Swelling behavior and structural characteristics of polyvinyl alcohol/montmorillonite nanocomposite hydrogels

Abstract

A series of nanocomposite hydrogels based on polyvinyl alcohol containing 0-10 wt % of the organically modified montmorillonite clay were prepared by freezing-thawing cyclic method. The morphology of the nanocomposite hydrogels was observed by the scanning electron microscopy technique. The structural properties were determined by measuring the network mesh size, crosslinking density, and average molecular weight of polymer chains between crosslinks. The swelling behavior and the effect of swelling medium temperature on the swelling kinetics and characteristics of the nanocomposite hydrogels were also investigated. The results showed that two structural characteristics i.e., network mesh size and average molecular weight of polymer chains between crosslinks have inverse dependence on the clay loading level in the nanocomposite hydrogel, while crosslinking density shows completely direct dependence. Swelling measurements demonstrated a linear relation between the degree of swelling and the square root of immersion time at all swelling medium temperatures. The results indicated that the swelling characteristics of the nanocomposite hydrogels including the equilibrium degree of weight and volume swelling and the equilibrium water content were decreased by increasing the quantity of the clay incorporated into the hydrogel as well as by decreasing the temperature of swelling medium. While, the time required to reach to the equilibrium condition, as another swelling characteristic of the hydrogels, exhibited a completely opposite behavior.

Antibiotic eluting clay mineral (Laponite®) for wound healing application: an in vitro study

“…The study showed that the prepared material was pH sensitive due to the presence of bentonite. In contrast to our study, Sirousazar et al [35] reported that montmorillonite (MMT) nano-clay inside the PVA hydrogel resulted in a decrease in the swellability of PVA polymer in medium. However, in another study, the same group demonstrated that the rate of dehydration from the hydrogel reduced by adding MMT clay, suggesting that the clay preserved the water inside the hydrogel [36].…”

Removal of cationic dyes by poly(AA-co-AMPS)/montmorillonite nanocomposite hydrogel

“…These materials are commonly defined as combination of polymer matrix and additives that have at least one dimension in the nanometer range. Among clays, montmorillonite (MMT) was extensively used as a reinforcing filler in the preparation of hydrogel nanocomposites [19,20].…”

Nanoporous Nanocomposite Hydrogels Composed of Polyvinyl Alcohol and Na-montmorillonite

“…[24] Nanocomposite hydrogels are reinforced hydrophilic three-dimensional networks consisting of at least a cross-linked polymeric matrix and a nanoscale reinforcing agent. [25] Different types of nanostructured particles, e.g., gold, [26] silver, [27] iron oxide, [28] carbon nanotubes, [29] and various kinds of clays, e.g., laponite, [30,31] montmorillonite, [32,33] hydrotalcite, [34] and bentonite, [35] have been used to produce nanocomposite hydrogels. Nanocomposite hydrogels have been utilized successfully in numerous practical applications such as sensor and actuator systems, [36] oil recovery, [37] biomedical scaffolds, [38] drug delivery devices, [39,40] and wound dressing systems.…”