clay and 2-acrylamido-2-methylpropanesulfonate

Developing the application of high-strength hydrogels has gained much attention in the fields of medical, pharmacy, and pollutant removal due to their versatility and stimulus-responsive properties. In this presentation, a high-strength freestanding elastic hydrogel membrane was constructed by clay nanosheets, N, N-dimethylacrylamide and 2-acrylamide-2-methylpropanesulfonic acid for adsorption of methylene blue and heavy metal ions. The maximum values of elongation and Young's modulus for 0.5% AMPSNa hydrogel were 1901% and 949.4 kPa, respectively, much higher than those of traditional hydrogels. The adsorptions were confirmed to follow pseudo-second kinetic equation and Langmuir isotherm model fits the data well. The maximum adsorption capacity of hydrogel towards methylene blue was 434.8 mg g(-1). The hydrogel also exhibited higher separation selectivity to Pb(2+) than Cu(2+). The methylene blue adsorbed onto the hydrogel membrane can be photocatalytically degraded by Fenton agent and the hydrogel membrane could be recycled at least five times without obvious loss in mechanical properties. In conclusion, this presentation demonstrates a convenient strategy to prepare tough and elastic clay nanocomposite hydrogel, which can not only be applied as recyclable membrane for the photocatalytic degradation of organic dye, but also for the recovery of valuables.

Topics: Acrylamides; Adsorption; Alkanesulfonates; Aluminum Silicates; Clay; Hydrogel, Polyethylene Glycol Dimethacrylate; Membranes, Artificial; Methylene Blue; Microscopy, Electron; Nanocomposites; Waste Disposal, Fluid; Water Pollutants, Chemical; Water Purification

The aim of this study was to investigate the benefits of incorporation of poly(methyl methacrylate)-grafted-nanoclay on the bond strength of an experimental one-bottle dentin bonding system. The effect of the modification on the stability of the nanoparticle dispersion in the dilute adhesive was also studied.. Poly(methyl methacrylate) was grafted onto the pristine Na-MMT nanoclay (Cloisite Na(+)) through the free radical polymerization of methyl methacrylate in an aqueous media in the presence of ammonium persulfate as initiator. A reactive surfactant (AMPS) was also used in the reaction recipe to provide active sites on the surface of the nanoclay. The grafting polymerization reaction was carried out at 70 degrees C. The PMMA-g-nanoclay was then coagulated in methanol and filtered. The resulting PMMA-g-nanoclay was characterized using FTIR, TGA, X-ray diffraction (XRD) and particle size distribution analysis. The modified nanoclay was added to an experimental dentin bonding system as filler and the morphology of the nanoclay layers in the adhesive matrix was studied using TEM and XRD. Shear bond strength of the adhesives containing different filler contents was tested on the caries-free extracted human premolar teeth. The mode of failure was studied by scanning electron microscopy. The stability of the nanoclay dispersion in the dilute adhesive was also studied using a separation analyzer. The results were then statistically analyzed and compared.. The grafting of poly(methylmethacrylate) onto the nanoclay was confirmed and the results revealed a partially exfoliated structure for the PMMA-g-nanoclay. Incorporation of the modified nanoclay provided a dentin bonding system with higher shear bond strength. The dispersion stability of the modified nanoparticles in the dilute adhesive was also increased more than 40 times in comparison with the pristine nanoclay.. The grafting modification provided nanoclay particles with higher dispersion stability than pristine Na-MMT nanoclay in a dilute dentin bonding system. Incorporation of the modified nanoclay into the bonding system provided higher shear bond strength. The finding would be beneficial in producing nano-filler containing adhesive systems.

Topics: Acrylamides; Alkanesulfonates; Aluminum Silicates; Ammonium Sulfate; Bentonite; Bisphenol A-Glycidyl Methacrylate; Clay; Dentin-Bonding Agents; Electron Probe Microanalysis; Free Radicals; Hot Temperature; Humans; Materials Testing; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nanocomposites; Particle Size; Polymers; Polymethyl Methacrylate; Shear Strength; Spectroscopy, Fourier Transform Infrared; Stress, Mechanical; Surface Properties; Surface-Active Agents; Thermogravimetry; X-Ray Diffraction