Bionanocomposites formed by in situ charged chitosan with clay

Abstract

Bionanocomposites are formed through the electrostatic interactions of exfoliated clay nanoparticles initially dispersed in an aqueous solution with chitosan macromolecules that are gradually charged in the course of a progressive pH decrease by chemical acidulating agent to exclude the phase separation.Chitosan is a product of the de-acetylation of chitin, which is the second abundant organic compound on Earth after cellulose. Although this polysaccharide presents a huge renewal resource of biomass, of which annual production in nature reaches 100 billion tonnes, it is still almost unutilized, being a biopolymer of significant versatility and promise. 1-3 Clay is a natural mineral that is widely used for making various materials and in many industrial processes. Clay nanoparticles of smectite-type, such as montmorillonite and saponite, dispersed into polymers remarkably improve their material properties including strong reinforcing, increased heat resistance, decreased gas permeability and flammability. 4,5 Their effect is observed after exfoliation into

Chitosan bionanocomposites prepared in the self-organized regime

“…It provides only partial improvement of homogeneity along with deteriorative effects including the disruption of macromolecules. Our method suggested in [21,23] obviates the above-mentioned problems by relying on the property of weak polyelectrolytes to be in a charged or non-charged state. It depends on the pH of an aqueous solution [30].…”

“…Hydrogel preparation was followed the procedure developed in [23,25]. Briefly, ground fine microparticles of chitosan were added into an initially prepared solution of nanoparticle dispersion.…”

“…It was demonstrated that the formation of bionanocomposites proceeded in a self-organizing manner [2,26]. When it took place in a solution, one could see its jellification owing to a three-dimensional fibrillar network generated by chitosan with saponite [23,25], whereas films had two-level hierarchical stratified structure from micrometer-sized plates made up of alternating layers of nanoplatelets and polysaccharide macromolecules [26].…”

“…Our first studies have been performed with synthetic saponite belonging to the smectite family of clays [23,25,26]. It was demonstrated that the formation of bionanocomposites proceeded in a self-organizing manner [2,26].…”

“…This disadvantage was turned into virtue in our recent novel approach in which chitosan electrostatic interactions with anionic substances and nanoparticles were regulated via its charging [21,23,24]. As a weak polyelectrolyte, it can be in charged and non-charged forms ( Fig.…”