Biocompatible Interpenetrating Network Hydrogels with Dually Cross-Linked Polyol Ulygbek B. Tuleuov, Alexander L. Kwiatkowski, Akerke T. Kazhmuratova, Lyazzat Zh. Zhaparova, Yermauyt Nassikhatuly, et al. Polymers, 2025 Modern tissue regeneration strategies rely on soft biocompatible materials with adequate mechanical properties to support the growing tissues. Polymer hydrogels have been shown to be available for this purpose, as their mechanical properties can be controllably tuned. In this work, we introduce interpenetrating polymer networks (IPN) hydrogels with improved elasticity due to a dual cross-linking mechanism in one of the networks. The proposed hydrogels contain entangled polymer networks of covalently cross-linked poly(ethylene glycol) methacrylate/diacrylate (PEGMA/PEGDA) and poly(vinyl alcohol) (PVA) with two types of physical cross-links—microcrystallites and tannic acid (TA). Rheological measurements demonstrate the synergistic enhancement of the elastic modulus of the single PEGMA/PEGDA network just upon the addition of PVA, since the entanglements between the two components are formed. Moreover, the mechanical properties of IPNs can be independently tuned by varying the PEGMA/PEGDA ratio and the concentration of PVA. Subsequent freezing–thawing and immersion in the TA solution of IPN hydrogels further increase the elasticity because of the formation of the microcrystallites and OH-bonds with TA in the PVA network, as evidenced by X-ray diffraction and ATR FTIR-spectroscopy, respectively. Structural analysis by cryogenic scanning electron microscopy and light microscopy reveals a microphase-separated morphology of the hydrogels. It promotes extensive contact between PVA macromolecules, but nevertheless enables the formation of a 3D network. Such structural arrangement results in the enhanced mechanical performance of the proposed hydrogels, highlighting their potential use for tissue engineering.
Synthesis of Water-Soluble Polyethylene Glycol Fumarates for Biomedical Applications Yerkeblan M. Tazhbayev, Akerke T. Kazhmuratova, Lyazzat Zh. Zhaparova, Ulugbek B. Tuleuov, Yermauyt Nassikhatuly, et al. Eurasian Journal of Chemistry, 2024 Polyethylene glycol fumarate (PEGF) with controlled structural composition has been obtained for further synthesis of double network crosslinked hydrogels for biomedical applications. The copolymer has been synthesized by polycondensation reaction of fumaric acid and polyethylene glycol (PEG-600). Molecular weight of PEGF has been determined by gel permeation chromatography to be approximately 6000 Da with gel permeation chromatography. The polycondensation of fumaric acid and PEG-600 was studied throughout the reaction process. The structure of the reaction product has been evidenced using FTIR- and 1H NMR-spectroscopy. The quantitative ratios of the amount of –C=C– bonds and –COO groups to –C=O groups in the obtained PEGF have been estimated from IR-spectra for different synthesis time. The time-dependence of molar ratio of double bonds to methyl groups in PEGF has been obtained from corresponding 1H NMR-spectra. FTIR and 1H NMR-spectroscopy, both, demonstrate that after the end of reaction the unsaturated –C=C– double bonds remain in the structure of the macromonomer, that is essential for further preparation of cross-linked hydrogels. The addition of the tightly cross-linked network of polyvinyl alcohol leads to formation of highly tough biocompatible material for preparation of the artificial meniscus which can further be used as a solution n the treatment of diseases such as osteoarthritis.
The Effect of Liquid Active Media on the Character of Equilibrium Swelling of Copolymers Based on Polypropylene Fumarate Phthalate with Acrylic Acid Akmaral Zh. Sarsenbekova, Meyram Zh. Burkeyev, Gaziza M. Zhumanazarova, Gulshakhar K. Kudaibergen, Yermauyt Nasikhatuly, et al. Eurasian Journal of Chemistry, 2023 The article is devoted to the study of the influence of external factors on copolymers based on poly(propylene fumarate phthalate) with acrylic acid. In the present work, the effect of low-molecular salts on the swelling rate of the synthesized copolymers was studied. The surface morphology was examined using SEM. The swelling rate of the studied polymers depends on many factors, including the nature of the polymer and the solvent, the presence of electrolytes, changes in pH and ambient temperature, the molecular weight of the polymer, etc. It is assumed that the polymer network of copolymers mainly consists of links of unsaturated polyester resin. The results show that the ratio of monomer units in the copolymer significantly affects the susceptibility of the polymer gel to the presence of low-molecular salts. Changing the properties of the comonomer has been shown to produce hydrogels that can swell or collapse due to changes in ionic strength or the thermodynamic quality of the solution. By varying the ratio of the comonomeric units, the intervals of swelling and contraction of polymer meshes inherent in polyelectrolyte bodies with the same charges were adjusted. It was also found that the polymers under consideration belong to anionic meshes.
Comparative Analysis of Thermal Decomposition Kinetics of Copolymers Based on Polyethylene Glycol Fumarate with Methacrylic Acid Ulygbek B. Tuleuov, Akerke T. Kazhmuratova, Abylaihan N. Bolatbay, Ermaut Nassikhatuly, Aizhan R. Koishugulova, et al. Eurasian Journal of Chemistry, 2023 The thermal properties of a copolymer based on polyethylene glycol fumarate with methacrylic acid in a nitrogen atmosphere were studied in this paper. Four various heating rates and two types of a polyester resin composition were used. The analysis of thermal decomposition kinetics was implemented. Three kinetics methods namely Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Friedman were applied. Curves of a thermogravimetric analysis demonstrated that the thermal decomposition of copolymers with different molar ratios was observed. It was determined that the kinetic data depends on the studied copolymers’ composition. The obtained data showed a good convergence in various heating rates. Also, the thermodynamic characteristics were calculated namely the changes in the Gibbs energy (ΔG), enthalpy (ΔH) and entropy of activation (ΔS). The Achar-Brindley-Sharp method was used to find the invariant kinetic parameters of decomposition. Thus, the the kinetic compensation effect was applied to define a reaction model and a pre-exponential factor. A main phase of the copolymer decomposition in a narrow temperature range was determined. It was attested by a peak on the differential curve. An insignificant mass loss of the volatile-matter yield was observed in the range of 30–150 °C.
Study of thermal stability and determination of effective activation energy values during degradation of unsaturated polyester copolymers in the air atmosphere A.Zh. Sarsenbekova, A.N. Bolatbay, V.V. Morgun, D. Havlicek, S.Zh. Davrenbekov, et al. Bulletin of the Karaganda University Chemistry Series, 2022 The study of the kinetic parameters of copolymers based on polyethylene glycol fumarates, as well as the external and internal effects on them, is essential for production processes at various levels. This will solve a whole range of issues in the field of the shelf life of materials and storage conditions. All these point to the relevance of this research. The authors of the research attempt to test the most common thermogravimetric data processing methods and to improve them in terms of the quality of the predictive capabilities of the resulting regression equation. Both of them are important for the production of initial components and the manufacture of the final product from the studied materials. Therefore, the study and further use of the numerical data of the TG/DTA curves applies to both theoretical and practical branches of science. Thus, summarizing the experimental data on the thermal stability studies, we assume that p-EGF: AA copolymers with compositions of 21.03:78.97 and 68.96:31.04 wt.% have a relatively high degree of resistance to heating. It was found that the calculation by the FR method agreed well with the results of the KAS method. It should be noted that for the p-EGF: AA copolymer (21.03:78.97 wt.%) at heating rates of 5.0, 10.0, 20.0 °С∙min–1, the average activation energy data obtained for two methods increase in the following series:KAS E = 187.34 kJ /mol <FR E = 200.17 kJ/mol.
Study of Thermal Decomposition of the Copolymer Based on Polyethylene Glycol Fumarate with Acrylic Acid Meyram Burkeyev, Yerkeblan Tazhbayev, Abylaikhan Bolatbay, Yelena Minayeva, Santay Davrenbekov, et al. Journal of Chemistry, 2022 Thermal decomposition of the copolymer based on polyethylene glycol fumarate with acrylic acid (p-EGF:AA) at four different heating rates in a nitrogen atmosphere has been investigated by the dynamic thermogravimetry (TGA) method. The TGA curves show that the decomposition process occurs in several stages. The experimental data processed by the Kissinger–Akahira–Sunose and Friedman isoconversion methods made it possible to calculate the activation energy of the main decomposition stage. According to the calculations results, one can see that the values found by these methods do not strongly depend on the conversion. The Achar–Brindley–Sharp method has been applied to determine the compensation parameters. Then, using the compensation effect, the invariant kinetic parameters of the decomposition processes have been found. An experimental curve has been plotted to find the reaction model in comparison with theoretical ones.
