Carbon Nanotubes in Composite Hydrogels Based on Plant Carbohydrates

Abstract

Due to the physical, chemical, biological characteristics and high biocompatibility, the hydrogels based on plant polysaccharides and proteins became a sought-after material in many fields. Such hydrogels are the water swelling biopolymer matrices that react reversibly on minor changes in composition and in the external environment. However, the mechanical and electrical properties of "pure" hydrogels inhibit their wide practical application. One of approachs to improve their properties is the usage of carbon nanotubes, which provide good electrical conductivity and can significantly improve the characteristics of materials. The effects of carbon nanotubes on electric conductivity and mechanic properties of hydrogels based on natural biopolymers (gelatin and κ-carrageenan) of different composition were investigated. The electrical conductivity of the gels was studied using InoLab Cond 7310 SET1 conductometer. The rheological properties of hydrogels were investigated by Anton Paar MCR 302 rheometer. Such characteristics as temperature, frequency and amplitude dependencies of the storage modulus and the loss modulus of hydrogels were obtained. It was found that the addition of carbon nanotubes led to the increase in electrical conductivity of hydrogels. The morphology and rheological properties of studied hydrogels alter significantly in the presence of carbon nanotubes. The obtained data indicate the possibility of a purposeful change in electrical and mechanical properties of hydrogels by the addition of carbon nanotubes.

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

“…To prepare solutions, we used ultrapure water purified with the "Arium mini" water purification system (Sartorius, Göttingen, Germany). An aqueous solution of sodium alginate (2 wt.%) was prepared according to standard methods [16,56,94,95]. When a hot (70 • C) solution of sodium alginate was dripped into a concentrated solution of divalent metal salt (1 M) at a temperature of 20-23 • C, microspheres of composite hydrogels with a diameter of about 2 mm were instantly formed, in which monovalent sodium ions were replaced by divalent metal ions.…”

Use of Natural Biopolymers to Create Nanocomposite Materials

“…Hydrogels are obtained on the basis of hydrophilic synthetic or natural polymers. [8][9][10][11][12][13][14][15][16][17][18][19]. They are spatial three-dimensional networks created from bonded polymer chains that can hold large amounts of water.…”

“…Promising materials for creating modern hydrogels are mixtures of gelatins with polysaccharides [12][13][14][15][16][17][18][19], for example, with κ-carrageenan [12][13][14][15][16], sodium alginate [17,18], chitosan [19], and others. Macromolecules of biopolymers, due to the presence in their composition of various active groups capable of forming bonds of various types, form intermolecular complexes and supramolecular structures.…”

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

“…When drops of sodium alginate enter a concentrated solution of strontium chloride salt, the neighboring polymer chains are connected due to the formation of ionic bonds, coordination and complexation between strontium ions and the carboxyl groups of alginate chains, leading to the transformation of solution droplets into gel microspheres [34,35]. Modification of solutions used by the addition of nanoparticles and the creation of composite hydrogels can significantly transform the properties of developed materials and expand the scope of their possible application [20,[36][37][38][39][40].…”