PREPARATION OF CHITOSAN GRAFT COPOLYMERS AND STUDY OF THEIR WATER-SWELLING PROPERTIES

In this work, graft copolymers of chitosan with trimethylmethacryloxyethylammonium methyl sulfate were synthesized by the method of controlled radical polymerization, and it was found that replacing the dimethylformamide aprotic solvent with water increases the degree of grafting. With the aim of the possible use of chitosan copolymers as a functional component for regulating the water-swelling properties of elastomers, the kinetics of swelling of the samples was investigated. An increase in the degree of swelling of the copolymers in comparison with the initial chitosan was revealed, and the influence of the molecular weight and the conditions of their synthesis was established.

Kinetics of Swelling of Cylindrical Temperature-Responsive Hydrogel: A Semi-Analytical Study

Cylindrical hydrogels have a wide variety of applications, especially in microfluidics as micro-valves, micro-mixers, and micro-lenses. Main advantages of them can be mentioned as their simple geometry and autonomous functionality due to their responses to the environmental stimuli. In current research, kinetics of swelling, shrinking and force generation of cylindrical temperature-responsive hydrogels have been investigated analytically. According to this, models of fluid permeation and large deformation of the hydrogels were considered and an analytical solution was performed. In order to study the behavior of the cylindrical hydrogels, the temperature is changed between higher and lower of the phase transition temperatures, and kinetics of the swelling and shrinking of the hydrogel have been studied and the distribution of stresses, stretches, water concentration and chemical potential are presented throughout the process. In addition, to investigate the behavior of the actuators, the cylindrical hydrogel is placed inside a hollow permeable pillar and the pressure of the hydrogel which puts on the pillar is studied. Ultimately, a comprehensive study on the effects of different parameters, namely, amount of temperature change, cross-link density and geometry, is conducted and the results are presented, which can be utilized in the design procedures of such actuators.

МОДИФИЦИРОВАНИЕ КОЛЛАГЕНА И ЖЕЛАТИНА ПОД ДЕЙСТВИЕМ МИКРОВОЛНОВОГО ПОЛЯ

The microwave field influence on the physicochemical properties of collagen and gelatin was studied. It is shown that when microwave field acts on the studied protein samples, a change in the molecules structure formation occurs. It was experimentally established that microwave exposure leads to the structural modification of collagen and gelatin molecules. This modification is accompanied by a change in the physicochemical properties of the studied biopolymers. It is shown that microwave field exposure leads to a decrease in the viscosity of collagen and gelatin solutions. A decrease in viscosity indicates that there’s a structural or transient processes occurring in protein molecules.The kinetics of swelling with time for collagen and gelatin samples was studied. It is shown that the use of a microwave field leads to a decrease in the rate constant of swelling. The swelling degree of the studied samples decreases on average by 60%. It is shown that isoelectric points of the proteins are shifted (pI from 5 to 6 for collagen and up to 5.5 for gelatin).

Investigation of the Swelling and Network Parameters of Epoxy Coatings Containing Polyaniline

The kinetics of swelling of epoxy coatings modified with polyaniline is investigated. The influence of the three-dimensional solubility parameter, the dielectric permeability, and the molar volume of solvent on the swelling of epoxy polymer coatings is shown. The parameters of the three-dimensional network for epoxy coatings modified with polyaniline are calculated.