Preparation and characterization of nanocomposite hydrogels based on polyacrylamide for enhanced oil recovery applications

In the present work, attempts have been made to prepare nanocomposite type of hydrogels (NC gels) by crosslinking the polyacrylamide/montmorillonite (Na‐MMT) clay aqueous solutions with chromium (III). The X‐ray diffraction patterns of the NC gels exhibited a significant increase in d₀₀₁ spacing between the clay layers, indicating the formation of intercalated as well as exfoliated type of morphology. Exfoliation of the clay layers through out the gel network was found to be predominated, which evidences the high interaction between the polyacrylamide segments and montmorillonite layers. Gelation time as well as variation of viscoelastic parameters such as storage modulus (G′) of the gel network during gelation process at 75°C was studied and followed by rheomechanical spectroscopy (RMS). The NC gels prepared with lower crosslinker concentration showed higher strength and elastic modulus compared with the similar but unfilled polyacrylamide gel. This distinct characteristic of the NC gels yields a gel network structure with high resistance towards syneresis at high temperature in the presence of the oil reservoir formation water. The effects of the composition, such as clay content, crosslinker concentration, and also water salinity upon the gelation rate, gel strength as well as rate of syneresis have been investigated. To optimize the injectivity of the intercalated polyacrylamide solution before the onset of gelation with the gel strength of the final developed gel, sodium lactate was employed as retarder. This was found to be effective to balance these two characteristics of the NC gels, which are aimed to be used for water shut‐off and as profile modifier in enhanced oil recovery (EOR) process during water flooding process. The nanocomposite gels showed much more elasticity and extensibility at low crosslinker concentration compared with the similar but unfilled gel, which makes the NC gels suitable as an in‐depth profile modifier, and also as an oil displacing agent in the heterogeneous oil reservoir in chemical EOR. Effects of the clay content on the thermal stability of the gel network have also been investigated by thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) has been performed upon the NC‐gel samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2096–2103, 2006     

Preparation and characterization of elastomer‐based nanocomposite gels using an unique latex blending technique

Nanocomposite (NC) gels based on natural rubber (NR) and styrene butadiene rubber (SBR) were prepared by using a unique latex blending technique. These NC gels were prepared by first blending the water swollen unmodified montmorillonite clay (Na⁺‐MMT) suspension into the respective latices followed by prevulcanization to generate crosslinked nanogels. Use of water assisted fully delaminated Na⁺‐MMT suspension resulted in predominantly exfoliated morphology in the NC gels, as revealed by X‐ray diffraction study and transmission electron microscopy. Addition of Na⁺‐MMT significantly improved various physical, mechanical and thermal properties of these NC gels. For example, 6 phr of Na⁺‐MMT loaded NR based NC gels registered 54% and 200% increase in tensile strength and Young's modulus, respectively, compared to the unfilled NR gels. SBR based NC gels also showed similar level of improvement in mechanical properties. Mechanical properties of NC gels prepared using this route were also compared with the NC gels prepared by co‐coagulation and conventional curing technique and found to be superior. In the case of dynamic mechanical properties, NC gels showed higher glass transition temperatures along with a concomitant increase in storage moduli, compared to the unfilled gels. These Na⁺‐MMT reinforced NC gels also exhibited markedly improved thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Absorption characterization of Ca2+, Na+, and K+ on irradiation crosslinked carboxymethyl sago pulp hydrogel

Hydrogel of carboxymethyl sago pulp (CMSP) of various degree of substitution (DS) was prepared by electron beam irradiation of various radiation doses. The CMSP hydrogels were subjected to swelling in different ionic strength solutions of KCl, NaCl, and CaCl₂. The CMSP hydrogels, due to its polyelectrolyte nature, were found to be highly sensitive to ionic strength of the medium. All the CMSP hydrogels showed the absorption of K⁺ and Ca²⁺ increases with the increase in the concentrations of the respective cation solutions. The cation absorption also decreases with DS and % gel fraction (%GF) of the CMSP hydrogels. Subjecting the CMSP hydrogels in NaCl results in deswelling and releases Na⁺ to swelling medium where the Na⁺ release increases with the increase of DS and %GF. The sorption capacity depends on the extent of crosslinking and decreases with the increase in the extent of crosslinking. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Study on superabsorbent composite. XX. Effects of cation‐exchanged montmorillonite on swelling properties of superabsorbent composite containing sodium humate

In this work, the effects of different cation‐exchanged montmorillonite on water absorbency of poly(acrylic acid‐co‐acrylamide)/montmorillonite/sodium humate (PAA‐AM/MMT/SH) superabsorbent composite were systematically investigated under the same preparation conditions. The superabsorbents doped with different cation‐exchanged montmorillonite were characterized by Fourier‐transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy technologies. Swelling behaviors of developing superabsorbent composite in various cationic saline solutions (NaCl, CaCl₂, and FeCl₃) were also investigated. The water absorbencies of superabsorbent composite with 20 wt% MMT and 30 wt% SH are 638, 723, 682, and 363 g g⁻¹ in distilled water for incorporating natural Na⁺‐MMT, Li⁺‐exchanged MMT, Ca²⁺‐exchanged MMT, and Al³⁺‐exchanged MMT, respectively. The results showed that the cation‐exchange process had some obvious influences on final water absorbency of superabsorbent composite. NaCl, CaCl₂, and FeCl₃ solutions did not alter the swelling characteristics of the superabsorbent materials at a concentration of less than 0.01 mM, however, a concentration of greater than 0.1 mM caused a collapse in the swelling curves. The excellent swelling‐reswelling‐swelling behavior and lower swelling rate testified that Al³⁺‐exchanged MMT can act as an assistant crosslinker in the polymeric network. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Thermosensitive and ampholytic hydrogels for salt solution

A series of N‐isopropylacrylamide/[[3‐(methacryloylamino)propyl]dimethy(3‐sulfopropyl)ammonium hydroxide] (NIPAAm/MPSA) copolymer hydrogels were prepared with various compositions. Swelling of the hydrogels in water, aqueous NaCl, KCl, CaCl₂, and MgCl₂ solutions was studied. NIPAAm/MPSA hydrogels have a higher degree of swelling in water and salt solutions than that of poly(N‐isopropylacrylamide) (PNIPAAm). Also, NIPAAm/MPSA hydrogels are more salt resistant when deswelling in salt solutions. For <7 mol % MPSA, the formed hydrogels retain both temperature reversibility and high swelling. A higher content of MPSA (>11 mol %) leads to better salt resistance but a decrease in thermosensitivity. The swelling of NIPAAm/MPSA hydrogel in 0.05M NaCl is non‐Fickian. In NaCl and KCl aqueous solutions, the zwitterionic hydrogels do not show obvious antipolyelectrolyte swelling behavior, whereas in divalent salt CaCl₂ and MgCl₂ solutions, the swelling ability of NIPAAm/MPSA hydrogels is enhanced at low salt concentration, then decreases with further increase in salt concentration. The lower critical solution temperatures of NIPAAm/MPSA hydrogels are also affected by concentrated salt solution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2032–2037, 2003     

Effect of montmorillonite on the properties of thermosensitive poly(N‐isopropylacrylamide) composite hydrogels

Thermosensitive composite hydrogels containing various amounts of sodium montmorillonite (NaMM) and poly(N‐isopropylacrylamide) (pNIPAAm) were synthesized. Their equilibrium degree of swelling (DS) was measured in NaCl solutions of different ionic strength and at various temperatures. The DS decreased when increasing the clay content and no substantial shift in the phase transition temperature was noticed. The composite hydrogels investigated had a NaMM content ranging between 1.0 and 5.7 wt % (in 0.1M NaCl at 25°C). A considerable enhancement in the response to thermal stimuli was observed for NaMM contents >2–3 wt %. It is suggested that when the NaMM concentration approaches a critical value, the clay platelets can inhibit the formation of the hydrophobic skin layer that hinders shrinking in conventional pNIPAAm hydrogels. The effect of montmorillonite on the mechanical properties of the hydrogels was investigated by uniaxial compression tests, which showed that the modulus increases with the NaMM content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1964–1971, 2004     

Nanoclay dispersion in a miscible blend: an assessment through rheological analysis

In this study, miscible polymer blend nanocomposite of Poly(ethylene oxide)/Poly(methyl methacrylate), (PEO/PMMA), with sodium montmorillonite (Na⁺-MMT) clay were prepared at a constant concentration of nanoparticles via different solution intercalation methods. The resultant nanocomposites possess different structure and dispersion of Na⁺-MMT clays which are assessed through a combination of transmission electron microscopy (TEM) and X-ray diffraction (XRD). The rheology of the neat blend and two different layered silicate nanocomposites were investigated using linear viscoelastic measurements with a parallel plate rheometry at small strain amplitudes. It was found that regardless of the extent of dispersion, the storage and loss modulus increased by incorporating the nanoparticles into the matrix of PEO/PMMA. Moreover, at low frequencies the rheological response of the nanocomposite in which layered silicates benefit from a better dispersion becomes relatively invariant with frequency and represents a mediocre solid-like behavior in comparison to the nanocomposite in which the nanoparticles are intercalated or agglomerated.     

Swelling behavior of poly(acrylamide)/clay nanocomposite hydrogels in acrylamide aqueous solution

The swelling behaviors of poly(acrylamide) (PAAm)/clay nanocomposite hydrogels (hereinafter abbreviated as NC gels) in acrylamide (AAm) aqueous solution have been investigated. As‐prepared PAAm/clay hydrogels (S‐M gels) were posttreated by immersing them in AAm aqueous solution. It was found that the swelling ratio of the NC gels increased greatly when the concentration of the solution is below a critical concentration (c*), whereas the gels were disintegrated in the solution when the concentration of the solution is above the c*. Some disc‐like particles were found in the AAm solution accompanying with the unusual swelling behaviors. This unusual swelling behavior is resulted from the change of network structure of the NC gels in AAm aqueous solution, which was further convinced by transmission electron microscopy and element analyses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of charged linear and crosslinked maleic diester polymers with electron‐beam irradiation

Series of maleic mono‐ and diester monomers have been prepared by esterification of maleic anhydride with poly(ethylene glycol) having different molecular weights, and with n‐dodecyl alcohol. These monomers were copolymerized with 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) using different dose rates of electron‐beam irradiation ranging from 40 to 150 kGy. The synthesized copolymers were characterized by IR and ¹H NMR analysis. Their aggregation behaviour and viscometric properties in aqueous solutions were investigated. The crosslinked copolymers were prepared in aqueous acidic solutions at pH 1 or in the presence of 1% of N,N‐methylene bisacrylamide (MBA) as crosslinking agent. The final equilibrium water content and swelling capacities for the prepared hydrogels were determined in aqueous solutions at pH = 1, 6.8 and 12 at 298 K. Swelling equilibria for the prepared hydrogels were carried out in aqueous solutions of NaCl, KCl, CaCl₂, Na₂SO₄, K₂SO₄ and CaSO₄ at concentrations ranging from 1 × 10^?6 to 2 M at 298 K. © 2003 Society of Chemical Industry     

Preparation and characterization of sodium alginate/poly(<Emphasis Type="Italic">N</Emphasis>-isopropylacrylamide)/clay semi-IPN magnetic hydrogels

pH- and temperature-responsive semi-interpenetrating magnetic nanocomposite hydrogels (NC hydrogels) were prepared by using linear sodium alginate (SA), poly(N-isopropylacrylamide) (PNIPAM) and Fe₃O₄ nanoparticles with inorganic clay as an effective multifunctional cross-linker. The effects of cross-linker and SA contents on various physical properties were investigated. The NC hydrogels exhibited a volume phase transition temperature (VPTT) around 32 °C with no significant deviation from the conventional chemically cross-linked PNIPAM hydrogels (OR hydrogels). The swelling ratios of NC hydrogels were much larger than those of OR hydrogels. Moreover, the swelling ratios of NC hydrogels gradually decreased with increasing the contents of clay and increased with increasing the contents of SA. The pH sensitivity of NC hydrogels was evident below their VPTT. The NC hydrogels had a much better mechanical property than the OR hydrogels. The results showed that the incorporation of clay did not affect the saturation magnetization of the hydrogels.     

The effect of physiologically relevant additives on the rheological properties of concentrated Pluronic copolymer gels

The high concentration triblock copolymer poly(ethylene oxide)₉₉-poly(propylene oxide)₆₉-poly(ethylene oxide)₉₉ (Pluronic F127) aqueous solutions with the addition of different components commonly used in physiologically relevant applications were characterized by rheological measurements, differential scanning calorimetry (DSC) and small angle X-ray/neutron scattering. The sol-gel transition temperature, as well as the storage modulus of the F127 solution depend both on the concentration of polymer and of clay. Above the gel transition, the storage modulus of the solutions increased with clay concentration. Yield strain is independent of polymer and clay concentrations. Two different kinds of inorganic salts, sodium chloride (NaCl) and calcium chloride (CaCl₂) were added into the polymer and polymer-clay solutions. The sol-gel transition temperature decreased noticeably, but the storage modulus decreased only a small amount with increasing concentration of inorganic salts. Addition of salts to polymer-clay solutions resulted in precipitation of the clays which decreased the modulus. No effect on the mechanical properties was observed with the addition of common serum proteins. However, addition of 0.5-10% glucose decreased the transition temperature between 3° and 7°, without significantly affecting the modulus. The depression of the transition temperature by glucose was similar to that found with salts and indicated that the mechanism, namely competition for water, may be similar.     

Promoted cell proliferation and mechanical relaxation of nanocomposite hydrogels prepared in cell culture medium

Nanocomposite hydrogels (NC gels) were synthesized through in situ polymerization of N-isopropylacrylamide (NIPAm) in the hectorite clay suspension made from cell culture medium Dulbecco’s modified Eagle medium (DMEM). Cell cultured on these NC gels (D-NC gels) surface proliferated faster compared with that on the NC gels synthesized in water due to the nutrients in the D-NC gels. Cells attached and proliferated faster on the D-NC gels with higher modulus. In addition, cell sheets with good viability spontaneously detached from the gel surface by lowering temperature. Their tensile elongation at break was higher than 7 and the true strength σ_true was up to 800 kPa. The stress–strain curves of the D-NC gels were described quantitatively with the Mooney–Rivlin equation. A stretched exponential stress equation was adopted to express the stress relaxation of the D-NC gels with an average relaxation time τ (～10² s) estimated from data fitting, showing a broad distribution (polydispersity k ～ 0.4). The τ value, which was used in simulation for the tensile creep compliance of the D-NC gels, became shorter with increasing clay concentration due to the decrease in the network chain length. The relaxation process was similar to the natural articular cartilage. This work provides a facile way to produce hydrogels with improved cell compatibility and satisfactory mechanical properties for biomedical applications.     

Rheological and thermal stability of novel weak gels based on sulfonated polyacrylamide/scleroglucan/chromium triacetate

The present study deals with weak gels based on sulfonated polyacrylamide (SPA)/scleroglucan (SC)/Cr³⁺ with an exceptional thermal stability in electrolyte media. The rheological results showed that on increasing the SC concentration the shear viscosity and storage modulus of the SPA/SC/Cr³⁺ system were increased and the dependence of the storage modulus on frequency became weaker. The yield stress of the SPA/SC/Cr³⁺ system was higher than that of the corresponding SPA/SC system. The thermochemical stability increased with increasing relaxation time. The SPA/SC/Cr³⁺ semi‐interpenetrating network exhibited the lowest viscosity loss in electrolyte media; therefore this system may be a potential candidate for enhanced oil recovery applications. © 2016 Society of Chemical Industry     

Synthesis of montmorillonite-modified acrylic impact modifiers and toughening of poly(vinyl chloride)

A series of Na-montmorillonite (Na⁺-MMT) modified acrylic impact modifiers (mAIM) were prepared by seeded emulsion polymerization. These mAIM modifiers were characterized by XRD. A 0.24?nm of increased interlayer distance of Na⁺-MMT was an indication of polymer chains intercalation within interlayer spacing. The notched Izod impact tests proved that the impact strength of the PVC/AIM composites prepared by melt blending was 43?J/m, markedly higher than the impact strength of pure PVC. Furthermore, with increasing content of AIM, the composites exhibited changes from brittle fracture to ductile fracture, with the impact strength increasing from 200 to about 1,000?J/m. The impact strength of PVC/mAIM also showed the same trend, although there were drops in some values. The impact strength of PVC/mAIM composites decreased with the increases in Na⁺-MMT content, but the yield strength and modulus of the composites increased with higher Na⁺-MMT content. The result also showed that the tensile strength of mAIM with 2 wt?% Na⁺-MMT is lower than that of mAIM with 0.8 and 1 wt?% contents, but still sufficiently large in comparison to the tensile strength of mAIM with 0 wt?% Na⁺-MMT. The dynamic mechanical analysis (DMA) result showed that the glass transition temperature (T _g) of mAIM did not show obvious changes and the elasticity of mAIM was reduced with the additional Na⁺-MMT content.     

Synthesis and characterization of pH-sensitive and biodegradable hydrogels prepared by γ irradiation using microbial poly(γ-glutamic acid) and poly(ϵ-lysine)

Poly(γ-glutamic acid) (PGA) and poly(?-lysine) (PL) solutions were used as components to prepare mixed hydrogels by γ irradiation. A PGA and PL mixed solution was crosslinked to form a hydrogel with specific water content (weight of absorbed water/weight of dry gel) of 10–100 when the 5 wt % solution of mixed polymer was exposed to γ radiation of 87 kGy dosage under N₂ atmosphere. The specific water content increased with increasing PGA content of the PGA/PL mixed gel. The influence of pH and salt concentration on equilibrium swelling was studied. A characteristic pH-sensitive swelling behavior was obtained using compositional changes of PGA and PL in the gel. PGA/PL 50/50 wt % mixed gel swelling in acid (pH < 4.0) and alkaline (pH > 6.0) conditions and was deswelled between pH 4.0 and 6.0 due to the ionic composition changes of the gel network. With an increase in the ratio of PGA to PL, the hydrogels showed increasing sensitivity to salt solutions (NaCl, Na₂SO₄, and CaCl₂). In addition, degradation of PGA/PL gel by protease produced from Aspergillus oryzae was investigated at 40°C and pH 7.0. PL gel was degraded completely within 2 days. An increase in the ratio of PAG in the PGA/PL mixed gel led to a decrease in the degree of degradation as expected. Some subtle degradation changes were found in the 50/50 and 80/20 wt % (PGA/PL) gels that were degraded by only 3.5 and 3.8% by protease, respectively. © 1995 John Wiley & Sons, Inc.     

Poly(acrylamide/laponite) nanocomposite hydrogels: Swelling and cationic dye adsorption properties

Super adsorbent polyacrylamide (PAAm)/nanoclay (laponite, Lap) hydrogels were prepared by in situ free radical polymerization of AAm in an aqueous solution with clay as a crosslinker. The swelling properties and water‐soluble cationic dye adsorption behaviors of the PAAm/laponite (PAAm/Lap) nanocomposite (NC) hydrogels were investigated. The parameters of swelling and diffusion of water in dye solutions were evaluated for the PAAm/Lap NC hydrogels. The adsorption behavior of the monovalent cationic dyes such as Basic Blue 12 (BB 12), Basic Blue 9 (BB 9), and Basic Violet 1 (BV 1), were studied on the NC hydrogels. The effects of the clay content of the hydrogel on its cationic dye uptake behavior were studied. The adsorption studies indicated that the rates of dye uptake by the NC hydrogels increased in the following order: BB 9 > BB 12 > BV 1. This order is similar to the swelling results of the PAAm/Lap NC hydrogel in the dye solutions. The equilibrium uptakes of the different dyes by the PAAm/Lap NC hydrogel were nearly the same. In the dye absorption studies, S‐type adsorption in the Giles classification system was found for the BB 12 and BV 1 dyes, whereas L ‐type was observed for the BB 9 dye. After the heat treatment of PAAm/Lap, the rate of dye uptake and equilibrium dye uptake were increased. The NC hydrogels may be considered as a good candidate for environmental applications to retain more water and to remove dyes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Comparative studies on the corrosion protection effect of DBSA-doped polyaniline prepared from in situ emulsion polymerization in the presence of hydrophilic Na-MMT and organophilic organo-MMT clay platelets

A series of polyaniline (PANI)/Na⁺-montmorillonite (MMT) clay and PANI/organo-MMT nanocomposite materials have been successfully prepared by in situ emulsion polymerization in the presence of inorganic nanolayers of hydrophilic Na⁺-MMT clay or organophilic organo-MMT clay with DBSA and KPS as surfactant and initiator, respectively. The as-synthesized Na⁺-PCN and organo-PCN materials were characterized and compared by Fourier transformation infrared (FTIR) spectroscopy, wide-angle powder X-ray diffraction (XRD) and transmission electron microscopy (TEM).Na⁺-PCN materials in the form of coatings with low loading of Na⁺-MMT clay (e.g., 3 wt.%, CLAN3) on cold-rolled steel (CRS) were found much superior in corrosion protection over those of organo-PCN materials with same clay loading based on a series of electrochemical measurements of corrosion potential, polarization resistance, corrosion current and impedance spectroscopy in 5 wt.% aqueous NaCl electrolyte. The molecular weights of PANI extracted from PCN materials and neat PANI were determined by gel permeation chromatography (GPC) with NMP as eluant. Effects of material composition on the gas permeability, optical properties and electrical conductivity of neat PANI and a series of PCN materials, in the form of free-standing film, solution and powder-pressed pellet, were also studied by gas permeability analyzer (GPA), ultraviolet-vis spectra and four-point probe technique, respectively.     

Unusual swelling behavior of polymer-clay nanocomposite hydrogels

The swelling behavior and the elastic properties of nanocomposite hydrogels have been investigated. The hydrogels were prepared by free-radical polymerization of the monomers acrylamide (AAm), N,N-dimethylacrylamide (DMA), and N-isopropylacrylamide (NIPA) in aqueous clay suspensions at 21 °C. Laponite with a radius of gyration in distilled water of 20 nm was used as clay particles in the hydrogel preparation. The reactions with AAm monomer were carried out in the presence of the chemical crosslinker N,N′-methylenebis(acrylamide) (BAAm). It was found that the volume of nanocomposite hydrogels immersed in water rapidly increases and attains a maximum value after about one day. Surprisingly, further increase in the swelling time results in the deswelling of the gels until they reach a limiting swelling ratio after about 5 days. This unusual swelling behavior is observable only when the clay concentration in the hydrogel is above the overlap threshold c^∗. Swelling measurements combined with the elasticity tests show that the effective crosslink density first decreases, but then increases with increasing time of swelling of the hydrogels. The results were explained in terms of the rearrangements of the highly entangled polymer chains and clay particles during the gel volume change.     

Preparation and performance of nanocomposite hydrogels based on different clay

To look for economic substitute of Laponite, two kinds of clay minerals purchased in China were chosen to prepare nanocomposite hydrogels. Structure, morphology, temperature-sensitivity and swelling behavior were investigated by XRD, SEM, DSC and gravimetric method. In comparison with hydrogel cross-linked by Laponite XLG, the hydrogel with hectorite (Lvjie trademark) or montmorillonite (G-105) as cross-linker exhibited higher swelling ratios as well as faster response rate. In the case of temperature-sensitivity, the volume phase transition temperature (VPTT) of the hydrogels cross-linked by hectorite (Lvjie trademark) and montmorillonite (G-105) was 31–33 °C, slightly different from hydrogels with Laponite XLG. The hydrogel with montmorillonite (G-105) was brown and fragile. The hectorite (Lvjie trademark) appeared as optimal substitute of Laponite in hydrogels because the prepared hydrogel exhibited high swelling ratio, rapid response rate, excellent thermal responsibility, good dispersion in hydrogel matrix and high storage modulus.     

Swelling and Metal Ion Adsorption Characteristics of Radiation Synthesized Stimuli Responsive PAAm-KC Semi – IPN Hydrogels

The preparation of super absorbent hydrogels based on Kappa-carrageenan and polyacrylamide was carried out by electron beam irradiation technique. The gels were characterized for their temperature and pH responsive behavior by equilibrium swelling experiments and for their structure by FTIR, DSC, and SEM techniques. The effect of polymer composition, dose applied, pH, and temperature on swelling was evaluated. The suitability of these systems as matrix materials for the uptake of Cu²⁺ and Ni²⁺ ions from aqueous solutions was studied. The influence of gel structure and pH conditions on metal ion uptake capacity of gels were investigated. The metal ion uptake capacity has been correlated with the swelling ability of the gels.