Novel salep‐based chelating hydrogel for heavy metal removal from aqueous solutions

A novel optimized chelating hydrogel was synthesized via graft copolymerization of acrylamide and 2‐hydroxyethyl methacrylate (as two‐dentate chelating co‐monomer) onto salep (a multicomponent polysaccharide obtained from dried tubers of certain natural terrestrial orchids) using N,N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. Reaction parameters (N,N′‐methylenebisacrylamide and ammonium persulfate amounts as well as acrylamide/2‐hydroxyethyl methacrylate weight ratio) affecting the water absorption of the chelating hydrogel were optimized using a systematic method to achieve a hydrogel with high swelling capacity as possible. Heavy metal ion adsorption capacity of the optimized hydrogel for metal ions [Cu (II), Pb (II), Cd (II), and Cr (III)] were investigated in aqueous media containing different concentrations of these ions (5–50 ppm). The results showed that the hydrogel have great potential for heavy metal removal from aqueous solutions. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy, and surface morphology study of the hydrogel was performed by scanning electron microscope. Copyright © 2016 John Wiley & Sons, Ltd.     

Study on superabsorbent composite—VII. Effects of organification of attapulgite on swelling behaviors of poly(acrylic acid‐co‐acrylamide)/sodium humate/organo‐attapulgite composite

A novel multifunctional superabsorbent composite from acrylic acid (AA), acrylamide (AM), sodium humate (SH) and organo‐attapulgite (organo‐APT), PAA‐AM/SH/organo‐APT, was synthesized by aqueous solution polymerization, using N,N′‐methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The organification of APT with hexadecyltrimethyl ammonium bromide (HDTMABr) was proved by FT‐IR. The effects of organo‐APT (HDTMA‐APT) content in the superabsorbent composite and organification degree of it on water absorbency of the superabsorbent composite were studied. The effects of incorporated HDTMA‐APT on swelling rate, water absorbency in various saline solutions and reswelling capability of the superabsorbent composite were also investigated. The results indicate that organification of APT had a remarkable influence on swelling behaviors of the superabsorbent composites. Comparing with the composite doped with APT, water absorbency for the composite incorporated with 10 wt% HDTMA‐APT was enhanced from 996 to 1282 g g^?1 in distilled water and from 63 to 68 g g^?1 in 0.9 wt% NaCl solution, respectively. The superabsorbent composite acquired its highest water absorbency when the organification degree of APT was 8.02 wt%. Water absorbency of the composites in various saline solutions decreased with the increasing concentration, especially for the multivalent cations. In addition, swelling rate and reswelling capability of the superabsorbent composite were also improved by introducing HDTMA‐APT into the composite compared with that of incorporating APT. Copyright © 2006 John Wiley & Sons, Ltd.     

Swelling behavior of poly{N‐[3‐(dimethylaminopropyl)] methacrylamide‐co‐acrylamide} hydrogels in aqueous solutions of surfactants

Temperature sensitive poly{N‐[3‐(dimethylaminopropyl)]methacrylamide‐co‐acrylamide} [P(DMAPMA‐co‐AAm)] hydrogels were prepared by the free‐radical crosslinking copolymerization of corresponding monomers in water with N,N‐methylenebisacrylamide as the crosslinker, ammonium persulfate as the initiator, and N,N,N′,N′‐tetramethylethylenediamine as the activator. The swelling equilibrium of the P(DMAPMA‐co‐AAm) hydrogels was investigated as a function of temperature in aqueous solutions of the anionic surfactant sodium dodecyl sulfate and the cationic surfactant dodecyltrimethylammonium bromide. In pure water, regardless of the amount of N,N‐methylenebisacrylamide, the P(DMAPMA‐co‐AAm) hydrogels showed a discontinuous phase transition between 30 and 36 °C. However, the transition temperature changed from discontinuous to continuous with the addition of surfactants; this was ascribed to the conversion of nonionic P(DMAPMA‐co‐AAm) hydrogels into polyelectrolyte hydrogels due to the binding of surfactants through hydrophobic interactions. Additionally, the concentrations of free sodium dodecyl sulfate and dodecyltrimethylammonium bromide ions were measured at different temperatures by conductometry, and it was found that the electric conductivity of the P(DMAPMA‐co‐AAm)–surfactant systems depended strongly on the swelling ratio; most notably, it changed drastically near the phase‐transition temperature of the P(DMAPMA‐co‐AAm) hydrogel. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1645–1652, 2006     

Graft copolymerization ofN‐vinyl‐pyrrolidone and acrylamide on cellulose derivatives: synthesis,characterization and study of their biological effect

Graft copolymers of carboxymethyl cellulose and hydroxyethyl cellulose with N‐vinyl‐2‐pyrrolidone and acrylamide have been synthesized by grafting copolymer of N‐vinyl‐2‐pyrrolidone and acrylamide onto a mixture of carboxymethyl cellulose and hydroxyethyl cellulose by a solution polymerization technique using a redox initiation system. The graft copolymers were characterized by ¹³C‐NMR spectroscopy and scanning electron microscopy. These graft copolymers have been tested for their biodegradability and biological activity. None of the graft copolymer solutions shows any microbial degradation up to 10 days. The reported results are evidence of the possibility of anti‐fungi effect. Copyright © 2002 John Wiley & Sons, Ltd.     

pH‐responsive ionic poly(N,N‐diethylaminoethyl methacrylate‐co‐N‐vinyl‐2‐pyrrolidone) hydrogels: Synthesis and swelling properties

A series of an ionic hydrogels composed of N,N‐diethylaminoethyl methacrylamide (DEAEMA), N‐vinyl‐2‐pyrrolidone (VP), and itaconic acid were synthesized by free‐radical cross‐linking copolymerization in water–ethanol mixture by using N,N‐methylenebis(acrylamide) as the cross‐linker, ammonium persulfate as the initiator, and N,N,N′,N′‐tetramethylenediamine as the activator. The swelling behaviors of these hydrogels were analyzed in buffer solutions at various pH. It was observed that the swelling behavior of cross‐linked ionic poly(N,N‐diethylaminoethyl methacrylamide‐co‐N‐vinyl‐2‐pyrrolidone) [P(DEAEMA/VP)] hydrogels at different pH agreed with the modified Flory–Rehner equation based on the affine network model and the ideal Donnan theory. The swelling process in buffer solutions at various pH was found to be Fickian‐type diffusion. The pH‐reversibility and on–off switching properties of the P(DEAEMA/VP) hydrogels may be considered as good candidate to design novel drug‐delivery system. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2819–2828, 2005     

Synthesis,characterization, and swelling behaviors of chitosan‐g‐poly(acrylic acid)/poly(vinyl alcohol) semi‐IPN superabsorbent hydrogels

A series of granulated semi‐interpenetrating polymer network (semi‐IPN) superabsorbent hydrogels composed of chitosan‐g‐poly(acrylic acid) (CTS‐g‐PAA) and poly(vinyl alcohol) (PVA) were prepared by solution polymerization using ammonium persulfate (APS) as an initiator and N,N′‐methylenebisacrylamide (MBA) as a crosslinker. The effects of reaction conditions such as the concentration of MBA, the weight ratio of AA to CTS, and the content of PVA on water absorbency were investigated. Infrared (IR) spectra and differential scanning calorimetry (DSC) analyses confirmed that AA had been grafted onto CTS backbone, and PVA semi‐interpenetrating into CTS‐g‐PAA networks. SEM analyses indicated that CTS‐g‐PAA/PVA has improved porous surface and PVA was uniformly dispersed in CTS‐g‐PAA network. The semi‐IPN hydrogel containing 10 wt% PVA shows the highest water absorbency of 353 and 53 g g^?1 in distilled water and 0.9 wt% NaCl solution, respectively. Swelling behaviors revealed that the introduction of PVA could improve the swelling rate and enhance the pH stability of the superabsorbent hydrogel. Copyright © 2009 John Wiley & Sons, Ltd.     

Lactose‐containing hydrogels for enzyme stabilization

A lactose‐containing monomer, N‐(2‐lactosylethyl)acrylamide, was synthesized and polymerized with N‐hydroxyethyl acrylamide and 1 wt % of N, N'‐methylenebis(acrylamide) and potassium persulfate as the initiator to produce hydrogels. The weight percent of N‐(2‐lactosylethyl)acrylamide were increased from 0 to 100% in increments of 10%. Hydrogels were successfully produced with up to 90 wt % of N‐(2‐lactosylethyl)acrylamide. Gelation was confirmed by inverted vial tests and rheology measurements. The as‐prepared hydrogels were used for papain stabilization against heat burden and papain that was loaded into hydrogels showed 45% more activity after heating as compared to papain that was heated without hydrogel stabilization. This hydrogel stabilization technique has potential applications in preserving enzyme activity. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2507–2514     

Synthesis and thermal properties of a novel lactose‐containing poly(N‐isopropylacrylamide‐co‐acrylamidolactamine) hydrogel

An improved, simple, and efficient method for the synthesis of lactose‐containing monomer acrylamidolactamine (LAM) has been reported. Free radical copolymerization of this monomer with N‐isopropylacrylamide (NIPAM) in the presence of the crosslinking reagent N,N′‐methylenebisacrylamide (BisA) (1.2 mol %) proceeded smoothly in an aqueous solution using potassium persulfate (KPS) and N,N,N′,N′‐tetramethylethylenediamine (TMEDA) as the initiating system and gave transparent hydrogels. Reactivity ratios were estimated from copolymerization reactions carried out in solution without BisA crosslinker and at low conversion, by using both linearization and nonlinearization methods. They were found to be r_LAM = 0.75 and r_NIPAM = 1.22. The swelling behavior of the hydrogels was studied by immersion of the hydrogels in deionized water at different temperatures. Equilibrium water uptake was increased when the LAM content was higher than 47 mol %, and reached ≈ 44‐fold with 100 mol % LAM at room temperature. Depending on the composition, the gels showed sharp swelling transitions with small changes in temperature. Differential scanning calorimetry (DSC) was used to characterize the swelling transition and the organization of water in the copolymer hydrogels. The amounts of freezable water in these hydrogels ranged from 81 to 89%, and was not correlated to the content of the sugar monomer. These gels have potential applications as biocompatible materials. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1393–1402, 1999     

Preparation,swelling behaviors and application of polyacrylamide/attapulgite superabsorbent composites

A series of superabsorbent composites, polyacrylamide/attapulgite (PAMA), were prepared from acrylamide (AM) and attapulgite micropowder in aqueous solution, using N,N′‐methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator and then saponified with sodium hydroxide solution. This paper focuses on swelling behaviors of the PAMA superabsorbent composites in various saline solutions. The results indicate that saline solutions can weaken the swelling abilities of the PAMA compsites greatly. Water absorbency of the PAMA composites with 20 and 40 wt% attapulgite in aqueous chloride salt solutions has the following order: Li⁺ = Na⁺ = K⁺, Mg²⁺ > Ca²⁺ = Ba²⁺ all through the range of concentration investigated. However, swelling properties of the composites are complicated in CuCl_2(aq), AlCl_3(aq) and FeCl_3(aq) solutions and are related to saline solutions concentration. The deswelling behavior of PAMA composites is more obvious in univalent chloride salt solutions than in divalent and trivalent ones. The influence of kind and valence of anions on swelling ability of the composites is limited and almost the same. Moreover, reswelling capability, practical water retention ability in sand soil of the composites and the effect of pH on water absorbency of the PAMA composites were investigated. The PAMA composite shows good water retention and reswelling ability in sand soil, and may be used as a recyclable water‐managing material for the renewal of arid and desert environment. Copyright © 2006 John Wiley & Sons, Ltd.     

Thermosensitive and control release behavior of poly (N‐isopropylacrylamide‐co‐acrylic acid) latex particles

In this work, poly(N‐isopropylacrylamide‐co‐acrylic acid) (poly(NIPAAm‐AA)) copolymer latex particles (microgels) were synthesized by the method of soapless emulsion polymerization. Poly(NIPAAm‐AA) copolymer microgels have the property of being thermosensitive. The concentration of acrylic acid (AA) and crosslinking agent N,N′‐methylenebisacrylamide were important factors to influence the lower critical solution temperature (LCST) of poly(NIPAAm‐AA) microgels. The effects of AA and crosslinking agent on the swelling behavior of poly(NIPAAm‐AA) microgels were also studied. The poly(NIPAAm‐AA) copolymer microgels were then used as a thermosensitive drug carrier to load caffeine. The effects of concentration of AA and crosslinking agent on the control release of caffeine were investigated. How the AA content and crosslinking agent influenced the morphology and LCST of the microgels was discussed in detail. The relationship of morphology, swelling, and control release behavior of these thermosensitive microgels was established. A new scheme was proposed to interpret the control release of the microgels with different morphological structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5734–5741, 2008     

Preparation,swelling, and stimuli‐responsive characteristics of superabsorbent nanocomposites based on carboxymethyl cellulose and rectorite

Utilization of naturally available raw materials for the fabrication of eco‐friendly functional materials has long been desired. In this work, a series of superabsorbent nanocomposites were prepared by radical solution copolymerization of sodium carboxymethyl cellulose (CMC), partially neutralized acrylic acid (NaA), and rectorite (REC) in the presence of initiator ammonium persulfate (APS) and crosslinker N,N'‐methylene‐bis‐acrylamide (MBA). The optimal reaction variables including the mass ratio of acrylic acid (AA) to CMC, MBA concentration, and REC content were explored. FTIR spectra confirmed that NaA had been grafted onto CMC and REC participated in polymerization. REC was exfoliated and uniformly dispersed in the CMC‐g‐PNaA matrix without agglomeration as shown by XRD, TEM, and SEM analysis. The thermal stability, swelling capabilities, and rate of the nanocomposites were improved after introducing REC, and the gel strength greatly depended on the concentration of crosslinker MBA. The nanocomposite showed excellent responsive properties and reversible On–Off switching characteristics in various saline, pH, and hydrophilic organic solvent/water solutions, which provided great possibility to extend the application domain of the superabsorbent nanocomposites such as drug delivery system. Copyright © 2010 John Wiley & Sons, Ltd.     

Double‐crosslinked reversible redox‐responsive hydrogels based on disulfide–thiol interchange

We present novel redox‐responsive hydrogels based on poly(N‐isopropylacrylamide) or poly(acrylamide), consisting of a reversible disulfide crosslinking agent N,N′‐bis(acryloyl)cystamine and a permanent crosslinking agent N,N′‐methylenebisacrylamide for microfluidic applications. The mechanism of swelling/deswelling behavior starts with the cleavage and reformation of disulfide bonds, leading to a change of crosslinking density and crosslinking points. Raman and ultraviolet‐visible spectroscopy confirm that conversion efficiency of thiol–disulfide interchange up to 99%. Rheological analysis reveals that the E modulus of hydrogel is dependent on the crosslinking density and can be repeatedly manipulated between high‐ and low‐stiffness states over at least 5 cycles without significant decrease. Kinetic studies showed that the mechanical strength of the gels changes as the redox reaction proceeds. This process is much faster than the autonomous diffusion in the hydrogel. Moreover, cooperative diffusion coefficient (D_coop) indicates that the swelling process of the hydrogel is affected by the reduction reaction. Finally, this reversibly switchable redox behavior of bulky hydrogel could be proven in microstructured hydrogel dots through short‐term photopatterning process. These hydrogel dots on glass substrates also showed the desired short response time on cyclic swelling and shrinking processes known from downsized hydrogel shapes. Such stimuli‐responsive hydrogels with redox‐sensitive crosslinkers open a new pathway in exchanging analytes for sensing and separating in microfluidics applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2590–2601     

Preparation and characterization of cellulose acetate‐coated compound fertilizer with controlled‐release and water‐retention

A novel cellulose acetate‐coated compound fertilizer with controlled‐release and water‐retention (CAFCW) was prepared, which possessed the three‐layer structure. Its core was water‐soluble compound fertilizer granular, the inner coating was cellulose acetate (CA), and the outer coating was poly(acrylic acid‐co‐acrylamide)/unexpanded vermiculite (P(AA‐co‐AM)/UVMT) superabsorbent composite. The effects of the amount of acrylamide, crosslinker, initiator, degree of neutralization of acrylic acid (AA), and unexpanded vermiculite concentration on water absorbency were investigated and optimized. The water absorbency of CAFCW was 72 times its own weight if it was allowed to swell in tap water at room temperature for 90 min. Element analysis and atomic absorption spectrophotometer results showed that the product contained 11% nitrogen, 6% phosphorus (shown by P₂O₅), 9% potassium (shown by K₂O), 1% calcium (shown by CaO), and 0.4% magnesium (shown by MgO). Swelling rate, slow‐release, and water‐retention properties of CAFCW were also investigated. This product with good controlled‐release and water‐retention capacity, being degradable in soil and environmentally friendly, could be especially useful in agricultural and horticultural applications. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and characterization of pH‐sensitive PAMPS/PVP nanogels in aqueous media

A novel method for preparing poly (2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS) and poly (vinylpyrrolidone) (PVP) complex nanogels in PVP aqueous solution is discussed in this paper. The PAMPS/PVP complex nanogels were prepared via polymerization of 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) monomer in the presence of PVP nanoparticles which formed in water/acetone cosolvent in presence of N, N′‐methylenebisacrylamide (MBA) as a crosslinker, N, N, N′, N′‐tetramethylethylenediamine (TEMED) and potassium peroxydisulfate (KPS) as redox initiator system. The results of FTIR and ¹H NMR spectra indicated that the compositions of PAMPS/PVP are consistent with the designed structure. TEM micrographs proved that PAMPS/PVP nanogels possess the spherical morphology before and after swelling. These PAMPS/PVP nanogels exhibited pH‐induced phase transition due to protonation of PAMPS chains. The properties of PAMPS/PVP nanogels indicate that PAMPS/PVP nanogels can be developed into a pH‐controlled drug delivery system. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of dual responsive cyclotriphosphazene‐based IPN hydrogels for controlled release of chemotherapeutic agent

Dual responsive cyclotriphosphazene (CTP)‐based hydrogels have been synthesized for a controlled release of FU, a hydrophilic drugs. These hydrogels composed of mono (methacryloyl‐2‐ethoxy)‐pentakis(N¹,N¹‐dimethylpropane‐1,3‐diamino)‐cyclotriphosphazene (HEMA (DMPDA)₅CP), acryl amide and pectin were synthesized by free radical polymerization method using methylenebisacrylamide cross linker. The CTP hydrogels were characterized to understand the structure, drug nature in the network and morphology by FTIR, DSC, XRD and SEM, respectively. In this paper, the swelling (dynamic and equilibrium) properties of cyclotriphosphazene hydrogels were investigated, showing dual (pH and thermo) responsiveness and large variation in the swelling capacity. Based on these results the structural parameters of the hydrogel networks such as the average molecular weight between cross‐links (M_c) and polymer–solvent interaction parameter (χ) were determined. The CTP hydrogels has high FU loading efficiency 65 ± 0.5. In‐vitro FU release of these hydrogels was controlled for about 24 hr also hydrogel showed a distinct initial burst. The CTP hydrogels are bearing both hydrophilic groups of pectin and hydrophobic groups of CTP exhibited dual responsive behaviors with pH and temperature. Copyright © 2015 John Wiley & Sons, Ltd.     

Novel adsorptive materials by adenosine 5ʹ‐triphosphate imprinted‐polymer over the surface of polystyrene nanospheres for selective separation of adenosine 5ʹ‐triphosphate biomarker from urine

In this study, we have developed a method to assess adenosine 5?‐triphosphate by adsorptive extraction using surface adenosine 5′‐triphosphate‐imprinted polymer over polystyrene nanoparticles (412 ± 16 nm) for selective recognition/separation from urine. Molecularly imprinted polymer was synthesized by emulsion copolymerization reaction using adenosine 5′‐triphosphate as a template, functional monomers (methacrylic acid, N‐isopropyl acrylamide, and dimethylamino ethylmethacrylate) and a crosslinker, methylenebisacrylamide. The binding capacities of imprinted and non‐imprinted polymers were measured using high‐performance liquid chromatography with UV detection with a detection limit of 1.6 ± 0.02 µM of adenosine 5′‐triphosphate in the urine. High binding affinity (Q_MIP, 42.65 µmol/g), and high selectivity and specificity to adenosine 5′‐triphosphate compared to other competitive nucleotides including adenosine 5?‐diphosphate, adenosine 5?‐monophosphate, and analogs such as adenosine, adenine, uridine, uric acid, and creatinine were observed. The imprinting efficiency of imprinted polymer is 2.11 for urine (Q_MIP, 100.3 µmol/g) and 2.51 for synthetic urine (Q_MIP, 48.5 µmol/g). The extraction protocol was successfully applied to the direct extraction of adenosine 5′‐triphosphate from spiked human urine indicating that this synthesized molecularly imprinted polymer allowed adenosine 5′‐triphosphate to be preconcentrated while simultaneously interfering compounds were removed from the matrix. These submicron imprinted polymers over nano polystyrene spheres have a potential in the pharmaceutical industries and clinical analysis applications.     

Modified carrageenan. 5. Preparation,swelling behavior,salt‐ and pH‐sensitivity of partially hydrolyzed crosslinked carrageenan‐graft‐polymethacrylamide superabsorbent hydrogel

The polysaccharide, kappa‐carrageenan (κC) was chemically modified to achieve a novel superabsorbent hydrogel via graft copolymerization of methacrylamide (MAM) onto the substrate followed by alkaline hydrolysis. Ammonium persulfate (APS) and N,N′‐methylene bisacrylamide (MBA) were used as a free‐radical initiator and a crosslinker, respectively. The saponification reaction was carried out using sodium hydroxide aqueous solution. Either κC‐g‐PMAM or hydrolyzed κC‐g‐PMAM (PMAM: polymethacrylamide) was characterized by FT‐IR spectroscopy. The effect of grafting variables (i.e. concentration of MBA, MAM, and APS) and alkaline hydrolysis conditions (i.e. NaOH concentration, hydrolysis time and temperature) were systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The swelling capacity of these hydrogels was also measured in various salt solutions. Results indicated that the swelling ratios decreased with an increase in the ionic strength of the salt solutions. This behavior can be attributed to charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. Absorbency of superabsorbing hydrogels was examined in buffer solutions with pH range 1–13. Also, the pH reversibility and on–off switching behavior, at pH values 3.0 and 8.0, makes the synthesized hydrogels good candidates for controlled delivery of bioactive agents. Finally, swelling kinetics in distilled water and various salt solutions was preliminary investigated. Results showed that the swelling in water was faster than in saline solutions. Copyright © 2004 John Wiley & Sons, Ltd.     

Conducting hydrogels based on semi‐interpenetrating networks of polyaniline in poly(acrylamide‐co‐itaconic acid) matrix: synthesis and characterization

In this work, acrylamide/itaconic acid copolymeric hydrogels are prepared by free radical polymerization initiated by redox initiators of potassium persulfate and N ,N ,N ′,N ′‐tetramethyl ethylene diamine; N ,N ′methylene bisacrylamide was employed as a crosslinking agent. Aniline monomer was absorbed in the network of poly(acrylamide‐co‐itaconic acid) P(AAm‐co‐IA) hydrogel and followed by gamma radiation induced polymerization at room temperature. The novel semi‐interpenetrating network was comprised of linear polyaniline immersed in P(AAm‐co‐IA) matrix. Electrical conductivity of the hydrogels was measured using four‐probe technique. The conductivities for the prepared hydrogels are found to increase from 5.5 × 10^?7 S cm^?1 for P(AAm‐co‐IA) alone to 4.4 × 10^?3 S cm^?1 for semi‐interpenetrating polymer network P(AAm‐co‐IA)/polyaniline. Thus, a new composite hydrogel with good conductive properties also displaying enhanced mechanical strength and pH sensitivity was prepared. Copyright © 2017 John Wiley & Sons, Ltd.     

Property and Application of BACy‐Based Functional Hydrogels

Conventional polyacrylamide hydrogels prepared from the free radical polymerization between acrylamide and N,N′‐methylenebisacrylamide (NMBA) have been frequently used in the biochemical technique like the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) to resolve protein mixtures. In this study, we have prepared an alternative polyacrylamide hydrogel from the cross‐linking of acrylamide and N,N′‐bisacrylylcystamine (BACy). In addition, we have compared the BACy‐based hydrogel with the NMBA‐based polyacrylamide hydrogel for their physical properties such as swelling ratio, shear modulus, crosslink density and morphology. Moreover, we further determined whether BACy‐based polyacrylamide hydrogel could be applied to SDS‐PAGE and proteomics research. The results showed that this type of hydrogel is capable of separating proteins and facilitates further in‐gel protein digestion and the following protein identifications by mass spectrometry. In summary, our study provides a basis for the putative application of BACy‐based hydrogels.     

Dye removal by a novel hydrogel‐clay nanocomposite with enhanced swelling properties

Acrylamide (AAm)‐2‐acrylamide‐2‐methylpropanesulfonic acid sodium salt (AMPSNa) hydrogel and AAm‐AMPSNa/clay hydrogel nanocomposite having 10 w% clay was prepared by in situ copolymerization in aqueous solution in the presence of a crosslinking agent (N,N′‐methylenebisacrylamide (NMBA)). Swelling properties and kinetics of the hydrogel samples were investigated in water and aqueous solutions of the Safranine‐T (ST) and Brilliant Cresyl Blue (BCB) dyes. The swelling and diffusion parameters were also calculated in water and dye solutions. It was observed that the AAm‐AMPSNa/clay hydrogel nanocomposite exhibits improved swelling capacity compared with the AAm‐AMPSNa hydrogel. It was also found that the diffusion mechanisms show non‐Fickian character. Adsorption properties of the hydrogel samples in the aqueous solution of ST and BCB dyes were also investigated. Clay incorporation into the hydrogel structure increased not only the adsorption capacity but also the adsorption rate. Adsorption capacity values of the hydrogel nanocomposite were found to be 484.2 and 494.2 mg g^?1 for the ST and BCB dyes, respectively. It was seen that the adsorption of dyes by the hydrogel nanocomposite completed in 10 min while the AAm‐AMPSNa hydrogel adsorbed dyes approximately in 90 min. Adsorption data of the samples were modelled by the pseudo‐first‐order and pseudo‐second‐order kinetic equations in order to investigate dye adsorption mechanism. It was found that the adsorption kinetics of hydrogel nanocomposite followed a pseudo‐second‐order model. Equilibrium isotherms were analyzed using the Langmuir and Freundlich isotherms. It was seen that the Langmuir model fits the adsorption data better than the Freundlich model. Copyright © 2008 John Wiley & Sons, Ltd.