Аннотация:A number of novel polysiloxanes with grafted dialkyl-substituted [1]benzothieno[3,2-b][1]benzothiophene groups is synthesized by the hydrosilylation of polymethylsiloxane matrices with varying ratio of functional methylsiloxane and nonfunctional dimethylsiloxane fragments (1 : 5, 1 : 1, and 1 : 0) by reactive 2‑undecenyl-7-hexyl-[1]benzothieno[3,2-b][1]benzothiophene. The obtained comb-shaped polymers have a number-average molecular weight of (6–43) × 103 and a dispersity of 1.55–2.79. Study of the thermal and thermo-oxidative properties shows that the polymer, in which each second monomer unit contains [1]benzothieno[3,2-b][1]benzothiophene substituents, has the highest thermo-oxidative stability (413°С) and the smallest char residue at 700°С (3%). The lowest thermal stability is exhibited by the comb-shaped polymer with the 100% content of [1]benzothieno[3,2-b][1]benzothiophene fragments and the highest molecular weight for which a 5% weight loss starts at 274°С. The DSC study of the phase behavior of the synthesized polymers indicates that increase in the fraction of [1]benzothieno[3,2-b][1]benzothiophene fragments in monomer units and their molecular weight contributes to a rise in phase transition temperatures and reduction in their enthalpy compared with the monomer and the siloxane dimer of [1]benzothieno[3,2-b][1]benzothiophene. Introduction of 50 and 100% of [1]benzothieno[3,2-b][1]benzothiophene fragments into the siloxane polymer chain leads to the formation of liquid-crystalline mesophases with the enthalpy of transitions typical of smectics, as evidenced by polarizing microscopy and X-ray diffraction. For the polymers with the varied content of [1]benzothieno[3,2-b][1]benzothiophene fragments the values of the interlayer spacing in the smectic mesophase are determined, and their phase behavior is investigated. Effect of molecular weight on the packing of [1]benzothieno[3,2-b][1]benzothiophene is ascertained, and models for the interpenetration of side substituents in the obtained polymers are constructed.
