Proceso Sol-Gel en la Síntesis de Dióxido de Silicio (Sio2)

En ciencia de los materiales el dióxido de silicio, también conocido como sílice, ha recibido significante atención en diferentes áreas de investigación, ganando un espacio importante y de mucho interés entre los investigadores, debido a sus diversas aplicaciones que abarcan desde la síntesis de soportes para catalizadores hasta materiales para la liberación controlada de fármacos. Es motivo por el cual, en este manuscrito se dan a conocer aspectos químicos fundamentales e importantes sobre el proceso sol-gel en la síntesis de la sílice a partir de moléculas precursoras de alcóxidos de silicio y organosilanos. Se analiza cómo el catalizador ácido/básico y el tipo de precursor afectan a las reacciones de hidrólisis y condensación, así como a la estructura y morfología del material. Palabra clave: Sílice, Sol-gel, Hidrólisis, Condensación, Alcóxido. Abstract In materials science, silicon dioxide has received significant attention in different research areas, gaining valuable space and interest between researchers due to its diverse applications, ranging from the synthesis of supports for catalysts to materials for controlled drug liberation. Herein we describe fundamental and important chemical aspects of the sol-gel process in the synthesis of silica, starting from precursor molecules of silicon alkoxides and organosilanes. Moreover, this review analyses how the acid/basic catalyst and the type of precursor affect the hydrolysis and condensation reaction, as well as the structure and morphology of the obtained material. Keywords: Silica, Sol-gel, Hydrolysis, Condensation, Alkoxide.

Hydrophobic silica-aerogel integrated polyacrylonitrile nanofibers

Owing to its high specific surface area, high thermal stability and excellent thermal insulation, silica aerogel is used as an insulating material in protective clothing. In this study, the hydrophobicity and thermal insulation properties of the electrospun polyacrylonitrile (PAN) nanofibers were enhanced by integrating silica aerogel (SA), which was synthesized using silicic acid as silica precursor instead of silicon alkoxides or sodium silicate and modified with phenyltrimethoxysilane. The electrospun PAN-SA composite nanofibers showed higher surface roughness and hydrophobicity (water contact angle of 142°) compared to the smooth and hydrophilic PAN (control) nanofiber. Further, the thermal stability of the PAN nanofibers was increased by 17 °C while their thermal conductivity was decreased from 15.8 W/mK to 0.4 W/mK (reduction of 97.5%). These features make the PAN-SA composite nanofibers particularly suitable for use in thermal insulation protective clothing.

Mesoporous Materials: From Synthesis to Applications

Mesoporous silica are inorganic materials, which are formed by the condensation of sodium silicate or silicon alkoxides around an ordered surfactant used as template [...]