Synthesis and characterization of super‐absorbent hydrogels based on hemicellulose

A kind of novel hemicellulose‐based hydrogel with excellent water absorbency was synthesized by the graft copolymerization of acrylic acid (AA), acrylic amide (AM) with hemicellulose. The various factors that influenced the water absorbency of the modified hemicellulose were studied, including AA content, hemicellulose content, neutralization degree of AA, and weight ratio (to monomer) of cross‐linker and initiator. The optimal conditions were found as follows: m(AA) : m(AM) : m(hemicellulose) = 15 : 3.5 : 1, the neutralization degree of AA was 75%, and weight ratio (to monomers) of the cross‐linker and the initiator was 0.03% and 1.0%, respectively. The maximum absorbencies toward distilled water and 0.9 wt % NaCl solution were 1128 g/g and 132 g/g, respectively. The characteristics of the hydrogels were also investigated by Fourier Transform InfraRed (FT‐IR), scanning electron microscope (SEM), and atomic force microscope (AFM). The results indicated that the undulant surface and broad network structure offer the hydrogels excellent water absorbency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42441.     

Utilization of starch and montmorrilonite for the preparation of superabsorbent nanocomposite

Starch and montmorrilonite (MMT) were used as raw materials for synthesizing starch‐graft‐poly[acrylamide (AM)–acrylic acid (AA)]/MMT superabsorbent nanocomposite by graft and intercalation copolymerization reaction of starch, AM, and AA in the presence of organic MMT micropowder in aqueous solution. Major factors affecting water absorbency such as weight ratio of monomers to starch, weight ratio of AM to AA, neutralization degree of AA, amount of crosslinker, initiator, and MMT were investigated. The superabsorbent nanocomposite synthesized under optimal synthesis conditions exhibits absorption of 1120 g H₂O/g sample and 128 g H₂O/g sample in deionized water and in 0.9 wt % NaCl solution, respectively. IR spectra showed that the graft copolymerization between  OH groups on MMT and monomers took place during the reaction, and that crystal interlayer was pulled open in the superabsorbent nanocomposite. X‐ray diffraction analysis showed that the crystal interlayer of MMT was pulled open to 2.73 nm, and thus formed nanometer exfoliation composite material. Thermogravimetric analysis showed that starch‐graft‐poly (AM–AA) superabsorbent nanocomposite (8 wt % MMT) has good thermal stability. This superabsorbent nanocomposite with excellent water absorbency and water retention, being biodegradable in nature, economical and environment friendly, could be especially useful in industry, agricultural, and horticultural applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of superabsorbent based on the graft copolymerization of acrylic acid and acrylamide onto konjac glucomannan and its application in the water retention in soils

A new konjac glucomannan (KGM)-based superabsorbent polymer, KGM-g-poly(acrylic acid-co-acrylamide), was prepared by the free radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto KGM in the presence of N,N′-methylenebisacrylamide as a crosslinker with potassium persulfate as an initiator. The effects of reaction parameters, including the amount of crosslinking agent and initiator, the weight ratio of both (AA + AM) to KGM and AM to (AA + AM), neutralization degree of AA, bath temperature, and reaction time, on the water absorbency of the superabsorbent were investigated. The Fourier transform infrared spectroscopy was used to characterize the structures of the copolymer. The maximum water absorbency of the optimized product was 650 g/g for distilled water and 70 g/g for a 0.9 wt % aqueous NaCl solution. Furthermore, the water retention of the copolymer in soils was studied. The effect of the copolymers on the aggregate distribution of soils was also evaluated. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Multilayer‐coated NPK compound fertilizer hydrogel with controlled nutrient release and water absorbency

A novel trilayered controlled‐release nitrogen, phosphorous, and potassium (NPK) fertilizer hydrogel was prepared by dipping the NPK fertilizer granules sequentially in 7% w v^?1 poly(vinyl alcohol) (PVA) and 2% w v^?1 chitosan (CS) solutions and then cross‐linking the CS layer (cross‐CS) via glutaraldehyde vapor deposition. Different NPK fertilizer hydrogels were then synthesized by inverse suspension polymerization of the dried PVA/cross‐CS bilayer‐coated fertilizer granules in various molar ratios of acrylamide (AM) and acrylic acid (AA) monomers, and polymerization with varying molar ratios of ammonium persulfate, N,N,N′,N′‐tetramethylethylenediamine and N,N′‐methylenebisacrylamide (N‐MBA). The water dissolution time of the obtained PVA/cross‐CS/poly (AA‐co‐AM) trilayer‐coated NPK fertilizer hydrogel granules was prolonged, while the water absorbency increased with increasing AA contents, and decreased with increasing N‐MBA contents in the outer poly(AA‐co‐AM) coating. The optimal trilayer‐coated NPK fertilizer hydrogel obtained released 84 ± 18, 63 ± 12, and 36 ± 15% of the N, P, and K nutrients, respectively, after a 30‐day immersion in water. The release phenomena of the N, P, and K nutrients of the fertilizer hydrogel obeyed both the Korsmeyer‐Peppas and Ritger‐Peppas models with a pseudo‐Fickian diffusion mechanism. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41249.     

Superabsorbent polymeric materials X: Effect of degree of neutralization on swelling behavior of crosslinked poly(sodium acrylate) in aqueous salt solutions

A series of xerogels based on different degrees of neutralizations (DN) of acrylic acid (AA) and N,N-methylene-bis-acrylamide (NMBA) were prepared by inverse suspension polymerization. The influence of the DN values of AA on water absorbency and swelling behavior for these highly absorbent polymers in deionized water and various saline solutions were investigated. Results indicate that the equilibrium-water absorbency (Q_eq) increases with an increase in the DN of AA until the DN value reaches 95% and then decreases at 100% of the DN value. However, the initial absorption rate for these gels decreases with an increase in the DN value of AA in both deionized water and 0.9 wt% NaCl solution. The adsorption of copper ions by these gels was also investigated.     

Superabsorbent hydrogel of acrylic acid/potassium acrylate copolymers by ultraviolet photopolymerization: Synthesis and properties

Synthesis of superabsorbent hydrogel (SAHG) of acrylic acid‐potassium acrylate copolymer by direct Ultraviolet (UV) photopolymerization is a new method. The effects of degree of neutralization of acrylic acid (AA), photoinitiators, crosslinking agents, and exposure time of UV light on water absorbent properties were investigated. The results showed that the water absorbency (Q) and the salt solution (NaCl, 0.9%) absorbency (Qs) of SAHG, based on Irgacure 651, are high, reaching about 1400 and 130 mL/g, respectively. UV absorption spectrum proved that peak of UV absorption of Irgacure 651 matched the UV light source we used. Among the crosslinking agents, N,N′‐methylene bisacrylamide is more efficient than others, because of its very small content and high Q. ¹³C NMR spectrometry was used to identify the mechanism of crosslinking reaction through esterification of hydroxyethyl acrylate (HEA) and 2‐hydroxypropyl acrylate (HPA) with carboxylic acid group in acrylic acid‐ammonium acrylate copolymerization, but efficiency of crosslinking reaction by esterification was lower than that of copolymerization of vinyl group in crosslinking agent. The Q of acrylic acid‐potassium acrylate copolymer of SAHG reaches 1592 mL/g under the following conditions: degree of neutralization of acrylic acid is 80%, content of Irgacure 651 is 0.25 wt %, content of HEA is 0.2 wt %, and exposure time is 10 min. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1181–1187, 2006     

Characterization of stabilized porous magnetite core–shell nanogel composites based on crosslinked acrylamide/sodium acrylate copolymers

Stabilized and dispersed superparamagnetic porous nanogels based on sodium acrylate (AA‐Na) and acrylamide (AM) in a surfactant‐free aqueous system were synthesized via solution polymerization at room temperature. The formation of magnetite nanoparticles was confirmed and their properties characterized using Fourier transform infrared spectroscopy. Extensive characterization of the magnetic polymer particles using transmission electron microscopy (TEM), dynamic light scattering and zeta potential measurements revealed that Fe₃O₄ nanoparticles were incorporated into the shells of poly(AM/AA‐Na). The average particle size was 5–8 nm as determined from TEM. AM/AA‐Na nanoparticles with a diameter of about 11 nm were effectively assembled onto the negatively charged surface of the as‐synthesized Fe₃O₄ nanoparticles via electrostatic interaction. Crosslinked magnetite nanocomposites were prepared by in situ development of surface‐modified magnetite nanoparticles in an AM/AA‐Na hydrogel. Scanning electron microscopy was used to study the surface morphology of the prepared composites. The morphology, phase composition and crystallinity of the prepared nanocomposites were characterized. Atomic force microscopy and argon adsorption–desorption measurements of Fe₃O₄.AM/AA indicated that the architecture of the polymer network can be a hollow porous sphere or a solid phase, depending on the AA‐Na content. © 2013 Society of Chemical Industry     

Synthesis and properties of carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide) as a novel cellulose‐based superabsorbent

A new cellulose‐based superabsorbent polymer, carboxymethyl cellulose‐graft‐poly(acrylic acid‐co‐acrylamide), was prepared by the free‐radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto carboxymethyl cellulose (CMC) in the presence of N,N′‐methylenebisacrylamide as a crosslinker with a redox couple of potassium persulfate and sodium metabisulfite as an initiator. The influences of reaction variables such as the initiator content, crosslinker content, bath temperature, molar ratio of AA to AM, and weight ratio of the monomers to CMC on the water absorbency of the carboxymethylcellulose‐graft‐poly(acrylic acid‐co‐acrylamide) copolymer were investigated. The copolymer's structures were characterized with Fourier transform infrared spectroscopy. The optimum reaction conditions were obtained as follows: the bath temperature was 50°C; the molar ratio of AA to AM was 3 : 1; the mass ratio of the monomers to CMC was 4 : 1; and the weight percentages of the crosslinker and initiator with respect to the monomers were 0.75 and 1%, respectively. The maximum water absorbency of the optimized product was 920 g/g for distilled water and 85 g/g for a 0.9 wt % aqueous NaCl solution. In addition, the superabsorbent possessed good water retention and salt resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1382–1388, 2007     

The release of cefazolin from chitosan/polyvinyl alcohol/sepiolite nanocomposite hydrogel films

Films of chitosan/polyvinyl alcohol (PVA)/sepiolite nanocomposite were prepared by a simple and “green” route through solution mixing; followed by freezing–thawing cycles. The structures of nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis, X-ray diffractometry, and Fourier transform infrared spectroscopy. The SEM and TEM micrographs confirmed a needle-type dispersion of sepiolite nanoclay in the hydrogel nanocomposites. The effects of sepiolite and chitosan/PVA weight ratio on the swelling of nanocomposites were investigated. The water absorbency of nanocomposites was decreased by introducing sepiolite nanoclay. The nanocomposites with high content of chitosan showed high swelling capacity. The nanocomposite films showed pH-dependent swelling behavior with a maximum water absorbency under acidic pH. The cefazolin with a broad-spectrum activity toward gram-positive and gram-negative bacteria was loaded in hydrogels. The release of cefazolin from nanocomposites was evaluated at pH 7.4. The content of released drug was affected by both sepiolite amount and chitosan/PVA weight ratio. The nanocomposites films released more cefazolin than the neat hydrogel film. Cefazolin-loaded nanocomposites showed the antibacterial activity with a large zone of inhibition against gram-positive Bacillus cereus bacterium.     

Swelling study of superabsorbent PAA‐co‐PAM/clay nanohydrogel

A series of superabsorbent composites were prepared from acrylic acid (AA), acrylamide (AM), and Cloisite® 30B by aqueous solution polymerization technique using ammonium peroxodisulfate (APS) as initiator. The interaction of the organically modified nanoclay with PAA‐co‐PAM copolymer was verified by FTIR, whereas the morphology of the composite was studied by Scanning Electron Microscopy (SEM). The water absorbency in deionized water and saline water of the synthesized nanohydrogels was measured by calculating their percentage swelling ratio. The effects of copolymerization, monomer ratio, clay content, and temperature on the water absorbency were studied. The results indicated a considerable increase in swelling ratio by proper monomer proportion and incorporation of optimum clay percentage into the copolymer matrix. It was found that the nanohydrogel acquired highest water absorbency with 2% clay loading. The reswelling ability and water retention capacity of the PAA‐co‐PAM hydrogel and PAA‐co‐PAM/clay nanohydrogel were also measured. The water absorbency was found to increase after each reswelling for which it may be useful as recyclable superabsorbent material. The results of water retention capacity of the nanohydrogel were also encouraging and find application in agriculture, especially in drought‐prone areas. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of a superabsorbent slow‐release fertilizer with sodium alginate and biochar

A novel hydrogel was synthesized through the graft copolymerization of acrylic acid (AA) and acrylamide (AM) onto sodium alginate with ammonium persulfate as the initiator, methylene bisacrylamide as the crosslinking agent, and calcium chloride as the precipitating agent. Rapeseed meal biochar made at 300 °C was also used. A series of graft copolymers with various molar ratio of AA to AM was prepared. The structures of the hydrogels were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The free absorbency and rate of release were investigated. The grafting efficiency increased as the concentration of AM increased. There was a considerable percentage of nitrogen in the graft copolymers, and the release rate of nitrogen from fertilizer in soil and water decreased with increasing concentration of AM. The water retention of soil without hydrogel remained at 63 and 53.4% on the 10th and 20th days, but with the hydrogels, it was above 70% even on the last day. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45966.     

Synthesis and water absorbency of polyampholytic hydrogels with antibacterial activity

Amphoteric terpolymers of acrylic acid (AA), acrylamide (AM), and N,N′‐dimethyl‐N‐ethylmeth‐acryloxylethylammoniumbromide (DMAEA‐EB) with varied compositions P[AA‐AM‐(DMAEA‐EB)] were synthesized by inverse suspension polymerization. The components of P[AA‐AM‐(DMAEA‐EB)] were verified by FTIR spectroscopy. The water absorption ability and antibacterial activity of the copolymer against Escherichia coli(E. coli) and Staphylococcus hyicus(S. hyicus) suspended in sterilized physiological saline were investigated. The introduction of  N⁺R₄ may increase the water absorbency of P[AA‐AM‐(DMAEA‐EB)] in some degree because of the excellent hydrophilicity of  N⁺R₄. The AA‐AM‐(DMAEA‐EB) hydrogels exhibited high antibacterial activity against bacteria tested. The process of adsorption between live bacteria cells and resins was at least partially reversible. A peak of antibacterial efficiency existed with increasing contact time. The resin killed 96.6% E. coli organisms and 90.3% S. hyicus organisms, respectively, within 30 min of contact at dosage of 0.1g. The concentration of DMAEA‐EB has a special effect on the antibacterial activity of the polyampholytic hydrogels, which is different from polycation. It was observed that the antibacterial activity of the resin with 2 mol % of DMAEA‐EB is superior to the copolymers tested with other compositions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and Swelling Behavior of Superabsorbents Cross-Linked with N-Maleyl Chitosan

A kind of superabsorbent based on the monomers maleic anhydride (MA) and acrylic acid (AA) was prepared by solution polymerization using ammonium peroxodisulfate (AP) and sodium bisulfite (NaHSO₃) as initiator, and N-maleyl chitosan (N-MACH) as cross-linker. Effects of process parameters such as the amount of cross-linker, mass ratio of MA to AA, and neutralization degree of AA on the water absorbency of superabsorbents are discussed. The results indicated the water absorbency of superabsorbents increased and then decreased with the increase of MA content, the amount of the N-MACH cross-linker, and the neutralization degree of AA. Under the optimal conditions, the water absorbency of superabsorbents could reach l560.42 g/g and 83.7 g/g in distilled water and in 0.9% NaCl solution, respectively. In addition, to enhance the water absorbency of superabsorbents in 0.9% NaCl solution, polyvinyl alcohol (PVA) was introduced as interpenetrating polymer in the network and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) was introduced as comonomer. It was proved that PVA and AMPS could effectively improve the water absorbency of superabsorbents both in distilled water and 0.9% NaCl solution.     

Acrylic superabsorbents: a meticulous investigation on copolymer composition and modification

In this paper, a six-factor and five-level orthogonal test was designed to investigate the influence factors on the solution absorbency of poly(acrylic acid-co-acrylamide) super absorbent resin (PAA/AM SAR). The results showed that the mass ratio of AA to AM played a predominant role in the synthesis of high-performance SAR. The copolymer composition $\overline{{F_{1} }}$ was 0.625 for the optimal absorbency copolymer. To control the copolymer composition, the reactivity ratios of AA and AM, which were 0.365 and 0.753, respectively, were determined at 60 °C using the integral method. The concentration of residual monomers was measured by ultraviolet spectrophotometry (UV) and gas chromatography (GC) methods. The copolymer composition was controlled by molar fraction of monomer AA $\mathop f\nolimits_{1}^{0}$  = 0.64, monomer conversion at 80–90 % and copolymerization at 60 °C. To improve the solution absorbency and water retention, PAA/AM SAR was modified by polyvinyl alcohol (PVA), cellulose and kaolin clay (KC). It is worth noting that the sample modified by the feed AA and AM PVA significantly increased the deionized water absorbency to 1,617 g/g and KC enhanced the 0.9 wt% NaCl absorbency to 189 g/g, which were higher than those of the commercial products. The chemical structure of copolymers was characterized by carbon-13 nuclear magnetic resonance spectroscopy (¹³C NMR) and fourier transform infrared spectrum (FTIR) and their pore morphology was investigated by scanning electron microscope (SEM).     

羽毛蛋白接枝聚丙烯酸-丙烯酰胺树脂的合成与吸水性能

以改性羽毛蛋白(MFP)、丙烯酸（AA）和丙烯酰胺(AM)为主要原料,N,N′-亚甲基双丙烯酰胺为交联剂,硫酸钾-亚硫酸氢钠为引发剂,采用溶液聚合法制备了羽毛蛋白接枝聚丙烯酸-丙烯酰胺高吸水树脂［P(MFP-g-AA/AM)］,并对其吸水性能及其影响因素进行了考察。结果表明,P(MFP-g-AA/AM)制备的最适宜工艺条件为W_AA∶W_AM=70∶30,丙烯酸的中和度为90％,W_MFP∶W_AA+AM=10%,W_initiator∶W_AA+AM=0.8%,W_crosslinker∶W_AA+AM=0.10%,反应温度为60℃,反应时间为2 h。在此条件下合成的P(MFP-g-AA/AM)树脂在去离子水中的饱和吸水倍率为578.0 g•g^-1,吸盐水（0.9％NaCl）倍率为78.6 g•g^-1,吸人工尿液倍率为75.1 g•g^-1,均高于羽毛蛋白接枝丙烯酸树脂。     

An amphoteric hydrogel: Synthesis and application as an internal curing agent of concrete

A new crosslinked amphoteric hydrogel (PAC) was synthesized and evaluated as an internal curing agent of concrete. PAC was prepared from acrylamide (AM) and 4‐(2‐((carboxylatomethyl)dimethylammonio)ethoxy)?4‐oxobut‐2‐enoate (CMD) through free‐radical polymerization by using ammonium persulfate (APS) as an initiator and methylene‐bisacrylamide (MBA) as a crosslinker. The structure of the prepared polymer was verified by the IR spectra. The effects of the polymerization variables on the swelling capacity of PAC were investigated. The water absorbency of PAC was found to increase with increasing CMD/AM ratio, reach a maximum value, and decrease afterword. Increase of either APS or MBA content decreased the water absorbency. The highest water absorbency of PAC hydrogel (P7) achieved in deionized water, 0.1M NaCl solutions and 0.1M CaCl₂ solutions, was 306 g/g, 32 g/g, and 22 g/g, respectively. Compared with a commercial acrylate‐based hydrogel 283HA, P7 was less sensitive to the existence of Ca²⁺ ions in cement pore solutions, and more effective in reducing the cracking tendency of cement pastes. Finally, mortars incorporated with proper amounts of P7 showed smaller drying shrinkage and higher compressive strength than that without hydrogel present. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42175.     

Synthesis and properties of silk sericin-<Emphasis Type="Italic">g</Emphasis>-poly(acrylic acid-co-acrylamide) superabsorbent hydrogel

A novel superabsorbent hydrogel has been synthesized with the crosslinking graft copolymerization of acrylic acid (AA) and acrylamide onto the chain of silk sericin. Potassium persulfate (KPS)–sodium sulfite (NaHSO₃) as redox initiation system and N,N′-methylenebisacrylamide (MBA) as crosslinker were used. The structure of the product characterized by Fourier transform infrared absorption spectroscopy and the surface morphology of the hydrogel were observed by scanning electron microscopy. The certain parameters of the graft copolymerization including the monomer, the initiator, the crosslinker concentration, neutralization degree of AA, reaction temperature, and time were systematically optimized to achieve a hydrogel with maximum swelling capacity (2150 g/g). The optimal conditions were initiator 8 mmol/L, MBA 2.5 mmol/L, neutralization degree of AA 75%, reaction temperature 55 °C, and time 6 h. The swelling ratio in salt solutions was also determined (in 0.9% NaCl aqueous solution: 98 g/g). In addition, the swelling capability of the hydrogel was measured in solutions with pH ranged from 1 to 13. The synthesized hydrogel exhibited a pH-dependent character. Water absorbency of the product in aqueous chloride salt solutions has the Na⁺ > Ca²⁺ > Mg²⁺ > Al³⁺ order in the investigated concentration.     

PVA/PAA-AM共混高吸水纤维的微观结构与吸液能力

丙烯酸(AA)、丙烯酰胺(AM)为单体,在聚乙烯醇(PVA)溶液中共聚,由聚合物溶液纺丝制备高吸水纤维。用扫描电子显微镜(SEM)观察了纤维微观结构,结果表明,高吸水纤维具有微相分离结构,纤维表面形貌和横截面形状随纤维组成变化。从吸水溶胀后经液氮冷阱干燥的纤维干凝胶的SEM照片,可以观察到纤维内部存在原纤间交联网络和大量各向异性分布的长形孔洞,证实纤维具有三维网络结构并且吸收过大量的水。随AM加入量的增加,纤维的吸液能力先上升后下降, w〔AM/(AA+AM+PVA)〕=3%时,纤维吸蒸馏水倍率为 243,吸ρ(NaCl) =9g/L的盐水溶液倍率为 58。研究表明,较多的AM会导致共混结构不相容性增加,吸水能力下降。     

A complex based on imidazole ionic liquid and copolymer of acrylamide and phenoxyacetamide modification for clay stabilizer

A complex system (AM/AA/APO‐EMIN) was obtained by poly (acrylamide‐co‐acrylic acid‐co‐N‐allyl‐2‐phenoxyacetamide) (AM/AA/APO) combining 1‐ethyl‐3‐methyl imidazolium tetrafluoroborate ([EMIM] [BF₄]) for clay stabilizer by using acrylamide (AM), acrylic acid (AA) and N‐allyl‐2‐phenoxyacetamide (APO), N‐methylimidazole, bromoethane, and sodium fluoroborate as raw materials. The complex solution exhibited excellent anti‐swelling rate (up to 94.5% at 10,000 mg/L), satisfying aging resistance (viscosity retention rate 84.2% after 15 days), and marked shear thinning behavior (viscosity retention rate 7.5% under 600 s^?1). From scanning electron microscope (SEM) images, a clear network structure appeared in AM/AA/APO‐EMIM solution. Compared with an existing poly (acrylamide‐co‐diallyl dimethyl ammonium chloride) clay stabilizer (HY‐201S), AM/AA/APO‐EMIN was less content and more effective to reduce the d‐spacing of sodium montmorillonite (Na‐MMT) from 19.1 Å to 15.7 Å. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41536.     

Synthesis of AA‐based superabsorbent interpenetrated with sodium PVA sulfate

An interpenetrating network of acrylic acid (AA)‐based superabsorbents and sodium PVA sulfate (SPS) were prepared by copolymerizing AA and N,N′‐methylene bisacrylamide as a crosslinking monomer in a solution of SPS with KPS, a radical initiator. The SPS was prepared through the sulfation of the hydroxyl groups of PVA with DMF‐SO₃ complex in DMSO. The AA‐based superabsorbent interpenetrated with SPS (SA‐IP‐SPS) showed superior properties such as higher water and saline absorbency, absorbency under load (AUL), and water retention value (WRV) compared with AA‐based superabsorbent due to the interpenetrated SPS. The maximum water and saline absorbency of SA‐IP‐SPS was 1753 and 125.6 g/g, respectively. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2525–2532, 2000