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The hydrogels based on cross-linked dextran-graft-polyacrylamide (D-g-PAA) and polyacrylamide (PAA) with different densities of chemical cross-links were synthesized by radical polymerization. They were used as nanoreactors for the photochemical synthesis of silver nanoparticles (AgNPs). The polymer hydrogels and nanocomposites with loaded AgNPs were characterized by SEM, FTIR- and UV–Vis spectroscopy. Swelling studies demonstrated differences in the internal structure of the cross-linked D-g-PAA and PAA samples. The morphology of the hydrogels affects the properties of the obtained nanocomposites. The microbiological tests have shown that the D-g-PAA-based hydrogels loaded with AgNPs are more active against Staphylococcus aureus than their PAA-based counterparts and can be an efficient alternative to antibiotic-containing coverings and dressings.

The multi-component nanosystems based on the branched copolymer dextran-graft-polyacrylamide in an anionic form (D-g-PAAan) with gold nanoparticles (AuNPs), photosensitizer Chlorine e6 (Ce6), and chemotherapeutic agent Doxorubicin (Dox) were developed for use in complex breast cancer therapy. The synthesized nanosystems were characterized by Quasi Elastic Light Scattering and Transmission Electron Microscopy and tested against the malignant cells MCF-7/Dox resistant to Dox. It is found that the addition of Dox as the fourth component to the three-component nanosystem D-g-PAAan/AuNPs/Ce6 leads to aggregation and, as a result, to decrease in efficiency of tumor treatment. The way to reduce unwanted aggregation in the four-component nanosystem D-g-PAAan/AuNPs/Ce6/Dox is proposed. The new nanosystems are shown to be effective in overcoming Dox resistance and killing cancer cells.

Because of the low content of chelating groups onto carbon fibers (CFs), their adsorptive parameters are poor, and this has negative effects on their applications as lightweight sorbents. In this work, we established a modification method to incorporate amine groups into carbon fiber surfaces by bromination followed by ammonolysis to create an interfacial layer which can adsorb heavy metal ions from solutions. The changed chemical composition, surface morphology, and thermal stability were investigated. Thermoprogrammed desorption mass-spectrometry and thermal analysis showed thermal transformation and interplay between forms of the grafted bromine groups of 0.5 mmol/g and the resulting amino groups of 0.44–0.56 mmol/g. After grafting, the surface chemistry parameters were improved due to the covalent bonding and grafting of the amine groups as interface modifier. Scanning electron microscopy observation also confirmed that the surface morphology maintains the same, without impairment of fiber properties. This work is therefore a beneficial approach towards enhancing the adsorption parameters by controlling the interface layer of CFs.

The functionalization of the carbon fiber based on polyacrylonitrile with sulfur-containing groups of high acidity was carried out in order to obtain the acid-base processes catalysts. Fibers were treated with sulfur vapors in the temperature range of 400-800°C, followed by surface oxidation with 30% hydrogen peroxide solution. Modified samples were investigated by chemical analysis, thermo-programmed desorption with mass spectrometric registration of products, IR spectroscopy and thermogravimetry. It is shown that the obtained materials contain SO3H-functional groups and oxygen-containing groups (carboxyl, lactone, phenolic, etc.) formed in the surface layer during the oxidation of the fiber surface. The chemical analysis showed that the concentration of sulfur in the samples of the modified fiber is 1.6-6.5 mmol/g. The synthesized samples have a satisfactory thermal stability. The synthesized catalysts were investigated in the model reaction - gas phase dehydration of isopropyl alcohol. It was found that obtained SO3H-containing carbon fibers were catalytically active and had high propylene selectivity. For all the samples obtained there is a complete conversion of alcohol into propylene. The activity of modified carbon fiber samples in the reaction indicated is a fairly high, temperatures of the total conversion of alcohol into propylene are in the range of 160-190°C. During the study of synthesized catalysts in several cycles of catalysis it have been shown that within repeated use (3 cycles) of all modified fiber samples, the yield of propylene does not decrease, the activity remains stable - the temperature of the dehydration reaction remains unchanged or increases insignificantly (by 5-10ºС). The temperatures of complete conversion of isopropyl alcohol in propylene for synthesized catalysts are lower than the temperatures of destruction maxima of surface sulfogroups. Thus, modified carbon fibers can be used as low-temperature catalysts of acid-base processes, in particular dehydration of alcohols.

The production of propylene by dehydration of 2-propanol at solid-vapor interfaces, as an example of the acidcatalyzed surface reaction, was explored by using sulfonated polyacrylonitrile-derived activated carbon fibers (PAN-ACFs). To prepare these catalysts, the PAN-ACFs obtained by onestep carbonation-activation were modified with a surface coverage of high acidity. The surface of PAN-ACFs was sulfurated with sulfur vapors at high temperatures followed by oxidation, to yield the corresponding sulfonates. The chemical analysis showed that the carbon surface layer contains from 1.28 to 6.10 mmol$\mathrm{g}^{-1}$ of sulfur, including the contribution of sulfonic $(\mathrm{S}\mathrm{O}{}_{3}\mathrm{H})$ groups. In addition to sulfonic groups, the obtained catalysts contain carboxyl, lactone, and phenolic groups, which are formed as a result of oxidation treatment. In order to understand the changes in surface chemistry and the results of sulfuration and oxidation, the sulfonated PAN-ACFs were characterized by a variety of techniques including TPD MS, TGA, SEM, and FTIR ATR. During a typical temperature mode screening at catalyst testing, it was found that the sulfonated PAN-ACFs prepared by treatment with sulfur vapor at low temperature, at $400\circ \mathrm{c}$ and $500\circ \mathrm{c}$, are very efficient at dehydrating 2-propanol. A weighed mass of 100 mg of each of these catalysts was operated at 165-175°C in 12 hours, and the catalysts were characterized by high conversion of 2-propanol and high selectivity to propylene, with a propylene yield of about 100%. Furthermore, the solid acid catalysts have high stability and strong acidity and can be reused with no significant loss in the activity after the third cycle in the subsequent 20 cycles. The preparation of solid acid catalysts from PAN-ACFs affords a novel strategy for producing propylene through alternative green and sustainable technologies.

We proposed the brominated carbon cloth that made of polyacrylonitrile-based activated carbon fibers (PAN-ACFs) as a precursor to chemically and uniformly graft SO3H groups to prepare the solid acid catalyst. The thermal and catalytic properties of the sulfonated PAN-ACFs were examined by IR controlled catalytic measurements and thermal analysis. The catalytic test results showed that the sulfonated surface remarkably improved the operating efficiency in isopropanol dehydration by decreasing the reaction temperature. All PAN-ACFs with grafted SO3H groups prepared through brominated precursors can converse 100% of isopropanol into propylene at moderate temperature. They showed the highest catalytic activity compared to PAN-ACFs sulfonated with oleum and chlorosulfonic acid, which conversed only 40% and 70% of isopropanol into propylene and deactivated at the higher temperatures in the reaction medium.

Nanoporous activated carbon fibers (BusofitTM, BACF) showed effective adsorption of carbon tetrachloride (CTC) vapors. About 2.50 mmol × g−1 of chlorine, in the form of trichloromethyl and ...

Multicomponent nanocomposites for anticancer therapy were prepared, characterized, and tested for their antitumor efficacy. The water-soluble star-like dextran-graft-polyacrylamide copolymer was used as a nanoplatform for the creation of polymer-based multicomponent drug delivery systems for photodynamic and combined (photodynamic+chemotherapy) antitumor therapy. The three-component nanocomposites with incorporated gold nanoparticles and photosensitizer and the four-component ones additionally loaded by Doxorubicin into polymer nanoplatform were studied at 25 and 37°C by transmission electron microscopy and dynamic light scattering. Nanocomposites were tested for their photodynamic cytotoxicity for the cell line of breast cancer MCF-7/S. Three-component nanocomposites demonstrated higher efficacy than the four-component ones. The decrease in the activity of the four-component systems is explained by the aggregation process caused by the introduction of an additional component, which leads to a decrease in the hydrophilic-hydrophobic balance of the polymer macromolecule.

Hydrogels loaded with silver nanoparticles are promising materials for biomedical antibacterial application. This work was focused on the synthesis of hydrogel–silver nanocomposites based on Dextran-graft-Polyacrylamide copolymers in non-ionic and anionic form. A photochemical synthesis of colloidal silver particles through Ag seed-mediated growth under the UV solar radiation was carried out. All nanocomposites have revealed an absorption peaks at 420 nm corresponding to silver nanoparticles (AgNPs) Plasmon absorbance. However, the character of the absorption bands was dependent on the condition of AgNPs synthesis and chemical nature of polymer hydrogel. The obtained nanocomposites demonstrated high antibacterial efficiency against Escherichia coli and Staphylococcus aureus.

The thermal resistivity method, which is a convenient and sensitive to electrical resistance changes, was proposed for control of chemical modification of nanoporous activated carbon fibers (NACF) with hydrofluorocarbons (HFC). The surface state changes could be monitored by measuring Ohmic resistance during heating, physisorption, and chemical reaction between the activated carbon material and HFC. Thus, we found a correlation between the fluorine content in the resulted carbon material and electrical resistance, measured from the room temperature to 900 °C. It was shown that in this way the temperature of the beginning of a chemical reaction and the temperature of the most effective chemical modification could be determined. The thermal grafting of fluororganic groups onto NACF is assumed to be the reason for the changed electrical resistivity of the initial NACF.

Activated carbon fibers (ACFs) made from polyacrylonitrile and viscose were treated with the sulfur vapor at the temperatures of 500–800 °C in an argon flow. Obtained materials were oxidized by 30% H 2 O 2 water solution in order to convert S-containing surface moieties into SO 3 H-groups. The samples were studied using Boehm titration, thermogravimetric analysis and temperature-programmed desorption with a mass spectrometric registration of gaseous desorption products. According to obtained data, the surface layer of synthesized samples contains grafted SO 3 H-groups and different functional groups formed at the carbon oxidation. The decomposition of SO 3 H-groups occurs in the temperature range of 75–590 °C. Two peak maxima at 200±30 °C and 300±30 °C were registered on all SO 2 desorption profiles. These maxima are assigned to two forms of surface SO 3 H groups having a different chemical environment. Testing of the catalytic activity shows that SO 3 H-functionalized carbon fibers are high active in the model reaction of propan-2-ol dehydration. The total conversion of propan-2-ol to propene is observed at 145–220 °C. The lowest temperature of total conversion was registered for the ACFs prepared from polyacrylonitrile being treated with the sulfur vapor at 500 °C. All SO 3 H-functionalized samples maintain their activity after repeated use.

Branched copolymers Dextran-graft-Polyacrylamide (D-g-PAA) with star-like architecture of macromolecules and linear Polyacrylamide (PAA) were used for in situ synthesis of Ag nanoparticles. Aqueous silver colloids were characterized by UV-vis spectroscopy, TEM and dynamic light scattering. The internal structure of polymer matrices in solution affects the Ag nanoparticle formation and stability of colloid systems. Branched structure of D-g-PAA macromolecules provides obtaining of stable silver colloids even at high temperature when linear PAA matrix is not efficient.

Summary: Star-like dextran-graft-(polyacrylamide-co-polyacrylic acid) (D-g-(PAA-co-PAAc) copolymers in a salt form were obtained by alkaline hydrolysis of Dextran-graft-Polyacrylamide (D-g-PAA) samples. The internal structure of D-g-PAA insolution predetermined the reaction course and the conversion degree dependedupontheinitial architecture ofmacromolecules.Itwasshownthatmacromoleculesof D-g-(PAA-co-PAAc) acquired extended conformation because grafted chainsbecame greatly straightened when charged functional groups appeared. Nopolyelectrolyte effect for synthesized D-g-(PAA-co-PAAc) samples was registered.Star-like polyelectrolytes were proved to be more efficient matrices in comparisonwith linear anionic Polyacrylamide for silver nanoparticle in situ synthesis. Keywords: nanoparticles; non-linear polymers; polyelectrolytes Introduction Polyelectrolytes with non-linear architec-ture of macromolecules attract a warminterest due to their unusual propertiesarisen from peculiarities of their internalstructure in solution. This structuredepends on chemical nature of polymer,length of branches and distance betweenthem,amountanddistributionoffunctionalgroups along chains, construction mode ofbranched molecule. A lot of variableparameters (pH, ionic strength, chemicalnature and charge of counterions, temper-ature, etc.) affect the properties of poly-electrolytesolutionsotheyhavetobetakeninto account when non-linear ionic poly-mersareappliedastask-oriented materials.Nowadays linear Polyacrylic acid(PAAc) and Polyacrylamide (PAA) innonionic and anionic forms are widely usedin water treatment, biotechnology, medi-cine, pharmacology.

Branched dextran-graft-polyacrylamide copolymers (D-g-PAAn) with different number of PAA-grafts have been synthesized for further conversion them to polyelectrolytes dextran-graft-(polyacrylamide-co-polyacrylic acid). It is shown that D-g-PAAn internal structure in water solution is more compact in comparison with linear polyacrylamide and depends upon the distance between PAA grafts. The branched polyelectrolytes are obtained by alkaline hydrolysis of synthesized D-g-PAAn samples. The conversion of nonionic polymers to partial anionic form depends upon the macromolecular internal structure of D-g-PAAn. The degree of transformation of amide groups to carboxylate ones is higher for branched copolymers than for linear PAA at the same condition. The synthesized branched copolymers are shown to be perspective as flocculation agents and the matrices for synthesis of the stable Ag nanosystems.

The Silver nanoparticles were synthesized in water-soluble polymer matrices Dextran, linear Polyacrylamide, branched copolymers Dextran-graft-Polyacrylamide and DNA. The silver nanoparticles size depends on the matrix nature and internal structure of macromolecules in solution.