possibility of practical use in water desalination. The prepared grafted membranes showed significant results in the reverse‐osmosis desalination method with underground saline water. The factors affecting the desalination of water, such as the water flux, operation time, and grafting percentage, were studied. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45410.

In vitro mineralization of dual grafted polytetrafluoroethylene membranes.

The modification of biomaterials by radiation induced grafting is a promising method to improve their bioactivity. Successful introduction of carboxyl and amine functional groups on the surface of a polytetrafluoroethylene membrane was achieved by grafting of acrylic acid (AA) and 2-aminoethyl methacrylate hydrochloride (AEMA) using simultaneous gamma irradiation grafting. Chemical characterization by attenuated total reflectance Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy confirmed the presence of amine and carboxylate functionalities and indicated that all protonated amines formed ion pairs with carboxyl groups, but not all carboxyl are involved in ion pairing. It was found that the irradiation doses (2, 5, or 10 kGy) affected the grafting outcome only when sulfuric acid (0.5 or 0.9 M) was added as a polymerization enhancer. The use of the inorganic acid successfully enhanced the total graft yield (GY), but the changes in the graft extent (GE) were not conclusive. Dual functional films were produced by either a one- or a two-step process. Generally, higher GY and GE values were observed for the samples produced by the two-step grafting of AA and AEMA. The in vitro mineralization in 1.5× simulated body fluid (SBF) induced the formation of carbonated hydroxyapatite as verified by FITR. All samples showed an increase in weight after mineralization with significantly larger increases observed for the samples which had the 1.5× SBF changed every third day compared to every seventh. For the dual functional samples, it was found that the sample grafted by the one-step method shows a significantly higher increase in weight despite a much lower GY compared to the sample prepared by the two-step method and this was attributed to the different architecture of grafted chains.

Surface modification of polyamide TFC membranes via redox‐initiated graft polymerization of acrylic acid

ABSTRACTIn this work, the redox‐initiated graft polymerization of acrylic acid (AA) onto the surface of polyamide thin film composite membranes has been carried out to enhance membrane separation and antifouling properties. The membrane surface characteristics were determined through the attenuated total reflection Fourier transform infrared spectra, scanning electron microscopy, atomic force microscopy, and water contact angles. The membrane separation performance was evaluated through membrane flux and rejection of some organic compounds such as reactive red dye (RR261), humic acid, and bovine serum albumin in aqueous feed solutions. The experimental results indicated that the membrane surfaces became more hydrophilic and smoother after grafting of AA. The modified membranes have a better separation performance with a significant enhancement of flux at a great retention. The fouling resistance of the modified membranes is also clearly improved with the higher maintained flux ratio and the lower irreversible fouling factor compared to the unmodified one. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45110.

Superiorly Plasticized PVC/PBSA Blends through Crotonic and Acrylic Acid Functionalization of PVC.

Superior plasticization efficiency was achieved by a grafting from functionalization of the PVC backbone. This was deduced to a synergistic effect of internal plasticization and improved intermolecular interactions between PVC and an oligomeric poly(butylene succinate-co-adipate) (PBSA) plasticizer. A mild grafting process for functionalization of the PVC chain by crotonic acid (CA) or acrylic acid (AA) was used. The formation of PVC-g-CA and PVC-g-AA was confirmed by FTIR and 1H NMR. Grafting with the seemingly similar monomers, CA and AA, resulted in different macromolecular structures. AA is easily homopolymerized and long hydrophilic poly(acrylic acid) grafts are formed resulting in branched materials. Crotonic acid does not easily homopolymerize; instead, single crotonic acid units are located along the PVC chain, leading to basically linear PVC chains with pendant crotonic acid groups. The elongation of PVC-g-CA and PVC-g-AA in comparison to pure PVC were greatly increased from 6% to 128% and 167%, respectively, by the grafting reactions. Blending 20% (w/w) PBSA with PVC, PVC-AA or PVC-CA further increased the elongation at break to 150%, 240% and 320%, respectively, clearly showing a significant synergistic effect in the blends with functionalized PVC. This is a clearly promising milestone towards environmentally friendly flexible PVC materials.

Amidoxime-based adsorbents prepared by cografting acrylic acid with acrylonitrile onto HDPE fiber for the recovery of uranium from seawater

An amidoxime-based polymeric adsorbent was prepared by pre-irradiation grafting of acrylonitrile and acrylic acid onto high-density polyethylene fibers using electron beams, followed by amidoximation. Quantitative recovery of uranium was investigated by flow-through experiment using simulated seawater and marine test in natural seawater. The maximum amount of uranium uptake was 2.51 mg/g-ads after 42 days of contact with simulated seawater and 0.13 mg/g-ads for 15 days of contact with natural seawater. A lower uranium uptake in marine test can be attributed to the short adsorption time and the contamination of marine microorganisms and iron. However, the high selectivity toward uranium against vanadium may be beneficial to harvest uranyl ion onto adsorbents and the economic feasibility for recovery of uranium from seawater.

Tetra-Sensitive Graft Copolymer Gels as Active Material of Chemomechanical Valves.

Stimuli-responsive hydrogels combine sensor and actuator properties by converting an environmental stimulus into mechanical work. Those materials are highly interesting for applications as a chemomechanical valve in microsystem technologies. However, studies about key characteristics of hydrogels for this application are comparatively rare, and further research is needed to emphasize their real potential. The first part of this study depicts the synthesis of grafted hydrogels based on a poly(N-isopropylacrylamide) backbone and pH-sensitive poly(acrylic acid) graft chains. The chosen approach of grafted hydrogels provides the preparation of multiresponsive hydrogels, which retain temperature sensitivity besides being pH-responsive. A pronounced salt and solvent response is additionally achieved. Key characteristics for an application as a chemomechanical valve of the graft hydrogels are revealed: (1) independently addressable response to all stimuli, (2) significant volume change, (3) sharp transition, (4) reversible swelling-shrinking behavior, and (5) accelerated response time. To prove the concept of multiresponsive hydrogels for flow control, a net-poly(N-acrylamide)-g-poly(acrylic acid) hydrogel containing 0.6 mol % poly(acrylic acid)-vinyl is employed as active material for chemomechanical valves. Remarkably, the chemomechanical valve can be opened and closed in a fluidic platform with four different stimuli.

Modification of UHMWPE porous fibers by acrylic acid and its adsorption kinetics for Cu2+ removal

Polyacrylic acid-grafted ultrahigh molecular weight polyethylene (UHMWPE-g-PAA) fibers were prepared by radiation-induced grafting of acrylic acid onto UHMWPE porous fibers and were examined for Cu2+ removal from aqueous solutions. The developed fibers were characterized using Fourier transform infrared spectroscopy, mechanics test, scanning electron microscopy and energetic dispersive spectroscopy analysis. It was demonstrated that the UHMWPE fibers were modified successfully with grafted acrylic acid, which conferred excellent hydrophilic performance to UHMWPE porous fibers. The mechanics test indicated that considerable mechanical strength (~0.4 GPa) still reserved for the UHMWPE-g-PAA fibers in spite of somewhat radiation degradation. The high-strength, hydrophilic and porous natures render UHMWPE-g-PAA fibers promising as economical adsorbent in wastewater treatment. Prepared under different radiation dose and different degree of grafting of polyacrylic acid (PAA), the adsorption kinetics of the UHMWPE-g-PAA fibers was investigated using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The results reveal a large adsorption capacity of 63 mg g−1 for the UHMWPE-g-PAA fibers and the adsorption behavior follows perfectly a pseudo-second-order kinetics model regarding the Cu2+ solution adsorption.