pH effects on sol-gel synthesis

The sol-gel synthesis can be obtained from metallo-organic compounds using alkoxides as precursors. Alkoxides with a M(OR)n structure, where M is a metal or a metalloid and R is an alkyl group (R = CH3, C2H5, …). Such chemicals are dispersed in a solvent (usually organic, ethyl alcohol) and react in an pH controlled medium. In this post,… Continue reading pH effects on sol-gel synthesis

Hydrophobic coatings I

Hydrophobicity phenomena are present in nature; in the leaves of plants such as Nelumbo nucifera (lotus), in the wings of butterflies, or in the legs of water striders. It is also a leading surface property for corrosion protection, as hydrophobic surfaces are water and aqueous electrolytes repellant, anti-icing, bio-corrosion and anti-fouling [1]. These properties can… Continue reading Hydrophobic coatings I

Sol-gel and architecture I: anti-reflective coatings

The use of light building envelopes, made of materials such as steel and glass, has progressively substituted the traditional concrete and brick structures. This change poses new design challenges in order to control parameters such as the solar factor, the thermal transmittance, visual transmittance, reflection index, among others [1]. The thermal and energetic efficiency of… Continue reading Sol-gel and architecture I: anti-reflective coatings

The Layer-by-Layer (LbL) assembly

The Layer-by-Layer (LbL) assembly, also called Electrostatic Self Assembly Multilayer (ESAM), consists of the immersion of the substrate into alternate solutions with opposite electric charge [1]. This electrostatic attraction is the main force of adhesion to the surface of the substrate. It was discovered in 1966 although this technique went unnoticed until the nineties, when… Continue reading The Layer-by-Layer (LbL) assembly

Sol-gel coatings, a safe alternative to chrome plating

Since the beginning of the 20th century, hexavalent chromium derivates have been used to prevent corrosion and to improve the adherence of further coatings on zinc, magnesium, steel and aluminum alloys. Chromium (VI), or hexavalent chromium, is one of the most stable oxidation states of chromium. It very seldom occurs in nature and most hexavalent… Continue reading Sol-gel coatings, a safe alternative to chrome plating

Sol-gel biomedical applications: Hydroxyapatite, bone repair

Hydroxyapatite – Ca5(OH)(PO4)3–  is a complex phosphate of calcium that has chemical and structural resemblance to bone [1]. Thanks to these properties similar to bone and teeth, hydroxyapatite is commonly used for tissue repair. Hydroxyapatite has been widely used for bone defects reparation in dentistry and orthopedics, tooth replacement, alveolar ridges augmentation or and maxillofacial… Continue reading Sol-gel biomedical applications: Hydroxyapatite, bone repair