STRUCTURE AND BIREFRINGENCE PROPERTIES OF SiO2-THIOPHENES XEROGELS SYNTHESIZED BY SOL-GEL-TEMPLATE

Abstract

The ceramic tubular substrates of SiO2-thiophenes as a ceramic membrane were prepared successfully by the combining method of sol-gel-template process. The organic precursor of 2,5-bis(trimethoxysilyl) terthiophene was used as a template agent and tetraethoxysilance (TEOS) was used as organic or inorganic silicon source. The gel formations of alkoxides are taken by condensation and polymerization of TEOS with the catalyst ammonium fluoride, after mixing with the precursor. Characterizations were taken by NMR solid, SEM and XR-powder diffraction. The result showed that surface morphologies of its membranes are defect-free, and the bond-linking structure has been formed between silicate and template agent. The (Si02) membrane prepared from TEOS has amorphous phase. The studies reveal that the silicone is mainly in tetrahedral coordination and combining with terthiophene units as a nanostructure to form lamellar struture. The optical birefringence properties of Si02-thiophenes hybrid aerogels in the visible range strongly depend on amount of organic unit's modifier. The higher transparency is observed for aerogels having higher content of alkoxysilane (TEOS) and than for the higher birefringence,normally observed for aerogels containing higher quantity of thiophenes units.