Development of intelligent piezochromic materials based on spin crossover complexes

Details

Supervisors

Garcia, Yann

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

This master thesis demonstrates the piezochromic capabilities of a new type of polyurethane-spin crossover compound hybrid material for coating applications, as well as its superiority over currently researched piezochromic compounds. Two spin crossover compounds, [Fe(NH2trz)3]Br2∙nH2O and Fe(pyrazine)[Fe(CN)5NO] displayed degrees of compatibility with regular as well as UV-cured waterborne polyurethane matrices, with piezochromic and/or thermochromic properties for different ranges of temperature. The piezochromic response of this hybrid material presented a mappable relationship with the pressure applied, which allowed for the development of impact detection and pressure determination models. For impact detection, an ensemble of multiple typical machine learning algorithms provided the best results. For pressure determination, “random forest” and polynomial models were found to be optimal. This same hybrid material was then modified to provide both piezo- and thermofluorescent responses as well, by coupling the spin crossover phenomenon with the fluorescence intensity of well-known fluorophores from the fluorescein and rhodamin families.