Preparation and Characterization of Organic-Inorganic Composite Materials Based on Poly(acrylamide) Hydrogels and Clay Minerals

Organic-inorganic hybrid composite materials consisting of poly(acrylamide) hydrogel (PAAH) and clay minerals such as bentonite, montmorillonite, and kaolin as well as silica and titanium dioxides were obtained by in situ synthetic protocol and characterized by swelling measurements, FTIR, SEM, XRD and DSC. Concentration of clay minerals embedded within PAAH is varied from 2.5 to 30wt.%. The swelling degree of composite hydrogels K-s and the constants k and n that characterize the mode of the penetrant (e.g. water) transport mechanism were determined. It was found that the swelling degree of PAAH/Clay minerals is in the range of 7-15g/g and changes in the following order: PAAH/Bentonite>PAAH/TiO2>PAAH/SiO2>PAAH/Kaolin approximate to PAAH/Montmorillonite. The influence of pH, temperature, ionic strength, water-organic solvent mixture, as well as the content of clay minerals and crosslinking agent on swelling-deswelling behaviour of composite hydrogel materials was evaluated. For some PAAH/Clay minerals system the enthalpy of mixing H-m was calculated. The positive values of the H-m indicate that the swelling of composite hydrogel materials in water has the endothermic character. It was demonstrated that PAAH-clay mineral composites can potentially be used as pigs for the cleaning of the internal surface of main pipes from debris, sand and asphaltene-resin-wax deposits.