Visual detection of topology freezing transition temperature of vitrimers based on fluorescein-soaked coatings from photonic crystals and vitrimers

Abstract

Topology freezing transition temperature (Tv) of vitrimers is a key parameter for their applications. Common detection methods of Tv are used by the rheology and dynamic mechanical analyzer under external forces, but the external forces may affect Tv. Herein, a visual detection method of Tv is proposed based on the fluorescein-soaked photonic coatings from the lower photonic crystals (PCs) and the upper vitrimers. Because PCs have photonic band gaps (or structural colors), and by combining different structural colors of PCs and fluorescence of vitrimers soaked with fluorescein, when the heating temperature is higher than Tv of vitrimer, ester (or carboxyl) of fluorescein has ester exchange for the ester group in vitrimers, color and fluorescence intensity of photonic coatings have great changes. Tv of vitrimers is easily obtained according to these obvious changes and it is unaffected from different fluorescein. And accurate fluorescence spectra would be measured to further identify the Tv value of vitrimers. The lower PCs enhance the sensitivity of Tv detection of vitrimers. The visual detection method is simple, non-damage, accurate, good reliability, universality and without expensive equipment.