Super water absorbency OMMT/PAA hydrogel materials with excellent mechanical properties

Abstract

Superabsorbent hydrogels with excellent mechanical properties are fabricated by introducing organic montmorillonite (OMMT) into poly(acrylic acid) (PAA) hydrogels via simple UV irradiation polymerization. The obtained OMMT/PAA composite hydrogels are composed of a three-dimensional macroporous network structure. The effects of deionized water and OMMT content on the UV-induced polymerization progress were systematically investigated. OMMT/PAA composite hydrogels with superior water absorbency and excellent mechanical properties can be obtained when the initial amount of deionized water is 95.7% (the ratio is H₂O/(H₂O + AA) in weight) and the content of OMMT is 10% (the ratio is OMMT/(OMMT + AA) in weight). The maximum water absorbency in deionized water is 2786 g g⁻¹ due to the highly reactive hydroxy groups in OMMT, which is more than 5 times higher than that of PAA hydrogels (545 g g⁻¹). The OMMT/PAA containing 10% OMMT has excellent elasticity and can be stretched up to 2200% for a fresh-prepared hydrogel. It can also sustain a load weight of 650 g, and has excellent recoverability. The compressive stress–strain measurements also verify that the OMMT/PAA hydrogel containing 10% OMMT has obviously improved mechanical properties compared to the others. The combination of high water absorbency, excellent elasticity mechanical properties, efficient recoverability and facile preparation provides a new way for fabricating high-performance hydrogel materials.