Measurement of glass-transition temperature of thermoreversible photochromic materials based on mechanochemical amorphization. (February 2021) - Tsujioka, Tsuyoshi
Abstract: Photochromic diarylethene (DAE) materials are expected to be applied to various organic devices, and it is important to measure the glass transition temperature ( T g ) in order to evaluate their stability. Although DAEs have excellent thermal stability, their colored state has a high melting point, and either a thermal cyclo-reversion reaction or decomposition occurs during the differential scanning calorimetry (DSC) measurement. T g s in the colored state, therefore, are hard to measure. In this study, we succeeded in measuring T g s of the colored state with DSC by preparing the colored amorphous state based on a mechanochemical effect for various DAEs. In addition, the relationship between the isomerization ratio and T g was determined by combining the amorphization and the thermal reversion reaction near the melting point. It was found that T g changed monotonically according to the isomerization ratio. Graphical abstract: Image 1 Highlights: We proposed a method for measuring the glass transition temperature of thermoreversible photochromic materials. The glass transition temperature of colored amorphous state was measured by differential scanning calorimetry. This amorphization is based on the mechanochemical effect. The glass transition temperature changed monotonically depending on a ratio of the colored and colorless molecules.