The studies on the stimuli‐response of poly (N,N‐dimethylamino ethyl methacrylate/acrylic acid‐co‐acrylamide) complex hydrogel under DC electric field

A polyelectrolyte complex hydrogel, poly (N,N‐dimethylaminoethyl methacrylate/acrylic acid‐co‐acrylamide) hydrogel designed as PDMEAA, was prepared by the free radical copolymerization in aqueous solutions. Without chemical crosslinker, PDMEAA hydrogel network was formed by electrostatic attraction of the proton‐transfer between acrylic acid and N,N‐dimethylamino ethyl methacrylate. Since the electrostatic attraction could be weakened by the application of electric field, PDMEAA hydrogel was decomposed under contacted electric field. Various factors such as gel composition, the species and concentration of electrolytes, voltage, and the experimental set‐ups, could effect the decomposing process of PDMEAA hydrogel. In CaCl₂ and MgCl₂ solutions, PDMEAA hydrogel had no change under electric field. And in high concentration of NaCl and Na₂SO₄ solutions, PDMEAA hydrogel has been eroded linearly with the increasing time applied electric field. In low concentration of NaCl and Na₂SO₄ solutions, however, a swelling process was found before the erosion. The stimuli‐responsive mechanism was investigated through scanning electron microscope (SEM) and gel permeation chromatography (GPC). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and properties of poly(sodium acrylate‐co‐2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid)/attapulgite as a salt‐resistant superabsorbent composite

A novel salt‐resistant superabsorbent composite was prepared by copolymerization of partially neutralized acrylic acid, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid (AMPS) and attapulgite (APT). To enhance the swelling rate (SR) of the copolymer, sodium bicarbonate was used as a foaming agent in the course of copolymerization. Furthermore, for improving the properties of swollen hydrogel, such as strength, resilience and dispersion, the copolymer was surface‐crosslinked with glycerine and sodium silicate, and then the surface‐crosslinked copolymer was blended with aluminum sulfate and sodium carbonate in post treatment process. The influences of some reaction conditions, such as amount of AMPS, APT, and initiator, and neutralization degree of acrylic acid on water absorbency in 0.9 wt% NaCl aqueous solution both under atmospheric pressure (WA) and load (WA_P, P ≈ 2 × 10³ Pa) were investigated. In addition, the effect of them on SR was also studied. The WA and WA_P of the superabsorbent composite prepared under optimal conditions in 0.9 wt% NaCl aqueous solution were 52 g·g^?1 and 8 g·g^?1, respectively. Besides, the SR was fast, and it could reach 0.393 mL·(g·s)^?1. Moreover, the swollen hydrogel possessed excellent salt resistance, hydrogel resilience and dispersion. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Preparation of ‘click’ hydrogels from polyaspartamide derivatives

Lately, copper‐assisted azide–alkyne cycloaddition (CuAAC) has become a very interesting tool for synthesizing biocompatible polymer‐based materials such as hydrogels or microgels, which can be used as biomaterials for tissue engineering and drug delivery. Novel poly(2‐hydroxyethyl aspartamide)s (PHEAs) functionalized with pendent acetylene or azide groups were prepared from polysuccinimide, which is the thermal polycondensation product of aspartic acid, through successful ring‐opening reactions using propargylamine, 1‐azido‐2‐aminoethane and ethanolamine. The composition of the prepared copolymers was analyzed using ¹H NMR spectroscopy. Clickable PHEA derivatives were crosslinked by mixing together in water with a catalyst system of Cu(I) and N, N, N′, N′, N″‐pentamethyldiethylenetriamine, a type of Huisgen's 1,3‐dipolar azide‐alkyne cycloaddition. The reaction of the polymers resulted in a chemoselective coupling between alkynyl and azido functional groups with multiple formation of triazole crosslinks to give hydrogels. The triazole linkages in the hydrogels are highly stable and may also play a role in swelling behavior. PHEA‐based hydrogels were also obtained by the crosslinking of azide‐ or alkyne‐modified PHEA with a small‐molecule crosslinker. The hydrogels prepared using these two methods were characterized by their degree of swelling and the morphology of the hydrogels was confirmed using scanning electron microscopy. The approach we describe here presents a promising alternative to common chemical hydrogel preparation techniques, and these hydrogels seem to possess structures having potential for a variety of industrial and biomedical applications. © 2012 Society of Chemical Industry     

Synthesis of pH‐responsive crosslinked poly[styrene‐co‐(maleic sodium anhydride)] and cellulose composite hydrogel nanofibers by electrospinning

BACKGROUND: Stimuli‐sensitive materials show enormous potential in the development of drug delivery systems. But the low response rate of most stimuli‐sensitive materials limits their wider application. We propose that electrospinning, a technique for the preparation of ultrafine fibrous materials with ultrafine diameters, may be used to prepare materials with a fast response to stimuli. RESULTS: Poly[styrene‐co‐(maleic sodium anhydride)] and cellulose (SMA‐Na/cellulose) hydrogel nanofibers were prepared through hydrolysis of precursor electrospun poly[styrene‐co‐(maleic anhydride)]/cellulose acetate (SMA/CA) nanofibers. In the presence of diethylene glycol, the SMA/CA composite nanofibers were crosslinked by esterification at 145 °C, and then hydrolyzed to yield crosslinked SMA‐Na/cellulose hydrogel nanofibers. These nanofibers showed better mechanical strengths and were pH responsive. Their water swelling ratio showed a characteristic two‐step increase at pH = 5.0 and 8.2, with the water swelling ratio reaching a maximum of 27.6 g g^?1 at pH = 9.1. CONCLUSION: The crosslinked SMA‐Na hydrogel nanofibers supported on cellulose showed improved dimensional stability upon immersion in aqueous solutions. They were pH responsive. This new type of hydrogel nanofiber is a potential material for biomedical applications. Copyright © 2009 Society of Chemical Industry     

Multi‐responsive hydrogels based on N‐isopropylacrylamide and sodium alginate

Hydrogels consisting of sodium alginate and N‐isopropylacrylamide covalently crosslinked with N,N′‐methylenebisacrylamide were prepared. The mixed‐interpenetrated networks obtained were characterized using elemental analysis, Fourier transform infrared and Raman spectroscopy, swelling measurements and environmental scanning electron microscopy. The thermo‐ and pH‐responsive properties of these hydrogels were evidenced by their swelling behaviour, which depended also on the amount of crosslinking agent and hydrogel composition. Copyright © 2010 Society of Chemical Industry     

Radiation synthesis and application of a hydrogel based on acrylic acid and 2‐mercaptobenzimidazole

A hydrogel based on gamma‐radiation polymerization of acrylic acid (AAc) in the presence of 2‐mercaptobenzimidazole (MBI) and a crosslinking agent was prepared. The properties of this AAc/MBI hydrogel were characterized in terms of gel content, swelling in different solvents, structure morphology, and IR spectroscopy. Moreover, the thermal decomposition behavior of the prepared hydrogel was investigated by thermogravimetric analysis (TGA). The TGA thermograms were also used to determine the different kinetic parameters such as order of reaction and activation energy. The sorption of some divalent metal ions such as Cu²⁺, Pb²⁺, Cd²⁺, and Hg²⁺ by the AAc/MBI hydrogel also was studied. The results showed that the AAc/MBI hydrogel has a higher tendency to swell in water and polar solvents than in nonpolar solvents. The highest metal uptake by the hydrogel was found for Hg²⁺ and Cd²⁺, whereas the lowest was for Cu²⁺ and Pb²⁺ ions. The ratios between the distribution coefficients of the different metals [separation factors (SF)] indicate that the hydrogel has a high selectivity for Hg²⁺ over Cu²⁺ (SF = 10.923) and Pb²⁺ (SF = 19.110). However, the hydrogel prefers Hg²⁺ over Cd²⁺ (SF = 1.356) and showed a high selectivity for Cd²⁺ over Cu²⁺ (SF = 7.822) and Pb²⁺ (SF = 7.240). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1607–1614, 2002     

Crosslinking of addition copolymers from tricyclononenes bearing (CH3)3Si‐ and (C2H5O)3Si‐groups as a modification of membrane gas separation materials

Here, we report the synthesis and the study of gas‐transport properties of crosslinked highly permeable copolymers from Si‐containing norbornene derivatives. The initial high‐molecular‐weight copolymers were prepared via addition copolymerization of 3‐trimethylsilyltricyclo[4.2.1.0^2,5]non‐7‐ene (TCNSi1) with 3‐triethoxysilyltricyclo[4.2.1.0^2,5]non‐7‐ene (TCNSiOEt) in good or high yields using a Pd‐catalyst. The obtained copolymers included up to 10 mol% of TCNSiOEt units bearing reactive Si–O–C‐containing substituents. The crosslinking was readily realized by using simple sol–gel chemistry in the presence of Sn‐catalyst. The formed crosslinked copolymers were insoluble in common organic solvents. Permeability coefficients of various gases (He, H₂, O₂, N₂, CO₂, CH₄, C₂H₆, C₃H₈, n‐C₄H₁₀) in these copolymers before and after crosslinking were determined and the influence of the incorporated TCNSiOEt units as well as the crosslinking on gas transport properties were established. As a result, it was found that only a small reduction of gas‐permeability was observed when TNCSiOEt units were incorporated into the main chains, and the copolymers were crosslinked. At the same time, the selectivity for C₄H₁₀/CH₄ pair was increased. The suggested approach has allowed obtaining crosslinked polymers from Si‐containing monomers without a loss of the main membrane characteristics. POLYM. ENG. SCI., 59:2502–2507, 2019. © 2019 Society of Plastics Engineers     

Preparation of composites of liquid‐crystalline matrix of poly(p‐phenylene‐sulfoterephthalamide) and CaCO3 by In situ mineralization

Liquid‐crystalline (LC) hydrogels were obtained from an aqueous solution of poly(p‐phenylene‐sulfoterephthalamide) (PPST) by the addition of calcium ions (Ca²⁺). The critical hydrogel formation ratio of Ca²⁺ to the sulfonic acid group in PPST (^crtR_Ca = [Ca²⁺]/[ ]) depended on the concentration of PPST, and was independent of the molecular weight of PPST. When the LC hydrogel was prepared at a concentration of 0.5 wt % and ^crtR_Ca = 0.6, and was exposed to ammonium carbonate vapor for 96 h, all Ca²⁺ in the LC hydrogel were converted into calcite crystals. The alternate soaking process for the LC hydrogel induced the formation of two mesocrystal morphologies on and in the Ca²⁺ cross‐linked LC hydrogel. Plate‐like calcite mesocrystals grew at the hydrogel/solution interface and cubic mesocrystals were present in the inner space of the hydrogel, thus composites with some ordered structures of LC matrix and CaCO₃ have been prepared through in situ mineralization. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41455.     

Stability constants of amidoximated chitosan‐g‐poly(acrylonitrile) copolymer for heavy metal ions

Amidoximated chitosan‐g‐poly(acrylonitrile) (PAN) copolymer was prepared by a reaction between hydroxylamine and cyano group in chitosan‐g‐PAN copolymer prepared by grafting PAN onto crosslinked chitosan with epychlorohydrine. The adsorption and desorption capacities for heavy metal ions were measured under various conditions. The adsorption capacity of amidoximated chitosan‐g‐PAN copolymer increased with increasing pH values, and was increased for Cu²⁺ and Pb²⁺ but a little decreased for Zn²⁺ and Cd²⁺ with increasing PAN grafting percentage in amidoximated chitosan‐g‐PAN copolymer. In addition, desorption capacity for all metal ions was increased with increasing pH values in contrast to the adsorption results. Stability constants of amidoximated chitosan‐g‐PAN copolymer were higher for Cu²⁺ and Pb²⁺ but lower for Zn²⁺ and Cd²⁺ than those of crosslinked chitosan. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 469–476, 1999     

Synthesis of new ionic crosslinked polymer hydrogel combining polystyrene and poly(4‐vinyl pyridine) and its self‐healing through a reshuffling reaction of the trithiocarbonate moiety under irradiation of ultraviolet light

A new ionic crosslinked polymer hydrogel was achieved by the strategy of ionically crosslinking α,ω‐dibromide terminated polystyrene (Br‐PS‐Br) with poly(4‐vinyl pyridine) (P4VP) which was synthesized by reversible addition‐fragmentation chain transfer polymerization using a chain transfer agent containing a trithiocarbonate moiety. The moiety of trithiocarbonate was introduced into the crosslinked network to show the self‐healing characteristics. The chain structure and components of Br‐PS‐Br and P4VP were characterized through ¹H NMR, gel permeation chromatography, Fourier transform IR spectroscopy and elemental analysis. The P4VP (M_n = 25 300 g mol^?1) chains were crosslinked with Br‐PS‐Br (M_n = 2000 g mol^?1) through the quaternization reaction to form a polymer network which was further crosslinked in acetonitrile by irradiation of UV light to fabricate a hydrogel. Such a hydrogel of P4VP/Br‐PS‐Br cut by a razor blade can be rapidly (1 h) and repeatedly (three times) healed through a reshuffling reaction of the trithiocarbonate moiety under irradiation by UV light. © 2018 Society of Chemical Industry     

Radiation initiated synthesis of 2‐acrylamidoglycolic acid grafted carboxymethyl cellulose as pH‐sensitive hydrogel

This article exploits a new approach for synthesis of carboxymethyl cellulose/poly 2‐acrylamidoglycolic acid by graft and crosslinked copolymerization in aqueous solution by a simple one‐step using γ‐radiation. The reaction parameters affecting the equilibrium swelling, i.e., mass ratio of AG to CMC and irradiation dose were systematically optimized to achieve a superabsorbent hydrogel with a maximum swelling capacity. The structure, crystallinity, thermal stability, and surface morphology were characterized by Fourier transform infrared spectroscopy (FT‐IR) and elemental analysis, X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), respectively. FTIR proved that the grafting reaction occurred between the hydroxyl group of CMC and PAG chain. The thermal analysis data show that the prepared hydrogel is more thermally stable than pure CMC. The swelling behaviors in distilled water in various pH solutions, temperature and various ionic salt solutions (NaCl as monovalent, CaCl₂ as divalent and FeCl₃ as trivalent) were investigated in detail. The effect of cationic salt solutions on the swelling had the following order: Na⁺ > Ca²⁺ > Fe³⁺. In addition, the pH‐reversibility was preliminarily investigated with alternating pH between 12 and 2. The equilibrium swelling of CMC/PAG was achieved in 70 min. The hydrogel was responsive to the pH and salts; it also has reversible swelling and deswelling character. POLYM. ENG. SCI., 54:2753–2761, 2014. © 2013 Society of Plastics Engineers     

Synthesis,characterization, metal sorption,and biological activity of poly(N‐heterocylic acrylamide)

N‐heterocyclic acrylamide monomers were prepared and then transferred to the corresponding polymers to be used as an efficient chelating agent. Polymers reacted with metal nitrate salts (Cu²⁺, Pb²⁺_, Mg²⁺, Cd²⁺, Ni²⁺, Co²⁺_, Fe²⁺) at 150°C to give metal‐polymer complexes. The selectivity of the metal ions using prepared polymers from an aqueous mixture containing different metal ion sreflected that the polymer having thiazolyl moiety more selective than that containing imidazolyl or pyridinyl moieties. Ion selectivity of poly[N‐(benzo[d]thiazol‐2‐yl)acrylamide] showed higher selectivity to many ions e.g. Fe³⁺, Pb²⁺, Cd²⁺, Ni²⁺, and Cu²⁺. While, that of poly[N‐(pyridin‐4‐yl)acrylamide] is found to be high selective to Fe³⁺ and Cu²⁺ only. Energy dispersive spectroscopy measurements, morphology of the polymers and their metallopolymer complexes, thermal analysis and antimicrobial activity were studied. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42712.     

Removal of heavy metal ions from aqueous solutions by radiation‐induced chitosan/(acrylamidoglycolic acid‐co‐acrylic acid) magnetic nanopolymer

An effective method was developed to isolate toxic heavy metal ions from the aqueous solution by the magnetic nanopolymers. The magnetic sorbent was prepared with radiation‐induced crosslinking polymerization of chitosan (CS), 2‐acrylamido‐glycolic acid (AMGA), and acrylic acid (AAc), which stabilized by magnetite (Fe₃O₄) as nanoparticles. The formation of magnetic nanoparticles (MNPs) into the hydrogel networks was confirmed by Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, and Scanning electron microscopy, which revealed the formation of MNPs throughout the hydrogel networks. The swelling behavior of the hydrogels and magnetic ones was evaluated at different pH values. The adsorption activity for heavy metals such as Cu²⁺ and Co²⁺ by nonmagnetic and magnetic hydrogels, Fe₃O₄/CS/(AMGA‐co‐AAc), in terms of adsorption amount was studied. It was revealed that hydrogel networks with magnetic properties can effectively be used in the removal of heavy metal ions pollutants and provide advantageous over conventional ones. POLYM. ENG. SCI., 55:1441–1449, 2015. © 2015 Society of Plastics Engineers     

Characteristics of poly(AAc5‐co‐HPMA3‐cl‐EGDMA15) hydrogel‐immobilized lipase of Pseudomonas aeruginosa MTCC‐4713

Four series of noble networks were synthesized with acrylic acid (AAc) copolymerized with varying amount of 2‐hydroxy propyl methacrylate or dodecyl methacrylate (AAc/HPMA or AAc/DMA; 5:1 to 5:5, w/w) in the presence of ethylene glycol dimethacrylate (EGDMA; 1, 5, 10, 15, and 20%, w/w) as a crosslinker and ammonium per sulfate (APS) as an initiator. Each of the networks was used to immobilize a purified lipase from Pseudomonas aeruginosa MTCC‐4713. The lipase was purified by successive salting out with (NH₄)₂SO₄, dialysis, and DEAE anion exchange chromatography. Two of the matrices, E_15a, i.e. [poly (AAc₅‐co‐DMA₁‐cl‐EGDMA₁₅)] and I_15c, i.e. [poly (AAc₅‐co‐HPMA₃‐cl‐EGDMA₁₅)], that showed relatively higher binding efficiency for lipase were selected for further studies. I_15c‐hydrogel retained 58.3% of its initial activity after 10th cycle of repetitive hydrolysis of p‐NPP, and I_15c was thus catalytically more stable and efficient than the other matrix. The I_15c‐hydrogel‐immobilized enzyme showed maximum activity at 65°C and pH 9.5. The hydrolytic activity of free and I_15c‐hydrogel‐immobilized enzyme increased profoundly in the presence of 5 mM chloride salts of Hg²⁺, NH₄⁺, Al³⁺, K⁺, and Fe³⁺. The immobilized lipase was preferentially active on medium chain length p‐nitrophenyl acyl ester (C:8, p‐nitrophenyl caprylate). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4636–4644, 2006     

CO2‐facilitated transport through poly(N‐vinyl‐γ‐sodium aminobutyrate‐co‐sodium acrylate)/polysulfone composite membranes

Poly(N‐vinyl‐γ‐sodium aminobutyrate‐co‐sodium acrylate) (VSA–SA)/polysulfone (PS) composite membranes were prepared for the separation of CO₂. VSA–SA contained secondary amines and carboxylate ions that could act as carriers for CO₂. At 20°C and 1.06 atm of feed pressure, a VSA–SA/PS composite membrane displayed a pure CO₂ permeation rate of 6.12 × 10^?6 cm³(STP)/cm² s cmHg and a CO₂/CH₄ ideal selectivity of 524.5. In experiments with a mixed gas of 50 vol % CO₂ and 50 vol % CH₄, at 20°C and 1.04 atm of feed pressure, the CO₂ permeation rate was 9.2 × 10^?6 cm³ (STP)/cm² s cmHg, and the selectivity of CO₂/CH₄ was 46.8. Crosslinkages with metal ions were effective for increasing the selectivity. Both the selectivity of CO₂ over CH₄ and the CO₂ permeation rate had a maximum against the carrier concentration. The high CO₂ permeation rate originated from the facilitated transport mechanism, which was confirmed by Fourier transform infrared with attenuated total reflectance techniques. The performance of the membranes prepared in this work had good stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 275–282, 2006     

Synthesis of new crosslinked porous ammonium‐based poly(ionic liquid) and application in CO2 adsorption

A new poly(ionic liquid) of N,N‐methylenebisacrylamide (MBA)‐crosslinked‐poly(4‐vinylbenzyltriethylammonium hexafluorophosphate)(MBA‐crosslinked‐P[VBTEA][PF₆]) is prepared through the ion exchange of KPF₆ with the precursor of MBA‐crosslinked‐P[VBTEA][Cl]; the precursor is synthesized by 4‐vinylbenzyltriethylammonium chloride and MBA via inverse suspension polymerization. MBA‐crosslinked‐P[VBTEA][PF₆] is a thermally stable (decomposes at nearly 300°C) and porous (apparent porosity of 64.3% and specific surface of 39.12 m²/g) polymer particle with high purity, as indicated by Fourier transformed infrared, energy dispersive spectroscopy, thermogravimetric, scanning electron microscopy, and porous analyses. It is observed that MBA‐crosslinked‐P[VBTEA][PF₆] has good CO₂ adsorption capability of 14.04 mg/g at 0.2 MPa and 25°C, and can be recovered by desorption at vacuum and 80°C, and reused with 99% CO₂ adsorption after four cycles. POLYM. ENG. SCI., 54:59–63, 2014. © 2013 Society of Plastics Engineers     

Preparation and properties of a salt‐resistant superabsorbent polymer

Crosslinked sodium polyacrylate was prepared by solution polymerization with N,N‐methylene‐bisacrylamide (bisAM) as crosslinking agent; it was subsequently surface‐crosslinked by ethylene glycol diglycidyl ether (EGDE) and then was modified with inorganic salt to obtain a superabsorbent with water absorbency in 0.9 wt % NaCl aqueous solution at atmosphere and applied pressure (P ≈ 2 × 10³ Pa) of 55 and 20 g.g^?1, respectively. Moreover, it also had excellent hydrogel strength. The effects of reaction temperature, reaction time, neutralization degree (ND) of acrylic acid, amount of initiator, crosslinking agent, and surface‐crosslinking agent, mass ratio of inorganic salt to initial superabsorbent, molar ratio of sodium aluminate (NaAlO₂) to potassium dihydrogen hyphosphate (KH₂PO₄) on water absorbency (WA) in 0.9 wt % NaCl aqueous, and the hydrogel modulus were investigated and optimized. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2532–2541, 2004     

Linear low‐density polyethylene‐g‐poly(acrylic acid)/(organo‐montmorillonite) hydrogel composite as hydrogel electrolytes for zinc–carbon batteries

A hydrogel composite that has been prepared by using waste linear low‐density polyethylene, acrylic acid, and organo‐montmorillonite (LLDPE‐g‐PAA/OMMT) is used as a hydrogel electrolyte. An absorbency test was used to determine the percentage of ZnCl₂ solution absorbed by the hydrogel composite. The swelling behavior of the hydrogel composite in the ZnCl₂ solution was then studied. The highest absorbency was recorded when the concentration of ZnCl₂ solution was 3 M. The conductivity of ZnCl₂‐hydrogel composite electrolytes is dependent on the solution's concentration. A mixture of ZnCl₂ solution with hydrogel composite yields a good hydrogel composite electrolyte with a conductivity of 0.039 S cm^?1 at 3 M ZnCl₂. The hydrogel composite electrolyte was used to produce zinc‐carbon cells. The fabricated cell gives capacity of 7.8 mAh, has an internal resistance of 9.9 Ω, a maximum power density of 15.78 mWcm^?2, and a short‐circuit current density of 43.75 mAcm^?2 for ZnCl₂‐hydrogel composite electrolytes. J. VINYL ADDIT. TECHNOL., 22:279–284, 2016. © 2014 Society of Plastics Engineers     

Synthesis,Characterization, and swelling behaviors of acrylic acid/carboxymethyl cellulose superabsorbent hydrogel by glow‐discharge electrolysis plasma

This article exploits a new approach for synthesis of acrylic acid/carboxymethyl cellulose (AA/CMC) superabsorbent hydrogel in aqueous solution by a simple one‐step using glow‐discharge electrolysis plasma, in which N,N′‐methylenebisacrylamide (MBA) was used as a crosslinking agent. The reaction parameters affecting the equilibrium swelling, that is, discharge voltage, discharge time, mass ratio of AA to CMC, content of crosslinker, and degree of neutralization, were systematically optimized to achieve a superabsorbent hydrogel with a maximum equilibrium swelling. The structure, thermal stability, and morphology of AA/CMC superabsorbent hydrogel were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction analysis, thermogravimetric analysis, and scanning electron microscopy. The swelling kinetics in distilled water and swelling behaviors in various pH solutions and salts solutions (NaCl, KCl, MgCl₂, CaCl₂, AlCl₃, and FeCl₃) were investigated in detail. The effect of six cationic salt solutions on the equilibrium swelling had the following order K⁺ > Na⁺ > Mg²⁺ > Ca²⁺ > Al³⁺ > Fe³⁺. In addition, the pH‐reversibility was preliminarily investigated with alternating pH between 6.5 and 2.0. The results showed that the equilibrium swelling of AA/CMC was achieved in 90 min. The hydrogel was responsive to the pH and salts, and was reversible swelling and deswelling behavior. POLYM. ENG. SCI., 54:2310–2320, 2014. © 2013 Society of Plastics Engineers     

Preparation and characterization of poly(N‐tert‐butylacrylamide‐co‐acrylamide) ferrogel

Magnetic‐field‐sensitive gel, called ferrogel, was prepared by a two‐step procedure in which first step requires synthesis of the poly(N‐tert‐butylacrylamide‐co‐acrylamide) [P(NTBA‐co‐AAm)] hydrogel and during second step magnetite (Fe₃O₄) particles were formed in the hydrogel via coprecipitation of Fe(II) and Fe(III) ions in alkaline medium at 70°C. The obtained ferrogel was characterized by attenuated total reflectance Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy combined with energy dispersive spectroscopy, and electron spin resonance measurements. The magnetic responsive of the ferrogel was also investigated by applying magnetic field to the ferrogel. The extent of a bending degree of the ferrogel depends on the applied magnetic field strength. In addition, the magnetic responsive studies also indicated that formed magnetite content in the hydrogel is high enough to achieve considerable magnetic response to external magnetic field. As a result, the P(NTBA‐co‐AAm) ferrogel may be useful for potential applications in magnetically controlled drug release systems, magnetic‐sensitive sensors, and pseudomuscular actuators. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009