Presence Of Methylenebisacrylamide Research Articles

On the dual crosslinking for functionality enhancement of poly (acrylamide-co-acrylic acid)/chitosan-aluminum (III) ions and its characterization and sensory hydrogel fibers

In this report, we present a dual crosslinking hydrogel fiber made from polyamine saccharides chitosan (CS), synthesized through UV polymerization. This process utilizes Irgacure 2959 and N,N′-Methylenebisacrylamide (MBAA) as initiators, followed by immersion in an aluminum chloride (AlCl3) solution. The resulting hydrogel incorporates a dual crosslinking mechanism, quantitatively studied via Nuclear Magnetic Resonance (NMR) spectroscopy. This mechanism involves chemical crosslinking through radical graft polymerization of acrylamide and acrylic acid onto CS in the presence of MBAA, and physical crosslinking through hydrogen bonding interactions between P(AAm-co-AA) and a metal coordination bond. The mechanical properties of the hydrogel fiber enable it to withstand stresses up to 656 kPa and strains exceeding 300 %. Additionally, the hydrogel fiber exhibits conductivity at 1.96 Scm−1. Serving as a multifunctional material, it acts as a strain sensor and finds utility in optics. Remarkably, it demonstrates the capability to detect human motions such as finger bending and minor deformations like vibrations of the vocal cords. Furthermore, its ability to guide dynamic light makes it promising for optical applications. Consequently, this multifunctional hydrogel fiber emerges as a highly promising candidate for diverse applications in fields such as bioengineering and electronics.

Synthesis of Hydrogel Based on Poly (Acrylic Acid–Co‐Vinyl Acetate) Grafted on Modified Recycled Cellulose for Use in Fertilizer Slow‐Release System

The aim of this work is a synthesis of suitable hydrogel to produce slow‐release fertilizer using recycled cellulose which is obtained from waste paper. For this purpose, initially, we extracted alpha cellulose from waste paper and modified it to obtain carboxymethyl cellulose (CMC). Then, the CMC was converted to a suitable hydrogel through in situ graft copolymerization of acrylic acid and vinyl acetate in the presence of methylene bisacrylamide as a crosslinker. The various factors that affect hydrogel synthesis, such as the amounts of CMC, monomers, initiator, and crosslinker, were evaluated. In the optimized formulation, the weight ratio of monomers to CMC is 7, the molar ratio of monomers to each other is 1, and the crosslinker is used as 3 molar percent of monomers. The products were characterized using Fourier transform infrared, thermal gravimetric analysis, and scanning electron microscope analyses. The swelling behavior of the synthesized hydrogels was evaluated in different environments, such as distilled water, tap water, salt water, and different pH levels. The swelling ratio increases with an increase in pH level. Between the synthesized hydrogels, the best one was selected for slow‐release fertilizer production and loaded with 20‐20‐20 fertilizer (NPK), and the release behavior was evaluated. In an alkaline pH, there was a long time for NPK release within a slow‐release medium and even after 361 h, the release process was continued. Also, the performance of the fertilizer‐loaded hydrogel in soil using water holding capacity and water retention ratio tests were evaluated.

In situ preparation of MOF-199 into the carrageenan-grafted-polyacrylamide@Fe3O4 matrix for enhanced adsorption of levofloxacin and cefixime antibiotics from water

In this research study, a novel method, an in-situ growth approach, to incorporate metal-organic framework (MOF) into carrageenan-grafted- polyacrylamide-Fe3O4 substrate was introduced. Carrageenan-grafted-polyacrylamide-Fe3O4/MOF nanocomposite (kC-g-PAAm@Fe3O4-MOF-199) was fabricated utilizing three stages. In this way, the polyacrylamide (PAAm) was grafted onto the carrageenan (kC) backbone via free radical polymerization in the presence of methylene bisacrylamide (MBA) as cross-linker and Fe3O4 magnetic nanoparticles. Next, the kC-g-PAAm@Fe3O4 was modified by MOF-199 via an in-situ solvothermal approach. Several analyses such as Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-Dispersive X-ray Spectroscopy (EDX), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), Brunauer-Emmett-Teller (BET) demonstrated the successful synthesis of kC-g-PAAm@Fe3O4-MOF-199 magnetic hydrogel nanocomposite. The XRD pattern of magnetic hydrogel nanocomposite illustrated characteristic peaks of Fe3O4, neat kC, and MOF-199 with enhanced crystallinity in comparison with kC-g-PAAm@Fe3O4. TGA showed it has a char yield of 24 wt% at 800 °C. VSM confirmed its superparamagnetic behavior (with Ms of 8.04 emu g−1), and the BET surface area of kC-g-PAAm@Fe3O4-MOF-199 was measured at 64.864 m2 g−1, which was higher than that of kC-g-PAAm@Fe3O4 due to the highly porous MOF-199 incorporation with a BET surface area of 905.12 m2 g−1). The adsorption effectiveness of kC-g-PAAm@Fe3O4-MOF-199 for eliminating cephalosporin and quinolones antibiotics, i.e., Cefixime (CFX) and Levofloxacin (LEV) from the aquatic area was considered. Several experimental setups were used to evaluate the efficacy of adsorption, such as solution pH, amount of adsorbent, contact duration, and initial concentration. The maximum adsorption capacity (Qmax) of the prepared magnetic hydrogel nanocomposite was found to be 2000 and 1666.667 mg−1 for LEV and CFX using employing 0.0025 g of adsorbent. The Freundlich isotherm model well described the experimental adsorption data with R2CFX = 0.9986, and R2LEV = 0.9939. And the adsorption kinetic data were successfully represented by the pseudo-second-order model with R2LEV = 0.9949 and R2CFX = 0.9906. Hydrogen bonding, π-π interaction, diffusion, and entrapment in the hydrogel network all contributed to the successful adsorption of both antibiotics onto the kC-g-PAAm@Fe3O4-MOF-199 adsorbent. Other notable physicochemical properties include the three-dimensional structure and availability of the reactive adsorption sites. Moreover, the adsorption/desorption efficacy of magnetic hydrogel nanocomposites was not significantly diminished after four cycles of recovery.

Gamma‐Irradiation‐Assisted Synthesis and Characterization of Xanthan Gum/Agar/Gelatin/ZnO Nanocomposite Hydrogels and their Antimicrobial Activity

AbstractNanocomposite biohydrogels comprised of Xanthan gum, Agar, and Gelatin including different weight ratios of Zinc oxide nanoparticles (ZnO−NPs) have been prepared via gamma irradiation technique in presence of methylene bis acrylamide (MBAm) as a crosslinking agent to be employed as antibacterial environmentally benign formulations. The prepared hydrogels were characterized by several techniques: Fourier‐transform infrared spectroscopy for confirming the chemical structure, X‐ray diffraction for crystallographic features and thermal gravimetric analysis for thermal properties. The AFM and SEM were used for investigating the surface features and morphology of the biohydrogels. The results showed that both Gamma irradiation and incorporation of ZnO−NPs improve the gel (wt %) of the prepared biohydrogel nanocomposite from 42.8±1.5 wt% for the unirradiated composite to 81.2±0.9 wt% after exposed to 20 kGy and reaches to 92±0.68 wt% in addition of 0.5×10−2 g of ZnO−NPs. Also, the effect of ZnO−NPs on the antimicrobial activity of the biohydrogel was verified. It was found that the prepared nanocomposite biohydrogels possess good thermal stability and remarkable antimicrobial activity towards different pathogens, thus they can be used in possible biological applications.

Development and evaluation of chitosan-g-poly(acrylic acid-co-acrylamide) hydrogel composite containing gabapentin for in vitro controlled release

In this study, a biocompatible and biodegradable hydrogel nanocomposite was synthesized through copolymerization of acrylic acid and acrylamide monomers onto chitosan in the presence of methylene bisacrylamide as a crosslinking agent and ammonium persulfate as a thermal initiator. The hydrogel was fully characterized by FTIR, SEM, DSC, and TGA techniques. The drug delivery and controlled release of gabapentin (GAB) at different pH, temperature, and time intervals were studied using the synthesized hydrogel nanocomposite. Based on the results, the maximum encapsulation and the drug loading efficiency of hydrogel composite was 64% and 71%, respectively, in which the drug was released in a sustained-release manner from the hydrogel. The release study of dual temperature and pH-responsive hydrogel composite indicated that 90% of total GAB was released from the hydrogel within the first two hours. The drug release was governed by the Higuchi kinetics model with R2= 0.9939 and followed the Fickian diffusion mechanism. The cytotoxicity of the blank hydrogel composite was evaluated on the NIH/3T3 cell line. The findings revealed that hydrogel did not affect the cells’ survival. The unique biocompatibility and thermosensitive properties of the present chitosan-based hydrogel could be a reason to use it as a promising drug carrier for the controlled and sustained release of GAB.

Performance improvement of poly(acrylic acid) binder-based silicon/graphite composite anodes by room temperature electron beam irradiation-induced crosslinking

In this study, we demonstrated that the enhanced performance of poly(acrylic acid) binder-based silicon/graphite composite anode (c-PAA-Si/C) can be achieved by a quick, scalable, and solid-state electron beam irradiation-induced crosslinking in the presence of methylenebisacrylamide (MBA) as a water-soluble crosslinker. The result from analysis of an irradiated PAA binder film revealed that the PAA was completely crosslinked by the electron beam irradiation at the absorbed dose of 30 kGy in the presence of 10 wt% MBA, thereby leading to the much reduced swelling degree and improved tensile strength. Likewise, the c-PAA-Si/C-30 anode (irradiated at absorbed dose of 30 kGy) possessed higher hardness than the non-irradiated PAA-Si/C-0 probably due to the effective formation of the crosslinked structure. Moreover, based on the coin-type half cell performance and cycle stability test, the c-PAA-Si/C-30 anode-based cell exhibited the better retention capacity at 100 cycles than that of the PAA-Si/C-0-based one. The EIS and FE-SEM results showed that this better cycling performance could be ascribed to the crosslinked structure-induced structural stability.

Synthesis of chitosan-grafted poly-acrylic acid (CTS-g-PAA) hydrogel and its potential application in biosensors for signal enhancing and bioanalysis.

Nowadays, hydrogels have been attracted a lot of interest due to their immense potential in different fields such as biomedicine and biotechnology. Biodegradable and biocompatible pH-sensitive chitosan-grafted polyacrylic acid (CTS-g-PAA) hydrogel was synthesized by grafting an acrylic acid monomer onto chitosan at the presence of methylene bisacrylamide as a cross-linking agent and ammonium persulphate as an initiator. FT-IR spectroscopy and scanning electron microscopy (SEM) were used to analyze the properties of the obtained hydrogel. The synthesized hydrogel is suitable for the delivery of many hydrophilic drugs or species. Using a multi-walled carbon nanotube modified-glassy carbon electrode (CNT-GCE), the loading and release conditions of Nile Blue (NB) as an electroactive compound were evaluated utilizing the differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The effect of various parameters on the electrochemical signal of NB was investigated, and the optimal conditions for the efficient performance of hydrogel to delivery of NB were obtained. The electrocatalytic current values show linear dependence to NB concentration in the range of 0.098 – 0.971 μM while the detection limit of this electrochemical platform was 12.3 nM. The unique proposed hydrogel with the electroactive NB has a broad range of possible applications in biosensors for signal enhancement and bioanalysis.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10854-021-06939-7.

Synthesis of Poly(Acrylamide-Graft-Chitosan) Hydrogel: Optimization of The Grafting Parameters and Swelling Studies

Hydrogel polymers were prepared via graft polymerization of acrylamide (AAm) onto chitosan (CTS) backbone in the presence of methylene bisacrylamide (MBA) as cross-linker and ammonium persulfate (APS) as an initiator. Optimizing the crosslinking graft reaction of AAm onto CTS was studied by varying the concentration of CTS and MBA cross-linker and discussing the effect of these conditions on the gel fraction and the grafting parameters. The grafting parameters; grafting percentage (%GP), grafting efficiency (%GE), Add-on (%A) and homopolymer (%H) were studied as a function of the chitosan and the cross-linker concentrations. Also the swelling properties of the prepared hydrogel were examined. In this research, the simple second order kinetic model proposed by Schott has been carried out to describe the swelling mechanism. The effect of the grafting reaction on the thermal properties of the chitosan was also investigated by the thermal gravimetric analysis (TGA). The structure of the prepared hydrogel polymer was confirmed by FT-IR spectra. The porous structure of the hydrogel was observed by the Scanning Electron Microscope (SEM) and also the elemental composition of the prepared hydrogel was identified by using the energy dispersive X-ray (EDX).

Studies on the photoelectric properties of crosslinked-poly(acrylamide co-acrylic acid) for photo detector applications

Abstract The co-polymer, polyacrylamide co-acrylic acid-P(AM-AA) was prepared by chemical polymerization of acrylamide with acrylic acid in presence of methylene bisacrylamide as a crosslinker. The copolymer was analyzed using FTIR, XRD and DTA. The I-V characteristics of the copolymer were studied and proved that the recombination process is dependent on the presence of traps distributed in the energy gap. The results showed that the traps contribute significantly in the increased photosensitivity of the co-polymer. The behaviors of both dark and photoconductivity with temperature showed linear relations at different light intensities and proved an activated conduction with single activation energy. The activation energy (Ea) at different light intensity was found to follow Meyer Neldel rule (MN rule) and the intercept σo (pre factor) as well. The characteristic energy of exponential traps was found to be within 0.0134–0.009 eV, at different light intensities. The transient photoconductivity studies on the co-polymer confirmed the presence of traps. Where, the high photosensitivity and the presence of traps may contribute to the development of the improved performance of photo detectors.

Controlled release of phosphorous fertilizer bound to carboxymethyl starch-g-polyacrylamide and maintaining a hydration level for the plant

A controlled release fertilizer system based on phosphate bound-carboxymethyl starch-graft-polyacrylamide (P-CMS-g-PAM) has been prepared in order to deliver the phosphate fertilizer to the plant at a constant rate thereby. This system aims to increase fertilizer phosphorus use efficiency (FPUE) and maintain a hydration level for the plant at the same time. Two types of starch phosphate monoesters were prepared using mono-ammonium (MAP) and di-ammonium phosphate (DAP). First, starch was converted to carboxymethyl starch and then was phosphorylated with mono-ammonium dihydrogen phosphate and di-ammonium dihydrogen phosphate. After phosphorylation, the samples were grafted with acrylamide in the presence of methylene bisacrylamide as a crosslinking agent. The prepared systems of P-CMS-g-PAM were differently characterized by Fourier transformer infrared (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and phosphorous analysis. The swelling behavior was investigated. The kinetics of grafting reaction were also studied. The release behavior of phosphate bound was studied at pH 7 and 25 °C. The mechanism of the phosphate release from P-CMS-g-PAM was examined using the Korsmeyer-Peppas model.

Synthesis, characterization and adsorption properties of microcrystalline cellulose based nanogel for dyes and heavy metals removal

Recently, naturally occurring biopolymers have attracted the attention as potential adsorbents for the removal of water contaminants. In this work, we present the development of microcrystalline cellulose (MCC)-based nanogel grafted with acrylamide and acrylic acid in the presence of methylene bisacrylamide and potassium persulphate as a crosslinking agent and initiator, respectively. World-class facilities such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), surface analysis, field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and zeta sizer were used to characterize the synthesized MCC based nanogel. The prepared nanogel was applied to remove reactive red 195 (RR195) dye and Cd (II) from aqueous medium at different operational conditions. The adsorption experiments showed that the feed concentration of monomers has a significant effect on the removal of RR195 which peaked (93% removal) after 10min of contact time at pH2 and a dose of 1.5g/L. On contrary, the feed concentration has insignificant effect on the removal of Cd (II) which peaked (97% removal) after 30min of contact time at pH6 and a dose of 0.5g/L. The adsorption equilibrium data of RR195 and Cd (II) was best described by Freundlich and Langmuir, respectively. Conclusively, the prepared MCC based nanogels were proved as promising adsorbents for the removal of organic pollutants as well as heavy metals.

Synthesis of poly(ethylene glycol) di-itaconate and investigation of its influence on acrylamide based hydrogels meant for water treatment

Poly(ethylene glycol) (PEG 1500) is functionalized using itaconic acid by melt esterification reaction to obtain a bi-functional co-monomer crosslinker, Poly(ethylene glycol) di-itaconate. The resulting product has been copolymerized with acrylamide in presence of methylene bis-acrylamide as crosslinker (in varying proportions) so as to prepare hydrogel which is mostly recommended for dye removal from textile effluents. FTIR-ATR, Solid state 13-C NMR and WAXS techniques are used to ensure grafting of the PEG diitaconate on the polyacrylamide backbone. The intermediate products are also characterized using FTIR and 1H NMR spectroscopy. This study reveals that a significant improvement in gel characteristics particularly in respect of swelling properties may be achieved with the hydrogel having only ester type crosslinks. However this is attained at the cost of yield stress. The ester based gel shows better storage modulus, dye sorption ability and the anti-fungal properties in relation to semi-IPN type gels.

Synthesis of cellulose-based superabsorbent hydrogels by high-energy irradiation in the presence of crosslinking agent

Superabsorbent hydrogels were prepared from aqueous solutions of four cellulose derivatives (carboxymethylcellulose Na-salt – CMC, methylcellulose – MC, hydroxyethylcellulose – HEC and hydroxypropylcellulose – HPC) by gamma irradiation initiated crosslinking. CMC was used for the majority of the measurements. N,N’-methylene-bis-acrylamide (MBA) crosslinking agent was used to modify the gel properties. The crosslink density increased with the MBA concentration, leading to an improved gel fraction and lower water uptake. The crosslinking efficiency was the highest up to 1 w/wpolymer% MBA concentration. Very high MBA content (10 w/wpolymer%) led to a heterogeneous gel structure. Gelation also occurred under milder conditions in the presence of MBA: good gel properties were achieved at significantly lower doses and solute concentrations as compared to crosslinker-free solutions. The time required to reach maximum water uptake increased with the degree of swelling in equilibrium. Swelling properties of CMC gels with lower water uptake showed lower sensitivity to the ionic strength of the solvent.

Effect of Electron Beam Irradiation Crosslinking on PVA Films

Electron beam irradiation cross-linking of polyvinyl alcohol (PVA) films with the presence of N, N'- methylene bisacrylamide (MBA) were studied, improving the thermal stability. The films unirradiated and irradiated were characterized by ATR-FTIR spectroscopy, X-ray diffraction, differential scanning calorimetry and thermo gravimetric analysis. The PVA films with the presence of MBA would crosslink after irradiation. The crystallinity increased firstly and then decreased as a function of irradiation dose, while the melting temperature decreased with increasing the dose. Beside, the T30%, T50%, T90% and Tmax temperature of degradation increased as the irradiation dose increased.

Synthesis of a Novel Pectin-Based Superabsorbent Hydrogel with Salt and pH-Responsiveness Properties

A novel smart superabsorbent hydrogel with salt- and pH-responsiveness properties was obtained by grafting of mixtures of acrylic acid (AA) and acryl amide (AM) monomers onto pectin, using ammonium persulfate (APS) as a free radical initiator in the presence of methylene bisacrylamide (MBA) as a crosslinker. The graft copolymerization conditions were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. Infrared spectroscopy was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM) and thermogravimetric analysis TGA. Results from SEM observation also showed a porous structure with smooth surface morphology of the hydrogel. The swelling variations of hydrogels were explained according to swelling theory based on the hydrogel chemical structure. The hydrogels exhibited salt-sensitivity and cation exchange properties. The pH-reversibility property of the hydrogels makes the intelligent polymers as good candidates for considering as potential carriers for bioactive agents, e.g. drugs.

Crosslinked Graft Copolymer of Methacrylic Acid and Gelatin as a Novel Hydrogel with pH-Responsiveness Properties.

In this paper, a novel gelatin-based hydrogel was synthesized through crosslinking graft copolymerization of methacrylic acid (MAA) onto gelatin, using ammonium persulfate (APS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. A proposed mechanism for hydrogel formation was suggested and the structure of the product was established using FTIR spectroscopy and gravimetric analysis of the products. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA/DTG). The effect of reaction variables such as concentration of APS and MBA were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The gelatin-g-PMAA hydrogel exhibited a pH-responsiveness character so that a swelling-deswelling pulsatile behavior was recorded at pHs 2 and 8. This on-off switching behavior makes the hydrogel as a good candidate for controlled delivery of bioactive agents.

Poly(ethylene glycol)–carboxymethyl chitosan-based pH-responsive hydrogels: photo-induced synthesis, characterization, swelling, and in vitro evaluation as potential drug carriers

In this study, carboxymethyl chitosan was prepared, characterized, and then photo-induced graft copolymerized with poly(ethylene glycol) under a nitrogen atmosphere in aqueous solution using 2,2-dimethoxy-2-phenyl acetophenone (DMPA) as the photo-initiator. The grafting copolymerization process was confirmed and the resulting copolymers were characterized using differential scanning calorimetry (DSC), FTIR spectroscopy, 2D-X ray diffraction, and elemental analysis. The kinetics of the grafting reactions was also studied. Under the applied experimental conditions, the optimum grafting values were obtained at: CMCs = 0.2 g, PEGA = 249 mM, DMPA = 10.4 mM at a 2 h reaction time. Some of the resulting copolymers were selected and used in the presence of methylene bisacrylamide (MBA) as a crosslinking agent to develop pH-responsive hydrogel matrices. The swelling characteristics and the in vitro release profiles of 5-fluorouracil (5-FU), as a model drug, from the hydrogels were investigated. The results revealed that the hydrogel matrices developed in this study can be customized to act as good candidates in drug delivery systems.

Controlled release of diclofenac sodium from pH-responsive carrageenan-g-poly(acrylic acid) superabsorbent hydrogel

In this paper, controlled release of diclofenac sodium (DS) from pH-sensitive carrageenan-g-poly( acrylic acid) superabsorbent hydrogels was investigated. The hydrogels were prepared by graft copolymerization of acrylic acid (AA) onto kappa-carrageenan, using ammonium persulfate (APS) as a free radical initiator in the presence of methylene bisacrylamide (MBA) as a crosslinker. Infrared spectroscopy was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM). The synthesized hydrogels were subjected to equilibrium swelling studies in simulated gastric and intestinal fluids (SGF and SIF). Hydrogels containing drug DS, at different drug-to-polymer ratios, were prepared by direct adsorption method. The loading yield was found to depend on both the impregnation time and the amount of encapsulated drug. In vitro drug-release studies in different buffer solutions showed that the most important parameter affecting the drug-release behaviour of hydrogels is the pH of the solution. The mechanism involved in release was Fickian (n ⩽ 0·43, n = 0·348) and Super Case II kinetics (n > 1, n = 1·231) at pH 1·2 and 7·4, respectively.

Synthesis and super-swelling behavior of a novel low salt-sensitive protein-based superabsorbent hydrogel: collagen-g-poly(AMPS)

Superabsorbent polymers are obtained by the graft copolymerization of 2-acrylamido-2-methylpropanesul- fonic acid (AMPS) monomer onto collagen, using ammonium persulfate as a free radical initiator in the presence of methylene bisacrylamide as a crosslinker. Infrared spectroscopy and TGA thermal analysis were carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was examined by scanning electron microscopy (SEM). The effect of reaction variables on swelling capacity was investigated to achieve a hydrogel with improved water absorbency. Under the optimized conditions concluded, maximum capacity of swelling in distilled water was found to be 268 g/g. The swelling ratio in various salt solutions was investigated in detail. Since this hydrogel exhibited a very high absorptivity in saline, it may be referred to as a low salt-sensitive superabsorbent. The collagen-g-AMPS hydrogel also showed cation exchange properties. The swelling kinetics of the synthesized hydrogels with various particle sizes was also preliminarily investigated.

A new salt-resistant superabsorbent hydrogel based on kappa-carrageenan

AbstractIn this work, a novel biopolymer-based superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of 2-hydroxyethyl acrylate (HEA) onto kappa-carrageenan, using potassium persulfate (KPS) as a free radical initiator in the presence of methylene bisacrylamide (MBA) as a crosslinker. The chemical structure of the hydrogels was confirmed by FTIR spectroscopy. The morphology of the samples was examined by scanning electron microscopy (SEM). The certain variables of the graft copolymerization (i.e. the monomer, the initiator, the polysaccharide, and the crosslinker concentration) were systematically optimized to achieve a hydrogel with maximum swelling capacity. The swelling ratio in various salt solutions was also investigated in detail. Since this hydrogel exhibited a very high absorptivity in saline, it may be referred to as low salt sensitive superabsorbent. The swelling of superabsorbing hydrogels was also measured in solutions with pH ranging from 1 to 13.