Vacuum evaporative deposition of photochromic spirophenanthroxazine thin films and their solvato-bleaching feature

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Volume Title

Kemian tekniikan korkeakoulu | Master's thesis

Date

2019-08-20

Department

Major/Subject

Functional Materials

Mcode

CHEM3025

Degree programme

Master's Programme in Chemical, Biochemical and Materials Engineering

Language

en

Pages

59+5

Series

Abstract

Stimuli-responsive materials are the major contributors to functional materials that play a significant role in many fields such as sensors and actuators. Among these materials photochromic molecules has attracted both the scientific and industrial communities, due to their unique features. When exposed to UV radiation photochromic materials would either exhibit isomerization (e.g. trans-cis / cis-trans), or result in a ring opening /closure, which would result not only in a change in their absorption spectrum, but also in their chemical and physical properties such as refractive indices, dielectric constants, oxidation-reduction potentials and geometrical structures. The embedment of photochromic molecules particularly Spirooxazine within a polymer matrix has been studied significantly in literature, yet due to its synthesis limitations standalone systems including the transform from particle, percolated and continuous film where never reported to the best of our knowledge. Thus, herein we introduced the deposition of standalone Spirooxazine thin films via evaporative deposition with emphasizing the percolated and continuous film samples. The cluster deposition of SPO is being extensively studied elsewhere by our group under the framework of ASCI project. The deposited films were studied for their chemical integrity, thickness, crystallinity, density, and photochromic ability. In addition, the deposited films decay kinetics were studied under both constant temperature and the influence of multiple volatile organic compounds (VOCs) such as Acetone, Acetonitrile and Isopropanol. Where a new unreported term, Solvato-bleaching, was assigned to describe the color fading kinetics upon VOCs exposure. It was determined that the solvato-bleaching rate of the deposited film is dependent on the polarity of the solvent, so that with decreasing polarity the rate increases. However, some exceptions may take place when the surface morphology changes, thus we assume that the interaction is a surface limited reaction.

Description

Supervisor

Elbahri, Mady

Thesis advisor

Soliman, Ahmed
Yetik, Mehmet

Keywords

physical vapor deposition, photochromic molecules, cluster and percolation, solvato-bleaching

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