Swelling behaviors of vermiculite/poly (acrylic acid) superabsorbent composite induced by glow discharge electrolysis plasma

A vermiculite/poly(acrylic acid) (VMT/PAA) superabsorbent composite is prepared in aqueous solution by a simple one-step using glow-discharge electrolysis plasma (GDEP) induced graft copolymerization of acrylic acid (AA) and vermiculite(VMT), in which N,N'-methylenebisacrylamide (MBA) is used as a crosslinker. The structure of the resulting product is characterized by FTIR and XRD. A mechanism for synthesis of vermiculite/poly(acrylic acid) superabsorbent composite is proposed and the swelling kinetics in distilled water is systematically investigated. The influences of various pH values and salts solutions on the equilibrium swelling ratio are preliminarily studied. The results show that the swelling kinetics follows the pseudo-second-order swelling kinetics model. The vermiculite/poly(acrylic acid) superabsorbent composite is responsive to pH and salts, and it has excellent on-off switching behavior as reversible swelling and deswelling. In addition, the equilibrium swelling ratio of univalent cation salt solution is higher than that of bivalent cation salt solution.