Glasses sol-gel

Recently, interesting composite materials incorporating polymeric materials into the sol-gel glasses have been reported by Wilkes and his co-workers [9]. These materials are named ceramers . The properties of ceramers strongly depend on the reaction conditions, i.e., acidity, water content, reaction temperature, the amount of organic polymer, the molecular weight of polymer, solvent, and so on. 

Reisfeld R, Jorgensen CK (1991) Optical Properties of Colorants or Luminescent Species in Sol-Gel Glasses. 77 207-256... 

New Hybrid Materials Incorporating Poly (tetramethylene oxide) into Tetraethoxysilane-Based Sol—Gel Glasses... 

Braun, S., Rappoport, S., Zusman, R., Avnir, D. and Ottolenghi, M. (1990) Biochemically active sol-gel glasses the trapping of enzymes. Materials Letters, 10, 1-5. 

Sol-gel glass as a new support matrix in immunoafBnity chromatography. Fresenius Journal of Analytical Chemistry, 352, 654—659. 

Fig. 12.14 Mechanical parameters calculated by nano-indenta-tion tests for a conventional sol—gel glass and two different bioactive star gels with analogous Ca/Si molar ratio.

Tab. 12.3 Fracture toughness (K c) values of a conventional sol-gel glass, star gels and those obtained for human cortical bone by different authors.

Vallet-Regi, M., Romero, A.M., Ragel, C.V. and LeGeros, R.Z. (1999) XRD, SEM-EDS, and FTIR studies of in vitro growth of an apatite-like layer on sol-gel glasses. Journal of Biomedical Materials Research, 44, 416-421. 

Arcos, D., Greenspan, D.C. and Vallet-Regi, M. (2002) Influence of the stabilization temperature on textural and structural features and ion release in Si02-Ca0-P20s sol-gel glasses. Chemistry of Materials, 14, 1515-1522. 

Salinas, A.J., Merino, J.M., Hijon, N., Martin, A.I. and Vallet-Regi, M. (2004) Bioactive organic-inorganic hybrids based on CaO-Si02 sol-gel glasses. Key Engineering Materials, 254-256, 481-484. 

Vallet-Regi, M., Salinas, A.J., Ramirez-Castellanos, J. and Gonzalez-Calbet, J. M. (2005) Nanostructure of bioactive sol-gel glasses and organic inorganic hybrids. Chemistry of Materials, 17, 1874-1879. 

MacCraith B.D., Ruddy V., Potter C., O Kelly B., McGilp J.F., Optical waveguide sensor using evanescent wave excitation of fluorescent dye in sol-gel glass. Electron. Lett. 1991 27 1247. 

Sol-gel glass is ion-permeable due to its residual hydroxy groups and its porosity, and can be used to optically measure pH by entrapping (caging) conventional pH indicator dyes in the material. Often, water soluble indicator dyes do not have to be chemically modified for immobilisation (see chapter 4) because, due to their size, they are retained in the pores of the sol-gel glass and are not washed out. 

Silica sol-gel glasses are porous materials, which means some kind of solid material that has holes in it. These holes are also called pores. To call a material a porous material, there is usually some kind of implicit assumption of homogenization and length scale. The holes must be smaller enough, compared to the typical size of the piece of material that is considered, so that it is reasonable to consider the material as a mixture of solid framework and pores28. 

---