Marina P. Filatova

A series of antimicrobial protonated diallylammonium polymers, poly(diallylammonium trifluoroacetate) (PDAATFA), were synthesized by classical polymerization, using an especially elaborated method for preparation of polymers with low molecular weight (MW), and by RAFT polymerization, with different end groups in a range of MW values of (8–43) × 10³ g∙mol⁻¹. Cytotoxicity relative to eukaryotic cells (epithelioid lines A-549 and MA-104) and bactericidal activity of the polymers (relative to Pseudomonas aeruginosa and Staphylococcus aureus) are investigated. The effect of the end groups and MW on toxicity and bactericidal activity is shown. Dependence of the activity and, most of all, cytotoxicity on MW is preserved even at a small difference in MW values in the MW range of (18–40) × 10³ g·mol⁻¹. A clear dependence of the studied properties on the nature of the terminal group is revealed. Sulfate -O-S(=O)₂-O¯ end group has a noticeable effect on the bactericidal efficiency and smaller influence on toxicity, while dithiocarbonyl end group -S-C(=S)-O-CH₂-CH₃ has a significant effect on efficiency and especially toxicity, drastically increasing the latter. Overall, based on the results obtained, polymers PDAATFA of low MW are considered promising antimicrobial agents for the creation of new transdermal drugs.

A series of antimicrobial protonated diallylammonium polymers, poly(diallylammonium trifluoroacetate) (PDAATFA), have been synthesized by classical polymerization, using especially elaborated method for preparation of polymers with small molecular weight (MW), and by RAFT polymerization, with different end groups in a range of MW values of (8 – 35)x10^3 g∙mol-1. Cytotoxicity relative to eukaryotic cells (epithelioid lines A-549 and MA-104) and bactericidal activity of the polymers were investigated. The effect of end groups and MW on toxicity and bactericidal activity has been shown. Dependence of the activity and, most of all, cytotoxicity on MW is preserved even at a small difference in MW values (10^4 gxmol-1) in the MW range of (18-35)x10^3 gxmol-1. A clear dependence of the studied properties on the nature of the terminal group has been revealed. Sulfate -O-S(=O)2-O¯ end group has a noticeable effect on the bactericidal efficiency and smaller influence on toxicity, while dithiocarbonyl end group -S-C(=S)-O-CH2-CH3 has significant effect on efficiency and especially toxicity, drastically increasing the second. In a whole, based on results obtained and considering toxicity values obtained for the MA-104 cell line, polymers PDAA of small MW seem to be promising as antimicrobial agents for the creation of new transdermal drugs.

Protonated diallylammonium polymers attract attention due to a number of properties, in particular high antimicrobial activity, including activity against the mycobacterium M. tuberculosis. To reduce the cytotoxic effect of polymers in the case of practical use, samples with a low MW are required. The work investigated the free radical polymerization of protonated diallylammonium monomers, diallylammonium trifluoroacetates, in excess of the initiator ammonium persulfate (10^–1 M) and at average polymerization temperatures (40 and 50°C) to obtain polymers with a low degree of polymerization. It has been shown that under such conditions it is possible to obtain polymers with values suitable within the aim: 16000 < MW < 28000 g/mol. Using NMR and IR spectroscopy, it was shown that with an increase in the concentration of the initiator and, accordingly, a decrease in the molecular mass of polymers, the relative number of characteristic terminal vinyl groups decreases, and the terminal groups formed by the interaction of macroradicals with primary radicals of the initiator become predominant, in this case, sulphate groups of ammonium persulfate. The data obtained indicate that at high concentrations of the initiator, the characteristic reactions of chain transfer to the monomer are largely kinetically suppressed by the interactions of macroradicals with the primary radicals of the initiator. The approach used, which makes it possible to synthesize polymers with a low MW and terminal groups of the initiator, can be applicable in the future to vary the properties of antimicrobial activity and toxicity of polymers.

In this work, PPSUs with different molecular weights were synthesized for the development of highly permeable ultrafiltration hollow fiber membranes for the first time. The M_W of the synthesized polymers was controlled by varying the monomers molar ratio within 1:1–1.15 under the same synthesis conditions. Based on the study of the rheological properties of polymer solutions, a high molecular weight PPSU (M_W = 102,000 g/mol) was chosen for the formation of hollow fiber membranes. The addition of PEG400 to the spinning solution led to an increase in viscosity, which makes it possible to work in the region of lower PPSU concentrations (18–20 wt. %) and to form membranes with a less dense porous structure. With the addition of PEG400 to the spinning solution, the membrane permeance increased sharply by more than two orders of magnitude (from 0.2 to 96 L/m²·h bar). At the same time, the membranes had high rejection coefficients (99.9%) of Blue Dextran model filtered substance (M_W = 69,000 g/mol).

A series of novel copolyesters based on polyethylene terephthalate (PET) and 4′-hydroxy-biphenyl-4-carboxylic acid (HBCA) was obtained by melt polycondensation of bis(2-hydroxyethyl) terephthalate and 4′-acetoxybiphenyl-4-carboxylic acid (ABCA) as co-monomers with Sb₂O₃ as a catalyst. Using this synthetic procedure, a set of copolymers containing 20–80 mol% of HBCA units was prepared. According to NMR spectroscopy, the copolymers were of random composition. Copolyesters comprising 60–80 mol% of HBCA possessed increased heat resistance and formed nematic melts at 270 °C and higher. The liquid crystal (LC) phase formation was accompanied by transition to non-Newtonian characteristics of the melt flow, as well as an equalization of storage and loss moduli values. According to XRD and polarizing microscopy, the LC glassy phase of the copolyesters coexists with crystalline regions of poly-(4′-hydroxy-4-biphenylcarboxylate), non-melting up to 400 °C and above. The mechanical characteristics of these LC copolyesters showed similar or better values than those of well-known LC polymers. These novel copolyesters can be useful in obtaining heat-resistant materials with an ordered structure and, as a consequence, improved performance.