Star-Shaped Polydimethylsiloxanes with Organocyclotetrasilsesquioxane Branching-Out Centers: Synthesis and Properties

Abstract

New non-crystallizable low-dispersity star-shaped polydimethylsiloxanes (PDMS) containing stereoregular cis-tetra(organo)(dimethylsiloxy)cyclotetrasiloxanes containing methyl-, tolyl- and phenyl-substituents at silicon atoms and the mixture of four stereoisomers of tetra[phenyl(dimethylsiloxy)]cyclotetrasiloxane as the cores were synthesized. Their thermal and viscous properties were studied. All synthesized compounds were characterized by a complex of physicochemical analysis methods: nuclear magnetic resonance (NMR), FT-IR spectroscopy, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), viscometry in solution, rheometry, and Langmuir trough study.

Synthesis of Siloxane Derivatives of Phenylboronic Acids of Different Structures

“…Difunctionalized derivatives 5 and 6 can be used to prepare copolymers, where they can be included as soft and rigid blocks. Polyfunctionalized compounds 7–9 are of interest from the viewpoint of the preparation of various star-shaped polymers …”

“…Polyfunctionalized compounds 7−9 are of interest from the viewpoint of the preparation of various star-shaped polymers. 39 Boronic acids can form dynamic covalent bonds; therefore, we decided to check out the possibility of deprotecting modifier 3. 40 It was found that the reaction proceeds under mild conditions at room temperature in the presence of excess water (Scheme 3).…”

Sequential hydrothiolation–hydrosilylation: a route to the creation of new organosilicon compounds with preset structures

“…This class of compounds makes it possible to obtain various functional derivatives and materials that can find application in various fields of chemistry and materials science. 54–64…”

“…This class of compounds makes it possible to obtain various functional derivatives and materials that can find application in various fields of chemistry and materials science. [54][55][56][57][58][59][60][61][62][63][64] Thus, we chose stereoregular organocyclosilsesquioxane 20 as the starting compound (Fig. 6).…”

Carborane-containing stereoregular cyclic phenylsiloxanes: synthesis, structure and properties

“…The possibility of introducing reactive groups (-OH, -H, and vinyl) at the silicon atom into the molecules of such cyclosiloxanes affords star and ladder-like polymers, surfactants, photoactive compounds and many other unique structures based on them. [26][27][28][29][30][31][32] From a fundamental and practical viewpoint, the introduction of polyhedral carboranes into the structure of stereoregular macrocycles is of great interest. The synergy between the physicochemical properties of siloxane and carborane moieties will open the way to unique compounds with enhanced thermooxidative and radiative stability.…”