Polysilsesquioxanes Through Base-Catalyzed Redistribution of Oligohydridosiloxanes (original) (raw)

Poly(silsesquioxanes) derived from the hydrolytic condensation of organotrialkoxysilanes containing hydroxyl groups

Journal of Organometallic Chemistry, 2003

Organotrialkoxysilanes containing secondary hydroxyl groups were synthesized by reacting 1 mole of (3-aminopropyl)triethoxysilane (APS) with 1 or 2 mole of phenylglycidylether (PGE). Resulting products, APS–PGE and APS–PGE2, respectively, were subjected to hydrolytic condensation at 50 °C during 24 h. For APS–PGE, the reaction was performed using a molar ratio [H2O]/Si=3, without addition of an external catalyst. For APS–PGE2, the reaction was catalyzed by HCOOH or NaOH. Resulting poly(silsesquioxanes) (PSSO) were characterized by size exclusion chromatography, Fourier-transformed infrared spectroscopy and matrix-assisted ultraviolet laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS). PSSO derived from APS–PGE and APS–PGE2, catalyzed by HCOOH, exhibited a relatively narrow distribution of polyhedral structures. This constitutes a simple one-step synthesis of polyhedral oligomeric silsesquioxanes (POSS) functionalized with amine and/or hydroxyl groups. The directionality of the reaction pathway towards the formation of polyhedral structures was ascribed to the formation of intramolecular SiOC bonds through the reaction of SiOEt or SiOH groups with secondary hydroxyl groups. Intramolecular SiOC bonds were found in the structures of APS–PGE and APS–PGE2, and in most of the species of the PSSO obtained from the NaOH-catalyzed reaction of APS–PGE2. A small fraction of surviving SiOC bonds was also found in the polyhedral structures of the PSSO derived from the hydrolytic condensation of APS–PGE and APS–PGE2 catalyzed by formic acid. By usual organic reactions transforming hydroxyl groups into other functional groups, it is possible to generate narrow distribution of multi-functionalized POSS starting from an OH-functionalized organotrialkoxysilane.The hydrolytic condensation of organotrialkoxysilanes containing secondary hydroxyl groups led to a narrow distribution of OH-functionalized polyhedral oligomeric silsesquioxanes. The generation of closed structures was ascribed to the reversible formation of intramolecular cycles through SiOC bonds. Under appropriate conditions, structures containing these cycles were present in high concentrations.

Polysiloxanes Grafted with Mono(alkenyl)Silsesquioxanes—Particular Concept for Their Connection

Materials

Herein, a facile and efficient synthetic route to unique hybrid materials containing polysiloxanes and mono(alkyl)silsesquioxanes as their pendant modifiers (T8@PS) was demonstrated. The idea of this work was to apply the hydrosilylation reaction as a tool for the efficient and selective attachment of mono(alkenyl)substituted silsesquioxanes (differing in the alkenyl chain length, from -vinyl to -dec-9-enyl and types of inert groups iBu, Ph at the inorganic core) onto two polysiloxanes containing various amount of Si-H units. The synthetic protocol, determined and confirmed by FT-IR in situ and NMR analyses, was optimized to ensure complete Si-H consumption along with the avoidance of side-products. A series of 20 new compounds with high yields and complete β-addition selectivity was obtained and characterized by spectroscopic methods.

Nano-engineering and micromolecular science of polysilsesquioxane materials and their emerging applications

Journal of materials chemistry A, 2019

Polysilsesquioxanes (RSiO 1.5) n are organic-inorganic hybrid materials that have an array of properties and synergistic features and are considered to be robust materials in the family of siliceous compounds. Their careful tailoring at the nano and micro scale has been investigated worldwide, as their architecture dictates the final properties. Non-porous nano and micro organosilica hybrid particles that have been designed using careful optimization of the effective parameters, for example the amount of monomer, reaction time, concentration of the catalyst, temperature, and stirring speed, are detailed in this article. Different sized particles comprising bridged, ladder-like, cage shape and other geometries modified by organically functionalized reagents are discussed. This review presents a summary of the recently reported nano and micro-sized polysilsesquioxanes with different functional materials and their geometries, describing their preparation methods and further applications in science and technology, especially those reported in the last half decade.