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N cyclohexylacrylamide based hydrogels II: Synthesis and characterization of poly(N cyclohexylacrylamide co acrylamide/sodium acrylate) hydrogels

N cyclohexylacrylamide based hydrogels II: Synthesis and characterization of poly(N cyclohexylacrylamide co acrylamide/sodium acrylate) hydrogels

In the present study ,a series of Poly(N-cyclohexylacrylamide -co –acrylamide / Sodium acrylate) Hydrogels were synthesized by free-radical copolymerization in Water/Methanol medium using Ammonium persulfate (APS) as the initiator and N,N-methylenebisacrylamide (MBA) as a crosslinker at 60 0 C. The amount of N-cyclohexylacrylamide (NCA) and Acrylamide (AM) monomers was fixed and the amount of sodium acrylate(AcNa) was varied. The Hydrogels were characterized by IR spectroscopy. The swelling behavior of Hydrogels showed that the degree of swelling was increased with increasing the amount of Ac Na. The surface morphology indicated porous and well type structure.
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Lee mas

SYNTHESIS, CHARACTERIZATION, SWELLING BEHAVIOR AND DIFFUSION STUDIES OF POLY(N CYCLOHEXYLACRYLAMIDECO  ACRYLAMIDE 2 ACRYLAMIDO 2 METHYLPROPANE SODIUM SULPHONATE) SILVER NANOCOMPOSITE HYDROGELS

SYNTHESIS, CHARACTERIZATION, SWELLING BEHAVIOR AND DIFFUSION STUDIES OF POLY(N CYCLOHEXYLACRYLAMIDECO ACRYLAMIDE 2 ACRYLAMIDO 2 METHYLPROPANE SODIUM SULPHONATE) SILVER NANOCOMPOSITE HYDROGELS

In the present study Poly(N-cyclohexylacrylamide-co-acrylamide-2- acrylamido-2-methyl-1- propane sodium sulfonate) Ag nanocomposite hydrogels was synthesized by in situ free-radical copolymerization in water/methanol medium using ammonium persulfate as the initiator, tetramethylethylenediamine as accelerator and N,N’- methylenediaminde as cross-linker at 60ºC. Analysis and characterization of the silver nanocomposite hydrogel was performed through monitoring its swelling behavior, diffusion studies, FTIR spectroscopy, SEM/EDX and XRD studies. Effects of monomer ratio on the swelling properties of the samples were investigated. Samples were used to remove organic dye (methylene blue) and heavy metal ion (Cd 2+ ) from aqueous solution and it was found that increase in monomer concentration into the hydrogel network increased the adsorption capacity of the silver nanocomposite hydrogel.
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I.  THE BINDING OF Cu(II) and Zn(II) TO POLY-N-ISOPROPYLACRYLAMIDE AND ITS EFFECTS ON THE PHASE TRANSITION  and  II.  THE SYNTHESIS AND CHARACTERIZATION OF NICKELALACTONES CHELATED BY P-N-P PINCER LIGANDS, Luke Aaron Fulton

I. THE BINDING OF Cu(II) and Zn(II) TO POLY-N-ISOPROPYLACRYLAMIDE AND ITS EFFECTS ON THE PHASE TRANSITION and II. THE SYNTHESIS AND CHARACTERIZATION OF NICKELALACTONES CHELATED BY P-N-P PINCER LIGANDS, Luke Aaron Fulton

The previous sections have prepared raw data and set up the regressions needed to interpret it, while the rest of this chapter shall explain how to perform the interpretation. Ultimately the question is “which linear function most appropriately transforms a given intensity measurement into an average particle size value?”. Unfortunately, although Intensity is a function of time, I(t), average particle size cannot be considered a function of intensity, S(I(t)). This is intuitively apparent when displayed graphically; each intensity value could reasonably have two different size outputs. Therefore, selection criteria are used to achieve the correct assignment based contextually by the surrounding data points as well as a fundamental assumption; particle sizes are strictly increasing, not decreasing. The model as it is described here should never be used when this assumption cannot be reasonably accepted.
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Synthesis and Characterization of Temperature Sensitive and Chemically Cross Linked Poly( N isopropylacrylamide)/Photosensitizer Hydrogels for Applications in Photodynamic Therapy

Synthesis and Characterization of Temperature Sensitive and Chemically Cross Linked Poly( N isopropylacrylamide)/Photosensitizer Hydrogels for Applications in Photodynamic Therapy

Photodynamic therapy (PDT) relies on the activation of a photosensitizer (PS) using visible or near IR light to generate reactive oxygen species, such as singlet oxygen, as cytotoxic agents. 1,2 Porphyrins feature prominently among the clinically approved PDT drugs and typical examples of porphyrin-based drugs include Photofrin® (porfimer sodium), Visudyne® (verteporfin), and Foscan® (temoporfin). 2,3 A recurring problem is the intrinsically low water-solubility of many porphyrinoid PSs and their tendency to aggregate in polar solvents and biological media. Aggregation results in quenching of the excited states, thus lowering the singlet oxygen yields, and impacts the ability of a PS to reach the target tissue limiting its clinical use. In order to overcome these limitations and to obviate side effects different strategies to improve the pharmacological profile of PSs have been developed. 4 In terms of approved drugs this mostly involves liposomal formulations (Visudyne®), polar functionalities in the PS (Photofrin®), or the use of biosynthetic precursors (Levulan®). This is complemented by a range of nanomedicinal strategies, incorporation of water-soluble side chains, or other formulation techniques for second and third generation PSs. 5,6
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Interpenetrated Chitosan Poly(Acrylic Acid Co Acrylamide) Hydrogels  Synthesis, Characterization and Sustained Protein Release Studies

Interpenetrated Chitosan Poly(Acrylic Acid Co Acrylamide) Hydrogels Synthesis, Characterization and Sustained Protein Release Studies

A great variety of systems have been prepared by graft- ing synthetic polymers onto polysaccharides. Of particu- lar interest are those based on the graft polymerization of monomers such as acryl amide [18], acrylic acid [19], N-isopropylacrylamide [20] and N-vinylpyrrolidone [21] onto chitosan. Chitosan, (1,4)-[2-amino-2-deoxy-β-D- glucan] is a deacetylated derivate of chitin, a natural oc- curring polymer. It is widely studied in pharmaceutical and biomedical fields because of its biodegradability, biocompatibility, non toxicity and interesting structural properties [22]. The functional amino and hydroxyl groups in chitosan allow the preparation of chitosan de- rivatives with improved properties under relatively mild conditions [23]. Mahdavinia et al. synthesized poly (ac- rylic acid-co-acrylamide) grafted chitosan, and studied the effect of the buffer solution, ionic strength and cro- ss-linker concentration on the swelling properties of these systems. They observed that water uptake increased with increasing the acrylic acid concentration in the mo- nomer feed. However after hydrolysis with 1 N NaOH at 100˚C for 60 min the samples with high acrylamide ratio exhibited increased swelling [24]. However, in this study no use was made of microstructural techniques (EDX, SEM) for characterizing the hydrogels prepared and there was no report on their mechanical properties, biocom- patibility and their potential as matrices for drug or pro- tein release.
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Synthesis and Rheological Characterisation of the Natural gum Polysaccharide and Acrylic acid based hydrogels

Synthesis and Rheological Characterisation of the Natural gum Polysaccharide and Acrylic acid based hydrogels

Gum ghatti and poly (acrylic acid) based hydrogels prepared by free radical polymerization reaction initiated by initiator of potassium per sulphate (KPS) and N, N, MBA used as crosslinker. In this work, we prepared hydrogels by using Gum ghatti as natural gum polysaccharide with a variation of concentration of crosslinker. In rheology characterization, hydrogels systems exhibit the shear thinning flow behavior. Frequency sweep carried out in the linear viscoelastic regime (LVR). Frequency sweep results revealed that the storage modulus increased with angular frequency as compared to loss modulus. Furthermore, the temperature sweep performed at 15 0 C to 95 0 C. It can be observed that
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Thermo  and pH Responsive Hydrogels Based on N Isopropylacrylamide and Allylamine Copolymers

Thermo and pH Responsive Hydrogels Based on N Isopropylacrylamide and Allylamine Copolymers

This corresponds to the evaporation of weakly associ- ated water. The quantity of the weakly associated water depends on the composition of hydrogels. NIPA hy- drogel without ionic monomer is characterized by the weight loss of about 64%. On incorporating 10 wt% and 40 wt% of AlAmH into hydrogel structure (hydrogel composition P(NIPA-co-AlAm) 9:1 and 2:3, respectively), quantity of the weakly associated water sharply increases up to 78% and 85%, respectively due to the incorporation of highly hydrophilic domains containing amino-groups. Further increase of AlAmH content up to 60% (hydrogel P(NIPA-co-AlAm) 2:3) results in decreasing content of weakly associated water to about 68%. Despite the con- siderable rise of weakly associated water quantity in the hydrogels, copolymers containing allylamine are charac- terized by much better elastic and mechanical properties as compared to NIPA homopolymers.
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Formulation in-vitro evaluation of herbal hydrogel by using “ricinus communis” leaf extract

Formulation in-vitro evaluation of herbal hydrogel by using “ricinus communis” leaf extract

Liquid- Liquid suspension polymerization: The porous Hydrogels are prepared by suspension polymerization method in liquid-liquid systems. In this method the monomers which are immiscible are first dissolved along with active ingredients in a suitable solvent monomer and are then dispersed in the aqueous phases which consist of like surfactant, suspending agent to facilitate formation of suspension. The polymerization is then activated by increasing temperature or irradiation or by addition of catalyst. The polymerization process continues the formation of a reservoir type of system with spherical structure. After the polymerization process the solvent is removed leaving the spherical structured porous microspheres i.e., Hydrogels.
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Hydrogels from Chitosan and a Novel Copolymer Poly(N Vinyl 2 Pyrrolidone Co Acrolein)

Hydrogels from Chitosan and a Novel Copolymer Poly(N Vinyl 2 Pyrrolidone Co Acrolein)

PVP, a synthetic polymer and chitosan, a natural polymer are biocompatible and have presented a great variety of in- teresting properties for cosmetic, biomedical, pharmaceutical and biotechnological applications, Many alternatives to improve the polymer propeties has been made as bleeding polymers, for example. In this work, two different techniques of hydrogel attainment were used: one from mixtures of acid aqueous co-solutions of chitosan and PVP, whose resul- tant films and solutions were irradiated, afterwards, by ultraviolet radiation (λ = 254 nm), another one from the reac- tion of poly (N-vinyl-2-pyrrolidone-co-acrolein)-a novel copolymer synthesized in our biomaterials laboratory-and chitosan. In the first one alternatives it was possible produce hydrogels directly from mixtures of aqueous acidic co-solutions of both polymers. In the second one, the attainment of hydrogels from Schiff base has proved to be an ef- fective methodology for the production of hydrogels, showing good values of gel content and swelling.
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Preparation and Characterization of Macroporous Hydrogels from Copolymers Networks

Preparation and Characterization of Macroporous Hydrogels from Copolymers Networks

New hydrogels based on (MAA) and (NVP) copolymers crosslinked with (BAA), were prepared by free radical cross-linking copolymerization, with a NVP percent molar composition of 10, 47.5 and 85. These hydrogels have been characterized by (FTIR), (SEM), (TGA /DSC) coupling. The results show four steps of degradation. The degradation rate is inversely proportional to the mole percent of NVP, and SEM shows that the hydrogels have a pore size between 7.14 to 13.33 μm.

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Thermoresponsive, stretchable, biodegradable and biocompatible poly(glycerol sebacate)-based polyurethane hydrogels

Thermoresponsive, stretchable, biodegradable and biocompatible poly(glycerol sebacate)-based polyurethane hydrogels

Metabolic activity assay with resazurin was used to evaluate the in vitro cell viability and proliferation of ADSCs (Figure 7A-C) and FIBs (Figure S8) on PEU hydrogels for up to 9 days, while confocal fluorescence microscopy was performed for cell morphology analysis (Figure 7A-C and S8). The PEU hydrogels showed no evidence of toxicity to either ADSCs or FIBs. Two-way ANOVA found significant difference between the metabolic activities of ADSCs (p < 0.0001) and FIBs (p < 0.05) in respect to the test time, while no difference in metabolic activities was found between the different PEU hydrogels. Two-sample t-test (p < 0.05) found PEU-1000 and PEU-1450 hydrogels presented a significant increase in metabolic activity for both cell types from day 0 to day 6 or 9, while both cell types showed statistically insignificant metabolic activities on the PEU-400 hydrogels. Maximum metabolic activity was achieved for both seeded cell types at day 6 without significant differences between day 6 and 9. ADSCs exhibited the highest metabolic activity on PEU-1000 hydrogels at day 6 (73% increase compared to day 0 cell-seeded specimens), while FIBs demonstrated the highest metabolic activity on PEU-1450 hydrogels at day 6 (51% increase compared to day 0 cell-seeded specimens). The colorimetric measurements were visually confirmed by the color change of the blue resazurin dye, with a clear change to a purple color (resorufin) for both cell types on all PEU hydrogels from day 0 to day 9 (Figure S9). The reduction of blue resazurin to purple resorufin was only seen when living cells were present (cell-free control specimens always remained blue). In contrast, the cell- seeded area on PEU-400 and PEU-1000 hydrogels turned in a distinct pink color, confirming the presence of cells on the surfaces and indicating similar metabolic activities between days 6 and 9 (Figure 7A-C and Figure S8). In contrast, the surfaces of the cell-seeded PEU-1450 hydrogels
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Diffusion of dextran within poly(methacrylic acid) hydrogels

Diffusion of dextran within poly(methacrylic acid) hydrogels

We describe a fluorescence correlation spectroscopy investigation into the diffusion of fluorescein- tagged dextran (FDEX) in a poly(methacrylic acid) (PMAA) hydrogel. The temperature dependence of FDEX diffusion is shown to follow Zimm behaviour in pure water, and the decrease in the diffusion coefficient when in the PMAA hydrogel has been modelled. The addition of acid and alkali (HCl and NaOH respectively) not only control the swelling and collapse of the hydrogel but also reveal a strong pH dependence of the dextran diffusion coefficient, which shows a (non-monatonic) increase with pH. The addition of NaCl and CaCl 2 salts similarly showed evidence of network swelling, most notably at low salt
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Numerical Analysis of Temperature-Sensitive Hydrogels for Controlled Drug Release

Numerical Analysis of Temperature-Sensitive Hydrogels for Controlled Drug Release

in drug delivery systems. To design an effective hydrogel applicable network, mathematical modeling has a critical role. A successful drug delivery device relies not only on intelligent network design but also on accurate prior mathematical modeling of drug release profiles. In this study, the modeling of the inflation behavior of temperature-sensitive hydrogel has been done by providing a mathematical model according to the thermodynamics and kinetics of the temperature-sensitive gel and also considering the heat transfer into the hydrogels during the inflation. The proposed model has been investigated numerically. The comparison between numerical and experimental results shows perfectly success in integrating equations of inflation thermodynamics and kinetics for modeling the inflation behavior of temperature-sensitive hydrogels that provide a new step in the modeling of such systems .
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RECENT ADVANCES IN THE SYNTHESIS AND APPLICATIONS OF COLLAGEN BASED HYDROGELS: A REVIEW

RECENT ADVANCES IN THE SYNTHESIS AND APPLICATIONS OF COLLAGEN BASED HYDROGELS: A REVIEW

Specifically, the hydrogels formed from the partial digestion, solubilization and in situ polymerization of decellularized tissues can retain the biological activity of the native ECM. Therefore, these hydrogels have complex biochemical compositions, fibrous protein content (e.g., collagen, fibrin, elastin), proteoglycans (PGs), and glycosaminoglycans (GAGs) that closely mimic the native 3D tissue environment, compared to simple composition hydrogels [12]. The remaining ECM molecules after extracting the coll agen have a direct relationship with the in situ polymerization process, structure and properties of the generated hydrogels. A higher content of matrix proteins improves the mechanical properties and proteolytic degradation rate, exhibiting enhanced biocompatibility properties [13]. The main ECMs used to extract collagen and to generate hydrogels are: rat tail tendon [14], bovine Achilles tendon [15], bovine pericardium [13], porcine intestinal submucosa [16], porcine bladder [17], fish skin [18], and porc ine skin [19]. These collagen based hydrogels have shown bioactivity and biocompatibility associated with their residual composition. Recently, a review has been reported about diverse ECMs employed in the design of biomedical hydrogels, describing the main role of collagen based hydrogel with characteristic composition on the improved applicability [20]. Generally, the collagen hydrogels have been studied as substrates for ophthalmology, sponges for burns/wounds, systems for controlled delivery of functio nal molecules or nanoparticles, and matrices for 3D cell culture. They are also investigated for tissue engineering including skin replacement, bone substitutes, and artificial blood vessels and heart valves [21].
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Hemicellulose Based Hydrogels Present Status and Application Prospects: A Brief Review

Hemicellulose Based Hydrogels Present Status and Application Prospects: A Brief Review

IPNs are ‘‘alloys’’ of cross-linked polymers, at least one of them being synthe- sized and/or cross-linked within the immediate presence of the other, without any covalent bonds between them, which cannot be separated unless chemical bonds are broken (Dragan, 2014; Myung et al., 2008). IPN is a multi-component network made by molecular scale penetration of a linear or branched polymer into a cross-linked network that offer superior control and versatility over single network hydrogels with possibilities to tailor-make products with desired prop- erties by mixing countless combinations of polymers with complementing cha- racteristics (Matricardi et al., 2013; Myung et al., 2008; Reddy, Rao, Vani, Rao, & Lee, 2016). In study by Malaki et al. employed the abundant hemicellulose by green method to fabricate the semi-IPN hydrogels. The hydrogel was directly produced by a facile and green synthetic pathway through cross-linking mod- ified. A category of said composite networks can be developed by the simulta- neous or sequential cross-linking of at least two polymer networks in juxtaposi- tion. In another study of Maleki and coworkers (Maleki et al., 2017), AcGGM was employed to prepare IPNs-hydrogels via free radical polymerization and “click chemistry reaction” (Figure 5). As-prepared IPNs hydrogels indicated faster swelling rates, highly porous structure and significantly improved shear storage modulus than the corresponding precursor single networks of AcGGM (Maleki et al., 2017).
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A Review on Hydrogels

A Review on Hydrogels

These unique physical properties of hydrogels have stimulated particular interest in their use in drug delivery applications. Their highly porous structure can easily be tuned by controlling the density of cross-links in the gel matrix and the affinity of the hydrogels for the aqueous environment in which they are swollen. Their porosity also permits loading of drugs into the gel matrix and subsequent drug release at a rate dependent on the diffusion coefficient of a small molecule or a macromolecule through the gel network 6 .Since the polymer cannot dissolve due to the covalent crosslinks, water uptakes far in excess of those achievable with hydrophilic linear polymers can be obtained 9 .
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POLY(VINYL ALCOHOL) NANOCOMPOSITE HYDROGELS FOR INTERVERTEBRAL DISC PROSTHESES

POLY(VINYL ALCOHOL) NANOCOMPOSITE HYDROGELS FOR INTERVERTEBRAL DISC PROSTHESES

Human IVDs have been found to increase in strain by 20–108% after 30 minutes of creep [23, 64]. Strain did not reach equilibrium deformation after 30 minutes under the estimated body weight at the lumbar disc level [64] or 15 hours at 177.92 N [63]. Creep in the PVA and PVA-NC hydrogels in this study was low compared to human IVDs. Unfilled PVA increased in strain by 10–25% after 1 hour, and by 30–40% with nanofiller addition (Figure 4.20). However, we used a low creep stress in this study, equal to approximately 25–33% of the stress used in the IVD tests, since the hydrogels were more compliant than the natural IVD, and the initial strains in the IVDs were ap- proximately half of those in the 10% PVA and PVA-NC hydrogels. Although creep in IVDs is an important mechanism for energy dissipation following loading, a low degree of creep in the hydrogels would be desirable from the viewpoint of engineering design. The decrease in IVD height due to fluid is recovered each day during rest [42]. In poly- meric systems however, viscous flow of amorphous regions could lead to unrecoverable deformations that would have implications for the performance of the device in vivo, since the disc space could decrease in height and would eventually require intervention. Viscous movement of PVA molecules in PVA and PVA-NC hydrogels may cause per- manent deformation to occur. However, the hydrophilicity of the PVA-NC hydrogels may also encourage swelling and fluid flow back into the structure upon removal of load to aid in restoring height during rest. Future investigations of viscoelastic properties should include testing of the hydrogels between porous platens since endplate permeabil- ity also has an impact on both creep and creep recovery of IVDs [235]. Porous platens would allow for unimpeded fluid flow back into the hydrogels for determining the rate of creep recovery. Furthermore, unconfined compression testing between porous platens may have implications on stress-strain curves, and decrease modulus and strain rate de- pendence.
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Synthesis of carboxymethylcellulose/starch superabsorbent hydrogels by gamma-irradiation

Synthesis of carboxymethylcellulose/starch superabsorbent hydrogels by gamma-irradiation

and relatively high (~55%) gel fraction, significantly higher than observed for pure CMC hydrogels. Moreover, the swelling properties of these gels were higher than those of the carboxymethylcellulose-based superabsorbents with the same gel fraction prepared with crosslinking agent [18] or introducing low concentrations of acrylic acid [46]. On the other hand, CMC/starch systems needed higher solute concentration and dose to achieve the same gela- tion and showed inferior swelling properties at lower gel fractions. The use of starch allows avoiding the use of toxic monomers and crosslinkers, which may be a signifi- cant advantage depending on the application.
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Formulation and Characterization of pH based Stimuli Sensitive based Hydrogels for the Treatment of Ocular Infection

Formulation and Characterization of pH based Stimuli Sensitive based Hydrogels for the Treatment of Ocular Infection

The goat cornea was purchased from slaughter house and washed with water for several minutes. They were soaked in the STF fluid for few minutes. The goat cornea was preferred as the membrane for the Franz diffusion cell. Goat corneas were kept in between donor and receptor compartment. The formulations F5 was taken for the ex-vivo studies based on the release study showed maximum % cumulative drug release and it was taken in donor compartment. The studies were carried out for the period of 8 hours by withdrawing the sample and replacing 3 ml of STF fluid from the receptor compartment. Then the sample was by UV visible spectrophotometer at 294 nm and the graph was plotted with % cumulative drug release vs. time.
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Gamma Irradiation as an Environment Friendly Process for Synthesis of Hydrogels

Gamma Irradiation as an Environment Friendly Process for Synthesis of Hydrogels

ABSTRACT: Hydrogels have gained considerable importance during the last five decades as an industrially useful material. Due to their unique property of water absorption, they find potential applications in soil conditioning by maintain water level of soil, diapers for infants and adults, feminine hygiene products, wound dressings, etc. While synthetic hydrogels are based on water and synthetic monomer (acrylic acid), semi-synthetic hydrogels are based on water synthetic monomer (acrylic acid) and a natural material (gum arabic). In the present study, synthetic (based on acrylic acid) as well as semi-synthetic (based on gum Arabic and acrylic acid) hydrogels have been synthesized using gamma irradiation technique. A comparative study on the gel content and water absorption behaviour of synthetic and semi-synthetic hydrogels has been carried out in the present paper. Through this study, it has been demonstrated that gamma irradiation is an effective tool for the synthesis of hydrogels. The study reveals that stable and cross-linked hydrogels have been obtained after subjecting to - irradiation. Water absorption of semi-synthetic hydrogels was found to be higher than that of synthetic hydrogels.
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