Synthesis of B-silylmethyl substituted o- and m-carboranes

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Synthesis and fungicidal properties of new bisphenol-containing oligoorganosiloxanes

New fungicidal and antimicrobial siloxane oligomers were prepared on the basis of γ-aminopropyltriethoxysilane and a series of bisphenols. Chemical immobilization of these oligomers on the surface of various fabrics was studied with the aim to develop textile materials resistant to microbiological degradation.     

First observation of a columnar mesophase in a carborane‐containing main‐chain semiflexible copolymer

A comparison of the structure and phase composition of a recently synthesized carborane‐containing copolymer and its wholly organic analogue was carried out by DSC and X‐ray analysis in a wide temperature range between 20–300°C. It is found that the incorporation of 10 mol‐% of m‐carboranedicarboxylic units in the polymer prepared from 4,4′‐dihydroxybiphenyl and sebacic acid, acting as mesogen and flexible spacer, respectively, leads to the formation of a columnar mesophase at elevated temperatures. This newly observed phase occurs in addition to the crystalline and liquid crystalline smectic phases known for the wholly organic analogue.     

Amphiphilic Linear-Branched Copolylactides and Disperse Systems on Their Basis

The linear-branched copolylactides containing linear side poly(ethylene oxide) blocks are synthesized and characterized. The critical micelle concentrations and the aggregative stability and the dispersity of oil/water emulsions stabilized by these copolymers are estimated. The polylactide microparticles are obtained by emulsification followed by evaporation of an organic solvent using acetylsalicylic acid as a model drug. The structure of copolylactides strongly affects the properties of the microparticles. On one hand, the presence of large poly(ethylene oxide) blocks in the linear-branched macromolecules leads to the formation of colloidal systems with a higher aggregative stability of emulsions and a lower size of particles, and on the other hand, the microparticles formed from these copolymers possess a lower incorporation efficiency relative to water-soluble low-molecular-mass compounds and the profile of the release of these compounds is nonlinear and contains the region of accelerated release.     

The influence of the molecular structure of polymers on their reactivity in polycondensation

The influence of the conditions of synthesis, the chain length and the chemical structure of macromolecules on their reactivity is examined. The main emphasis is placed on the connection between polymer molecular structure and macromolecular effects in polycondensation. The far order effect is presented as the principal chemical factor determining the reactivity of macromolecules in solution polycondensation reactions.     

Synthesis of poly(arylate-siloxane)s in supercritical carbon dioxide

The reaction between poly(4,4′-isopropylidene-2,2′-diphenylene (tere)isophthalate) copolymer and 3-aminopropyltriethoxysilane was investigated in supercritical carbon dioxide at 150 atm and 100° C. It was found that ester bonds in the copolyarylate undergo aminolysis under the above conditions to give rise to the formation of siloxane-containing amides, whose interaction with phenol groups of the macromolecules and moisture affords an insoluble poly(arylate-co-siloxane) fraction. Under the action of moisture, three-dimensional structures containing polyarylate and polysiloxane fragments are formed in the soluble fraction of the copolymer via the combined hydrolysis of ethoxysilane groups. The formation of the siloxane network affects the properties of the polymers. In particular, thermomechanical and thermal tests showed that sample deformation at 250°C decreases from 80 to 15%, while the carbon residue at 725°C increases twofold as compared to that of an initial polyarylate sample.     

Interchain exchange and interdiffusion in blends of poly(ethylene terephthalate) and poly(ethylene naphthalate)

The interchain exchange and interdiffusion in blends of poly(ethylene terephthalate) and poly(ethylene naphthalene-2,6-dicarboxylate) are investigated with reprecipitated commercial samples (M _η ～ 10⁴) and samples containing no polycondensation catalyst (M _η ～ 10³) synthesized in the course of this study. The kinetics of multiblock copolymer formation and gradual reduction of the mean block length in quasi-homogeneous blends were shown to fit a simple theoretical model of a second-order reaction. The increase of the reaction-rate constants on the transition from commercial samples to synthesized ones revealed a significant role of chain ends in interchain exchange. The detected activation energy of the interchange in the absence of catalysts (97 kJ/mol) was noticeably less than that previously reported for the polymer pair under study (120–170 kJ/mol). The obtained data were applied for analysing the interdiffusion between melts of the same polymers accompanied by the interchain exchange. By means of the microinterference method, the interdiffusion in the synthesized samples was shown to be much faster than that in the reprecipitated commercial samples, a result that may be due to the better compatibility of the initial polyesters as their molecular mass decreased. In later stages of the process in both systems, the interpenetration of components was slower than that predicted by Fick’s law, owing to formation of copolymer species that diminished the thermodynamical factor of mixing.     

Synthesis and photophysical properties of polyphenylquinoxalines with thiophene and dibenzothiophene units in the backbone

New bis(α-diketones) containing thiophene and dibenzothiophene groups were synthesized. Via the reaction of these monomers with aromatic tetramines under high-temperature polycondensation conditions, a series of new polyphenylquinoxalines combining high thermal and mechanical characteristics with solubility in organic solvents were prepared. Polyphenylquinoxalines exhibit intense fluorescence in solution and in thin films with maxima in the region of 432–522 and 450–530 nm in the case of thiophene-containing and dibenzothiophene derivatives, respectively.     

Surfactant properties of hydroxyethylated fats

Surfactant properties of hydroxyethylated fats were studied.