Strontium-Induced Gelation of Sodium Alginate in the Presence of Carbon Nanotubes: Elemental Analysis and Gel Structure

Abstract

The elemental composition and structural features of the junction zones of a strontium–alginate hydrogel and their alteration under the intercalation of multi-walled carbon nanotubes into the hydrogel structure were studied. It was shown that the crosslinking with Sr2+ cations due to electrostatic interactions leads to the association of polymer chains into junction zones with incompletely filled cells. It was found that in strontium alginate, the average cell occupation number of Sr2+ cations is less than 1 and approximately equal to 0.64. In nanocomposite hydrogels including multi-walled carbon nanotubes, its increase to 0.81 indicates the appearance of a more ordered structure of alginate chains in junction zones. The information about the most preferred types of egg-box cells for binding with Sr2+ cations was analyzed. The existence of Sr2+ cations in nonequivalent positions was established. The possibility of separating the contributions of chemical adsorption due to ionic bonds with alginate chains and physical adsorption due to the appearance of local energy minima near alginate chains, leading to the appearance of ordered secondary structures, was demonstrated. It has been shown that the addition of carbon nanotubes to a hydrogel changes their sorption capability, leading, first of all, to an increase in the possible sites of physical adsorption.

Underused Marine Resources: Sudden Properties of Cod Skin Gelatin Gel

“…This makes it closer to the mammalian one by its rheological properties. Our previous experience in the field of complex hydrogel systems based on the interaction of gelatin with different marine polysaccharides, various metal cations and carbon nanomaterial [74][75][76][77][78][79][80] will help in the design of novel systems with broad technological potentials.…”

Ions-Induced Alginate Gelation According to Elemental Analysis and a Combinatorial Approach

“…In [56,57], Makarova and Zueva et al published some aspects of the association of alginate chains into junction zones when they are bound by cations of alkaline earth and some transition metals, considering peculiar features of the elemental composition of freezedried hydrogel microspheres. Our theoretical considerations were based on the egg-box model of ion-induced association of polysaccharide chains proposed in [50].…”

“…The purpose of this work was to generalize the method introduced by us earlier [56,57], based on combinatorial analysis, for the study of alginate gels formed by biopolymers with an arbitrary ratio µ = M/G. For this purpose, we developed an algorithm to correctly separate the contributions from cations located in nonequivalent positions, i.e., from physically adsorbed and structure-forming ionic compounds, scaling the obtained results to alginate C 12 block.…”