clay and acrylic-acid

In this work, nanocomposite hydrogels were prepared by gamma-radiation copolymerization of acrylic acid (AAc) onto plasticized starch (PLST)/montmorillonite clay (MMT)/chitosan (CS) blends. The effect of irradiation dose and MMT nanoparticle contents on the gel fraction and water absorption characters of PAAc-co-(PLST/MMT/CS) hydrogels was investigated. In addition, the structure-property behavior of the nanocomposite hydrogels was characterized by FTIR spectroscopy, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The study showed that the appropriate dose of gamma irradiation to achieve homogeneous nanocomposite hydrogels films and the highest absorption in water was 15 kGy, regardless of composition. The introduction of MMT up to 5-wt (%) improved the physical properties and enhanced the drug uptake-release characters. The effect of the nanocomposite hydrogels on skin wound healing were evaluated by rat models, taking sulfanilamide as a model drug. The profiles of rat skin after different time intervals up 21 days revealed that wounds treated with the copolymer hydrogels were healed faster which it may considered as a potential candidate for wound dressing materials.

Topics: Acrylates; Animals; Bandages; Chemical Phenomena; Chitosan; Clay; Drug Carriers; Gamma Rays; Hydrogels; Nanocomposites; Nanoparticles; Plasticizers; Polymers; Rats; Spectrum Analysis; Starch; Thermogravimetry; Wound Healing

In this work, novel sodium alginate-based double-network hydrogel beads were prepared and applied for the water-retention and slow release of fertilizers (WSF). The WSF beads were prepared by ion-crosslinking and the free radical polymerization of acrylic acid, acrylamide, and polymerizable β-cyclodextrin in the presence of urea-loaded halloysites. The WSF beads were characterized using SEM, FTIR, and TGA. Their swelling capacity and water retention were measured by a weighing method and their slow-release behavior was studied by spectrophotometry. The water retention and slow release results showed that the fertilizer displayed improved urea release and water retention properties, indicating that halloysite nanotubes clearly improved the performance of fertilizers. In addition, the experimental data of the slow release of urea in water and soil better fitted the Korsmeyer-Peppas model compared with the Higuchi model, a zero-order model or a first order mode. The release behavior of the fertilizer beads followed a Fickian diffusion mechanism.

Topics: Acrylamide; Acrylates; Alginates; beta-Cyclodextrins; Clay; Fertilizers; Hydrogels; Hydrogen-Ion Concentration; Nanotubes; Polymerization; Spectroscopy, Fourier Transform Infrared; Water

Allyl isothiocyanate (AITC) is a highly volatile organic compound that is a potential antibacterial agent against food spoilage bacteria. Naturally formed halloysite nanotubes (HNTs) have a length of 1 μm and diameter ranging from 10 to 50 nm. The biocompatibility of HNT allows safe release of drugs to bacterial cells at a relatively low concentration compared to other systems. We encapsulated AITC inside HNTs that were then coated with sodium polyacrylate (PA). The HNT-AITC-PA nanocomposites (NCs) were characterized by Fourier-transform infrared spectroscopy, thermal gravimetric, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses. In vitro antibacterial activity was evaluated against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria capable of food spoilage. HNT-AITC-PA NCs effectively inhibited the growth of both bacteria. The activity was pronounced against E. coli at 100 μg/mL, with concentrations of 25 μg/mL and 200 μg/mL reducing the viable cell population by 41% and 96%, respectively. Thus, HNT-AITC-PA NCs are a novel and promising material against food spoilage bacteria for use in active antibacterial food packaging.

Topics: Acrylates; Anti-Bacterial Agents; Clay; Dynamic Light Scattering; Escherichia coli; Food Preservation; Isothiocyanates; Microbial Sensitivity Tests; Nanocomposites; Nanotubes; Particle Size; Spectroscopy, Fourier Transform Infrared

Chitosan/carboxy methyl chitosan (CMC) grafted sodium acrylate-co-acrylamide/nanoclay superabsorbent nanocomposites have been synthesized in this study by following conventional and microwave assisted grafting methods. Microwave assisted grafting method showed higher grafting yield with enhanced reaction rate. Effect of nanoclay on water adsorption and swelling behaviour of both the composites in acidic, neutral and alkaline medium has been studied. Results showed enhanced swelling rate and water adsorption of both composites after adding 5% of silane treated nanoclay. Dye adsorption capacity of both the composites has been investigated for crystal violet, napthol green and sunset yellow dyes. It was observed that addition of 5% nanoclay enhanced the dye adsorption in both the composites. Langmuir and Freundlich isotherm models have been used to explain the dye adsorption capabilities. The chitosan and CMC nanocomposites follow both the models with R

Topics: Acrylamide; Acrylates; Adsorption; Aluminum Silicates; Chemistry Techniques, Synthetic; Chitosan; Clay; Coloring Agents; Hydrogen-Ion Concentration; Kinetics; Nanocomposites; Temperature; Water; Water Pollutants, Chemical

The research on a self-decontaminating surface has received significant attention because of the growth of pathogenic microorganisms on surfaces. In this study, a novel and simple technique for producing an active surface with antimicrobial functionality is demonstrated. A tethering platform was developed by grafting the biocide ampicillin (Amp) to a nanoclay and dispersing the nanoclay in a UV-curable acrylate coating applied on polypropylene films as the substrate. A coupling agent, [3-(glycidyloxy)propyl]trimethoxysilane, was used as a linker between the nanoclay and Amp. The Amp-functionalized clay was further modified with an organic surfactant to improve the compatibility with the coating. Several characterization assays, such as Fourier infrared transform analysis, thermogravimetric analysis, and X-ray diffraction, were conducted to confirm the presence of Amp in the nanoclay. Transmission electron microscopy images revealed that the clay particles were well dispersed in the coating and had a partial exfoliated morphology. The active coating surface was effective in inhibiting the growth of Gram-positive Listeria monocytogenes and Gram-negative Salmonella Typhimurium via contact. These findings suggest the potential for the development of active surfaces with the implementation of nanotechnology to achieve diverse functionalities.

Topics: Acrylates; Agar; Aluminum Silicates; Ampicillin; Bacterial Adhesion; Clay; Diffusion; Listeria monocytogenes; Materials Testing; Microscopy, Electron, Transmission; Nanoparticles; Nanotechnology; Polymers; Polypropylenes; Salmonella typhimurium; Silanes; Spectroscopy, Fourier Transform Infrared; Surface Properties; Surface-Active Agents; Thermogravimetry; Ultraviolet Rays; X-Ray Diffraction

In this study, superabsorbent nanocomposites of guar gum grafted sodium acrylate have been synthesized via both microwave and conventional techniques. The reaction parameters of both techniques were optimized and the microwave assisted method was proved to have higher grafting yield with lesser time of reaction as compared to the conventional method. X-ray diffraction and scanning electron microscopy analyses revealed that cloisite was exfoliated and uniformly dispersed in guar gum grafted sodium acrylate matrix. The results show that introducing cloisite into the guar gum grafted sodium acrylate network improved the swelling capability and the swelling rate of the superabsorbent nanocomposite was found to be enhanced at an optimal loading of 10% cloisite. The nanocomposites showed high water absorbency within a wide pH range. Preliminary studies on crystal violet dye removal showed promising results.

Topics: Acrylates; Adsorption; Aluminum Silicates; Chemistry Techniques, Synthetic; Clay; Galactans; Gentian Violet; Kinetics; Mannans; Microwaves; Nanocomposites; Plant Gums; Temperature; Water

In this paper, intercalation of nanoclay in the miscible polymer blend of poly(vinylidene fluoride) (PVDF) and acrylic rubber(ACM) was studied. X-ray diffraction was used to investigate the formation of nanoscale polymer blend/clay hybrid. Infrared spectroscopy and X-ray analysis revealed the coexistence of β and γ crystalline forms in PVDF/Clay nanocomposite while α crystalline form was found to be dominant in PVDF/ACM/Clay miscible hybrids. Flory-Huggins interaction parameter (B) was used to further explain the miscibility phenomenon observed. The B parameter was determined by combining the melting point depression and the binary interaction model. The estimated B values for the ternary PVDF/ACM/Clay and PVDF/ACM pairs were all negative, showing both proper intercalation of the polymer melt into the nanoclay galleries and the good miscibility of PVDF and ACM blend. The B value for the PVDF/ACM blend was almost the same as that measured for the PVDF/ACM/Clay hybrid, suggesting that PVDF chains in nanocomposite hybrids interact with ACM chains and that nanoclay in hybrid systems is wrapped by ACM molecules.

Topics: Acrylates; Aluminum Silicates; Clay; Crystallization; Nanocomposites; Phase Transition; Polyvinyls; Rubber; Scattering, Radiation; Spectroscopy, Fourier Transform Infrared; Transition Temperature; X-Ray Diffraction

A novel superabsorbent composite was synthesized by copolymerization reaction of partially neutralized acrylic acid (AA) on bentonite micropowder using N,N'-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator in aqueous solution. The superabsorbent composite (SAC) was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The water retention test of SAC was also performed. The water absorbency of SAC synthesized was found to be 352 and 110 g H(2)Og(-1) in distilled water and 0.2% NaCl, respectively. Sorption capacity of SAC was investigated for heavy metal ions (HMI) using Langmuir and Freundlich model of adsorption. The maximum adsorption capacity (Q(m)) of HMI onto the bentonite-based SAC from their solution was 1666.67, 270.27, 416.67 and 222.22 mg g(-1) for Pb(II), Ni(II), Cd(II) and Cu(II), respectively. All results suggested that SAC offers excellent potential for HMI removal from contaminated water.

Topics: Acrylamides; Acrylates; Adsorption; Aluminum Silicates; Bentonite; Cadmium; Clay; Copper; Lead; Microscopy, Electron, Scanning; Nickel; Powders; Sodium Chloride; Spectroscopy, Fourier Transform Infrared; Thermogravimetry; Water Pollutants, Chemical; Water Purification

Starch and attapulgite were utilized as raw material for synthesizing starch-graft-poly(acrylic acid)/attapulgite superabsorbent composite by graft copolymerization reaction of starch and acrylic acid (AA) in the presence of attapulgite micropowder in aqueous solution. Major factors affecting on water absorbency such as weight ratio of AA to starch, initial monomer concentration, neutralization degree of AA, amount of crosslinker, initiator and attapulgite were investigated. The superabsorbent composite synthesized under optimal synthesis conditions with an attapulgite content of 10 wt% exhibit absorption of 1077 g H(2)O/g sample and 61 g H(2)O/g sample in distilled water and in 0.9 wt% NaCl solution, respectively. This superabsorbent composite with excellent water absorbency and water retention under load, being biodegradable in nature, economical and environment-friendly, could be especially useful in agricultural and horticultural applications.

Topics: Absorption; Acrylates; Aluminum Silicates; Clay; Magnesium Compounds; Polymers; Silicon Compounds; Sodium Chloride; Starch; Waste Disposal, Fluid; Water