Silica based photonic crystals embedded in a chitosan TEOS matrix: preparation, properties and proposed applications
Our research involves the development of a pH sensitive chitosan tetraethyl orthosilicate interpenetrating polymer network (Chi TEOS IPN) suitable for the introduction of ordered silica nanoparticles. The pH sensitive properties of the IPN provide an innovative framework for ordered colloidal silica (SiO2) films known as photonic crystals. The pH sensitive properties of chitosan occur naturally due to its cationic polyelectrolyte structure; cross linking with TEOS provides mechanical strength and incorporation of the silica photonic crystal provides a means of optical detection for a pH driven expansion mechanism. Chitosan tetraethyl orthosilicate silica (Chi TEOS SiO2) composites are formed through a three step mechanism in which the silica photonic crystal and Chi TEOS IPN hydrogel are synthesized separately and then combined to form the Chi TEOS SiO2 composite. The silica photonic crystals, IPN membranes and final composite structures were analysed separately through optical, mechanical and swelling studies. Through the successful fabrication of a Chi TEOS SiO2 composite we propose a membrane suitable for applications in environmental, chemical and biological sensing of pH.
Journal of Materials Science