Vol 65, No 2 (2023)

Environmentally friendly method for the synthesis of crosslinked poly(siloxane-urethanes) avoiding the use of toxic isocyanates has been presented. The synthesis has been performed in two stages: at the first stage, non-isocyanate poly(siloxane-urethanes) have been synthesized via aminolysis of cyclocarbonates (differing in the structure and functionality) with oligomer dimethylsiloxanes bearing aminopropyl and ethoxy substituents, and crosslinked non-isocyanate poly(siloxane-urethanes) have been obtained via hydrolysis of the ethoxy groups with air moisture. According to the TGA data, processes of thermooxidative decomposition of the non-isocyanate poly(siloxane-urethanes) begin at 240‒260°C, depending on the structure of the organic block. Structural organization of the films has been investigated and glass transition temperature of two blocks (flexible siloxane and rigid urethane ones) has been determined by means of DSC and TMA. Surface of the film samples of non-isocyanate poly(siloxane-urethanes) has been assessed by means of scanning electron microscopy.

The interaction of phenylboronic acid with polyphenylsiloxane and a hydroxy(phenyl)siloxane oligomer has been studied. For the first time, phenylboronic acid was used as a starting material for the production of polyboronphenylsiloxanes under conditions of mechanochemical activation. It has been established that the main side processes induced by activation are abstraction of the phenyl substituent from the boron atom, formation of biphenyl, and trimerization of phenylboronic acid. Since boron compounds (including phenylboronic acid) have biological activity, their introduction into the polymer chain will make it possible to obtain materials with useful properties. For example, boron-containing polymers can be used as coatings to protect against insect vectors of various diseases. The work is fundamental in nature and contributes to revealing and understanding the mechanisms of mechanochemical modification of organosilicon polymers.

Three monosilicon-substituted norbornene monomers with phenyl and siloxane groups at the silicon atom are synthesized by the one-step hydrosilylation of 2,5-norbornadiene. The proposed method allows the synthesis of monomers with a higher content of polymerization-reactive exo-isomer in products compared with similar adducts formed by the Diels‒Аlder reaction. The synthesized monomers show high reactivity in both metathesis polymerization and addition polymerization more sensitive to the substituent volume. Using these monomers two series of high molecular weight silicon-substituted polynorbornenes are prepared which are found to be glassy and thermally stable polymers.

A synthetic scheme allowing the preparation of nanostructured organosilicon luminophores of branched or dendritic structure with up to 18 bithiophenesilane donor fragments and one central acceptor fragment has been elaborated. This universal scheme has been successfully upscaled to 20 g of the product, and its efficiency has been verified by the synthesis of two earlier unknown bithiophenesilane dendrimers with dense molecular shell and the central acceptor fragment, 1,4-bis(5-phenylthienyl-2-yl)benzene. The synthesis of more branched dendrimers under the Suzuki reaction conditions has led to the formation of the side products with the rupture of the Si–C(thiophene) bond, not typical of the synthesis of analogous compounds with lower branching degree under the same conditions.

This review analyzes the areas of practical application of oligomeric and polymeric organometal siloxanes as reduced fire risk coatings, antifriction and heat-resistant coatings, materials with high refractive index, and protective coatings for space equipment as well as functional branched oligomers as the most universal organometal siloxane synthons for diverse use.