Sol gel process

Table of Contents • • • • • • Sol gel methods are based on the principle of transition of materials from the solution or sol phase to the gelatinous or gel phase. It is a process of oxide network formation via polycondensation reaction in the solution phase. Sol–gel process, one of the Sol-gel method of preparation of nanomaterials In sol-gel method, hydrolysis of reactive metal precursors occurs, followed by condensation and polymerization reactions. In general, when a liquid alkoxide, water, a co-solvent, and an acid or base as a catalyst are combined, M-O-M crosslinks (oxo-bridges) are created by removing an alkoxide’s alkyl groups. These crosslinks then condense to create a three-dimensional solid-phase network. Initially, metal oxides such as methoxides (M-OCH 3) and ethoxide (M-OC 2H 5) undergo hydrolysis where the alkoxy group OR is replaced by hydroxo ligands (OH). This step is called ligand exchange or hydrolysis. M(OR)n + H 2O → M(OH)(OR) n–1 + ROH where R is an alkyl group, C nH 2n+1. The reaction mechanism of this step involves the addition of a negatively charged HO δ– group to the positively charged metal center (M δ+), followed by the elimination of R-OH. Some of the factors like nature of the solvent, nature of the alkyl group, concentration of each species in the solvent, temperature, water to alkoxide molar ratio, and presence of acid or base as catalyst affect hydrolysis reactions. Following condensation, either alcohol or water is eliminated to produce ...

• Presents a general, accessible resource for students and professionals seeking an introduction to sol-gel science and applications • Covers current and emerging processes in cutting-edge sol-gel applications such as Ceramics, Catalysis, Chromatography, biomaterials, glass, and optics • Combines timeless principles with modern technological advances and new applications that have emerged since publication of the prior edition This book presents a broad, general introduction to the processing of Sol-Gel technologies. This updated volume serves as a general handbook for researchers and students entering the field. This new edition provides updates in fields that have undergone rapid developments, such asCeramics, Catalysis, Chromatropgraphy, biomaterials, glass science, and optics. It provides a simple, compact resource that can also be used in graduate-level materials science courses. • Book Title : Introduction to Sol-Gel Processing • Authors : Alain C. Pierre • DOI : https://doi.org/10.1007/978-3-030-38144-8 • Publisher : Springer Cham • eBook Packages : , • Copyright Information : Springer Nature Switzerland AG 2020 • Hardcover ISBN : 978-3-030-38143-1 Published: 11 March 2020 • Softcover ISBN : 978-3-030-38146-2 Published: 11 March 2021 • eBook ISBN : 978-3-030-38144-8 Published: 10 March 2020 • Edition Number : 2 • Number of Pages : XXV, 701 • Number of Illustrations : 48 b/w illustrations, 371 illustrations in colour • Topics : , ,

In this chemical procedure, a " Removal of the remaining liquid (solvent) phase requires a drying process, which is typically accompanied by a significant amount of Afterwards, a thermal treatment, or firing process, is often necessary in order to favor further polycondensation and enhance mechanical properties and structural stability via final The The interest in sol–gel processing can be traced back in the mid-1800s with the observation that the hydrolysis of 2 in the form of fibers and monoliths. Sol–gel research grew to be so important that in the 1990s more than 35,000 papers were published worldwide on the process. Particles and polymers [ ] The sol–gel process is a wet-chemical technique used for the fabrication of both glassy and ceramic materials. In this process, the sol (or solution) evolves gradually towards the formation of a gel-like network containing both a liquid phase and a solid phase. Typical precursors are metal alkoxides and metal chlorides, which undergo hydrolysis and polycondensation reactions to form a colloid. The basic structure or morphology of the solid phase can range anywhere from discrete colloidal particles to continuous chain-like polymer networks. The term −10m) to a few −6m). • Under certain chemical conditions (typically in base-catalyzed sols), the particles may grow to sufficient size to become colloids, which are affected both by sedimentation and forces of gravity. Stabilized suspensions of such sub-micrometre spherical particles ...