Design and investigation of novel photoactive liquid crystalline organic-inorganic hybrids

Ferreira, Ana João Tavares

Abstract

This work describes and discusses the design, synthesis and characterization of novel photoactive liquid crystalline silsesquioxanes. The investigations carried out include the initial design, chemical synthesis and characterization, photochemical properties, liquid crystalline behaviour and optical properties.

The new materials were carefully designed in order to target the specific requirements of incorporating azobenzene moieties as photoactive groups and exhibiting liquid crystalline properties, specifically nematic mesophases and glassy states at room temperature. In order to achieve these properties four series of monodisperse inorganic/organic hybrids were synthesised. The liquid crystalline properties were tuned using a multiple-mesogen approach similar to the one used in polymeric systems. Tools used were variation of mesogen groups and the use of a combination of lateral and terminally connected mesogens. Chemical characterization of the materials was carried out and mesogen composition determined.

Photochromic behaviour was investigated followed by a study of the liquid crystalline properties using several techniques including OPM, DSC and XRD studies. The phase structure was determined by means of detailed temperature dependent XRD studies using both mechanically and magnetically aligned samples. New assembly modes such as lamellar nematic phases were proposed.

The optical properties were investigated by means of photoorientation and SRG studies in thin film samples which were carried out by me in collaboration with Jaroslaw Tomczyk and Professor Joachim Stumpe in the Fraunhofer Institute in Potsdam, Germany, during my visit as part of the MC-ITN-“Dendreamers” project.

Citation

Ferreira, A. J. T. (2013). Design and investigation of novel photoactive liquid crystalline organic-inorganic hybrids. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4215209

• Thesis Type: Thesis
• Deposit Date: Feb 19, 2014
• Publicly Available Date: Feb 23, 2023
• Keywords: Chemistry
• Public URL: https://hull-repository.worktribe.com/output/4215209
• Additional Information: Department of Chemistry, The University of Hull
• Award Date: May 1, 2013