Browsing by Author "Tsvetkova Y."

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    Sol - gel silica hybrid materials applicable for external treatment of concrete defects
    (2015-01-01) Todorova E.; Chernev G.; Djambazov S.; Tsvetkova Y.
    The sol-gel silica hybrids are materials with application in different fields - pharmacy, medicine, sensors, etc. Concrete self - healing is a new area of applications of this kind of materials. It is connected with filling the cracks and preventing their further destruction as well as providing materials able to form CaCO3 as filler. A combination of hybrid materials containing calcium ions and bacterial cells is the optimal choice for that purpose. The material should exhibit stability, durability and ability to penetrate in the cracks. Furthermore, it should be reactive and biocompatible in order to interact with bacterial cells and promote further formation of CaCO3. Hybrid materials based on silica network and in situ incorporated organic components (chitosan and polyethylene glycol) is synthesized by the sol - gel method. The silica matrix obtained from tetraethylorthosilicate provides the structure with stability and durability, while the organic components account for its flexibility, biocompatibility and reactivity. The results from the structural analysis (XRD, FTIR, SEM and AFM) show that hybrids thus obtained have an amorphous, homogeneous structure. Formation of the silica network and backbone organic units is observed by FTIR spectroscopy. The AFM surface micrographs show the presence of particles of a size from 50 nm to 1 μm. They serve as reactive centers for potential interactions with the bacterial cells. The results from the structural characterization show that the synthesized materials can be used as carriers for bacterial cells' immobilization and applied further as fillers for external treatment of concrete defects.