The influence of the content and structure of the inorganic component on the short-range order, degree of crystallinity, and permeability of the organic matrix of organo-inorganic (hybrid) nanocomposites based on linear polyimide and various ethoxysilanes, such as tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES), was considered using the methods of WAXS and radio spectroscopy at different component ratios. The nanocomposites based on linear polyimide (obtained by the interaction of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether) and an inorganic component obtained using TEOS, TEOS:MTES at a ratio of 1:1, and TEOS:MTES at a ratio of 1:2 were investigated. TEOS forms an inorganic network with the general formula (SiO2)n, MTES forms a looser inorganic network with the general formula (CH3SiO1,5)n. The ethoxysilane content was 5 wt.%, 20 wt.%, or 50 wt.%. The data for the composites were compared with the characteristics of the original polyimide. The data showed that the amorphousness of the polyimide matrix increased with an increased proportion of MTES. The data showed that the amorphousness of the polyimide matrix increased with an increased proportion of MTES. A correlation was found between the permeability of nanocomposites and a structural parameter that characterizes the relationship between crystallite size and the period of short-range ordering of the polymer.

In this work, the effect of the method of dispersion of a reactive N-phenylaminopropyl polyhedral oligomeric silsesquioxane (NPAP-POSS, 0.025 wt.%) with eight secondary amino groups, in dicyanate ester of bisphenol E (DCBE) on the chemical processes occurring in reactive DCBE/NPAP-POSS blends during dispersion, as well as on the chemical structure, viscoelastic, thermophysical, and thermal properties of heat-resistant organic-inorganic PCN/NPAP-POSS nanocomposites was investigated. The synthesis of the nanocomposite samples was carried out in two stages. In the first stage, to improve the efficiency of nanofiller dispersion, high-speed mechanical or ultrasonic mixing of NPAP-POSS with DCBE was used at different temperatures (T = 65 °C, T = 165 °C), which ensured the chemical interaction of the components. In the second stage, PCN/NPAP-POSS nanocomposites were synthesized by in situ high-temperature reactive molding by dynamic heating the samples in the temperature range of T = 20–300 °C. Using dynamic mechanical thermal analysis (DMTA) for PCN/NPAP-POSS nanocomposites synthesized by high-speed mechanical or ultrasonic mixing at a temperature of T = 65 °C, an unusually significant increase (by 26.5–28.5 °C compared to PCN) in the glass transition temperature (Tg) of the samples even at ultra-low NPAP-POSS content. This phenomenon demonstrates the so-called nanoscale effect. It was also found that the method of nanofiller dispersion affects the increase (compared to unfilled PCN) of the storage modulus (E’) and other viscoelastic properties, as well as the apparent network density (v) and the apparent average molecular weight (Mc) between crosslinks in the hybrid network matrix of the nanocomposites. Differential scanning calorimetry (DSC) also showed that the dispersion method changes the thermophysical properties of the synthesized PCN/NPAP-POSS nanocomposites. This effect is associated with the formation of additional organic-inorganic crosslinks due to the chemical embedding of NPAP-POSS nanoparticles and the formation of the hybrid PCN/NPAP-POSS network. Fourier transform infrared (FTIR), 1H NMR, and 13C NMR spectroscopy confirmed that during nanofiller dispersion in DCBE/NPAP-POSS reactive blends, a chemical interaction occurs between the –O–C≡N groups of DCBE and the secondary –NH groups of NPAP-POSS. This interaction is confirmed by the appearance of corresponding absorption bands and signals (chemical shifts) in the spectra indicating the formation of intermediate isourea fragments and triazine rings of polycyanurates. It was concluded that ultrasonic dispersion of the nanofiller is the most effective under these synthesis conditions for PCN/NPAP-POSS nanocomposites as it ensures the highest degree of cyanate group conversion in DCBE at the final stages of synthesis (confirmed by DMTA data), thereby extending the range of working temperatures within which the samples retain their mechanical and physical properties. Using thermogravimetric analysis (TGA), it was found that all nanocomposites exhibit high resistance to thermo-oxidative degradation (Td > 440 °C), which is largely unaffected by the method of nanofiller dispersion and is determined by the chemical structure of the densely cross-linked PCN/NPAP-POSS hybrid network.

Dynamic covalent bonds (DCBs) can be used as crosslinking points to induce self-healing and thermoplastic properties in hydrogels because the bonding and dissociation between molecules can be controlled by external stimuli. However, once DCBs dissociate, molecules diffuse inside the gel, delaying DCB reformation. In this study, a hydrogel was prepared via template polymerization using phenylboronic acid-coated nanoparticles to control the mobility of the molecules and the density of the DCB crosslinking points. Interestingly, the loss modulus, but not the storage modulus, of the hydrogel changed with temperature according to the formation/dissociation of boronic ester bonds. Furthermore, compared with conventional hydrogels, the hydrogels prepared here exhibited very rapid changes in physicochemical properties in response to changes in temperature because the high density of three-dimensional DCB crosslinking points limits the diffusion of molecules inside the gel. As a result, the prepared hydrogel showed rapid self-healing and thermoplastic properties as the temperature changed.

A method for the synthesis of protic polymeric ionic liquid (PIL) of a block oligomeric structure with ionic bonds in the main chain, which turns into a liquid state at temperatures below 50 °C, was developed. Ionic bonding was used to form a polymer chain. It was formed as a result of neutralization reaction between oligomers of telechelic structure with terminal acidic and basic groups. A new linear oligomer containing basic tertiary nitrogen atoms at the ends of the oligoether chain (PEO-2NEt2) was obtained by reaction of α,ω-diglycidyl ether of polyethylene glycol MW 1000 with N,N-diethylamine. A linear oligomer with terminal sulfonic acid groups (PEO-2SO3H), which is a product of the interaction of polyethylene glycol (MW 1000) with the cyclic anhydride of 2-sulfobenzoic acid, was used as an acidic linear oligomer. The synthesis of PIL [PEO-2H-2NEt2]2+ [PEO-2SO3]2- was carried out by neutralization of basic oligomer PEO-2NEt2 with the acidic oligomer PEO-2SO3H in their molar ratio of 1:1. The structure of the obtained compound was characterized by the methods of FTIR and 1H NMR spectroscopy. According to the DSC data, the synthesized PIL contains an amorphous phase with a glass transition temperature of -49.7 °С and a crystalline phase with a melting temperature of 34.5 °С. The decomposition onset temperature corresponding to 5% weight loss is 271 °C according to the TGA. The ionic conductivity of PIL studied by dielectric relaxation spectroscopy under anhydrous conditions in the range from 40 °C to 100 °C increases with increase in temperature and reaches 2.7·10-4 S/cm. The resulting compound is promising as a proton-conducting medium for various electrochemical devices.

Based on diisocyanate prepolymer (DPP), the series of polyurethane-urea (PUU) with fragments of polyvinyl alcohol-polyethylene glycol (PVA-PEG) graft copolymer and 4,4’-diaminodiphenylmethane (DADPh) macrochain extender in the structure at different molar ratios of DPP:DADPh:PVA-PEG (1.0:0.7:0.3; 1.0:0.8:0.2; 1.0:0.9:0.1) were synthesized. Composite materials with the drug dacarbazine (DAС) in the amount of 1.0 wt.% based on the obtained PUU were developed. Studies of the structure and properties of PUU and composite materials with DAC based on them were carried out. The immobilization of DAC was found to be due to intermolecular hydrogen bonds by means of IR spectroscopy. According to the results of physical-mechanical tests, the introduction of DAC into the composition of PUU causes a non-significant decrease in the physical-mechanical properties, which is probably associated with a decrease in the packing density of macrochains of the polymer matrix. According to DSC, the studied systems are single-phase with a glass transition temperature (Tg) ranging from -12.50 to -31.99 °C. The introduction of DAC into the composition of PUU causes an increase in Tg and the specific heat capacity at the values of the glass transition temperature, which can be caused by a change in chain mobility due to the introduction of the filler and is correlated with the data of physical-mechanical tests. According to the results of hydrophilicity studies the introduction of PVA-PEG graft-copolymer into the PUU structure and increasing its content leads to an increase in hydrophilicity, which will contribute to a prolonged release of DAC from the polymer matrix. Therefore, the obtained composites with DAC are promising materials that can be used in medical practice as biologically active polymeric materials with a prolonged effect of an anticancer drug.