Silicon dioxide, or silica, is the most abundant oxide compound on the earth’s crust. It commonly exists in nature as quartz, sand, sandstone, and flint. silica is used to produce ferrosilicon, glass, ceramic tiles, and many other industrial products. silica is found in nature in the form of crystalline or non-crystalline (amorphous silica) and as an uncombined form or in combination with other elements. Pure silica can be obtained using chemical synthesis methods. silica obtained from chemical synthesis methods has a non-crystalline structure and is known as Synthetic Amorphous Silica (SAS). Synthetic Amorphous Silica can be produced on a nanoscale or microscale. Silica-based nanoparticles received significant attention in research and industrial fields due to their facile synthesis procedures, colloidal stability, controllable particle size, ease of surface modification, facility of surface functionalization, and synthesis in various scales. silica nanoparticles can be produced as powder, colloid, and gel on an industrial scale.
History
Research by Graham in 1861 is considered the starting point for the industrial development of colloidal silica. Colloidal silica, which contains 10% SiO2 particles, became commercially available for the first time in 1933. Research by Graham in 1861 is considered the starting point for the industrial development of colloidal silica. Colloidal silica, which contains 10% SiO2 particles, became commercially available for the first time in 1933. In subsequent years, efforts were made to produce stable colloidal silica containing higher concentration of SiO2 particles. Finally, in 1956, a method for preparing stable colloidal silica containing 30% SiO2 particles with a diameter of less than 10 nm was introduced. In this way, silica nanoparticles were introduced in the middle of the 20th century for the first time.
Werner Stober is recognized as a pioneer in the synthesis of silica nanoparticles, having introduced the “Stober process” in 1968. silica nanoparticles synthesized using the Stober method are monodisperse, and their diameter can be controlled in the range of 20-2000 nm. Stober process is based on the sol-gel method and involves the reaction of a silica precursor such as tetraethyl orthosilicate in a solution of water and alcohol containing ammonia.
In 1983, Klaus Unger’s research group in Germany succeeded in synthesizing colloidal silica containing porous amorphous silica particles in micrometer dimensions and with non-uniform particle size. This group used porous silica particles as a carrier in targeted drug delivery and as a stabilizing agent.
In the past 50 years, scientists have synthesized various types of silica nanoparticles with different shapes, sizes, and hole structures.
