Photochromic Activity of Osmosil Hybrid Films with Phosphotungstate

• Grant number: 07/08238-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2008
• End date: December 31, 2009
• Field of knowledge: Physical Sciences and Mathematics - Chemistry
• Principal Investigator: Ubirajara Pereira Rodrigues Filho
• Grantee: Renata Brandão Brito
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

The aim of this project is to study the relationship between the photochromic activity and the formulation of ormosil hybrid films of silica and phosphotungstic acid. The undergaduate student is going to prepare these films by the sol-gel procedure and verify the effect of the apolar silane, for instance the phenyltriethoxysilane, on transparency, colour and photochromic response of the ormosil films. The photochromic parameters to be evaluated are wavelength, percent variation of the absorbance on continuous UV irradiation, response time, saturation time, reversibility and bleaching time. Beside these parameters, it will be characterized the inner-pore polarity by electronic spectroscopy using the Reichardt's dye probe and the adhesion on glassy, paper and polymeric substrates as a function of the surface energy as estimated using the sessile drop method.