Mixtures containing polyvinyl alcohol (PVA) and methylcellulose (MC) were obtained and used to synthesize hydrogels in various ratios of components. The swelling kinetics of the resulting hydrogels were studied, revealing that the equilibrium swelling degree in artificial saliva is nearly twice as high as in water. It was found that increasing the volumetric content of PVA in the mixture leads to a higher swelling degree. The kinetics of active pharmaceutical ingredient (API) sorption and release from the hydrogels were also investigated. It was demonstrated that hydrogels with a higher PVA content exhibit greater sorption capacity; however, the release of the API from such samples occurs at a slower rate. For the first time, the mucoadhesive properties of PVA-MC-based hydrogels were studied. It was established that the PVA-MC hydrogel with a ratio of 6:4 vol.% remained on the surface of the porcine cheek mucosa for two days, the 5.5:4.5 vol.% sample detached after 24 h, and the 5:5 vol.% sample adhered for approximately 10 h. These findings confirm the mucoadhesive potential of the hydrogels and their suitability for buccal drug delivery forms. The synthesized PVA-MC hydrogels are promising for applications in medicine and pharmacology.

In this study, polymer films based on polyvinyl alcohol (PVA), modified starch, and acrylic acid (AA) were synthesized and characterized. For the first time, this work investigates the synergistic effect of incorporating AA into films based on PVA and preirradiated starch. Unlike conventional approaches that rely on simple blending of PVA and starch, the use of AA as a functional monomer enables the formation of a chemically cross‐linked structure, where the carboxyl groups of AA establish additional hydrogen and covalent bonds with the hydroxyl groups of PVA and starch, as confirmed by FTIR spectroscopy. Furthermore, this study employs starch that has been pretreated with electron beam irradiation, which enhances component compatibility and improves the mechanical and thermal properties of the films. A comprehensive analysis of the main physicochemical properties of the films showed that increasing the AA content led to a rise in gel fraction yield from 67.4% to 86.2%, indicating a denser cross‐linked polymer network. Thermogravimetric analysis demonstrated improved thermal stability with increasing AA content, with the decomposition temperature reaching up to 450°C and total mass loss reduced to 50%. Mechanical testing revealed a significant enhancement in strength and elasticity: The tensile strength increased from 300 to 500 kPa, and the Young’s modulus increased from 0.3897 to 0.5514 kPa. The obtained results suggest that PVA/starch/AA films hold great potential as a promising material for biodegradable packaging applications.

The continuous use of post-consumer polyethylene terephthalate (PET) waste remains a major challenge due to its environmental properties and the high energy requirements of traditional recycling methods. In this study, an energy-efficient and environmentally friendly route for the synthesis of p-phenylenediamine (PPD) from secondary PET waste was developed. Terephthalic acid was obtained from PET waste under simple conditions and then terephthalamide was obtained through a catalytic high-pressure ammonolysis process. The main part of the process involved the Hofmann rearrangement reaction, for which an environmentally friendly chlorinating agent was selected based on research. Various hypochlorite and dichloroisocyanurate salts were analyzed based on their active chlorine equivalents, reaction efficiency, safety, and waste profile. Among the tested reagents, sodium dichloroisocyanurate chlorinated amides to a high degree under alkaline conditions, reduced hazardous waste, and produced harmless by-products. As a result, p-phenylenediamine was obtained in 84% yield. The structure and properties of the synthesized product were confirmed by IR, NMR, TG, and DTA analyses. This research work demonstrates a green and efficient method for converting PET waste into valuable aromatic diamines. However, it also highlights the importance of choosing an environmentally friendly reagent for the Hofmann rearrangement reaction. Keywords: Polyethylene terephthalate (PET), ammonilysis, glycerin, sodium urea, dichloroisocyanurate salt, reactor autoclave, amination, terephthalamide.

Thermal insulating materials based on diatomite with burnable and reinforcing additives modified with synthetic and natural polymers have been developed. A mixture of polyvinyl alcohol and starch was used as modifying polymers. The parameters of linear shrinkage, density, tensile strengths in compression and bending, as well as the coefficient of thermal conductivity of the material were determined depending on the concentration and ratio of polymers. It was established that polymer additives had a positive effect on almost all specified characteristics of thermal insulating materials. For example, when adding polymers up to 1 mass.%, the linear shrinkage coefficients decrease from 14.5 to 4.5%, the ultimate compression strengths increase from 0.22 to 2.51 MPa, the ultimate bending strengths increase from 0.2 to 1.26 MPa, the coefficients of thermal conductivity decrease from 0.068 to 0.049 W/m∙K. The densities of materials are in the range of 0.592-0.491 g/cm3. The results of the work showed that the obtained heat-insulating materials can be used as plasticizers in the field of thermal energy.