1 research outputs found
Origin of the Reversible Thermochromic Properties of Polydiacetylenes Revealed by Ultrafast Spectroscopy
Polydiacetylenes
(PDAs) with thermochromic properties undergo colorimetric
transitions when the external temperature is varied. This capability
has the potential to enable these materials to be used as temperature
sensors. These thermochromic properties of PDAs stem from their temperature-dependent
optical properties. In this work, we studied the temperature-dependent
optical properties of Bis-PDA-Ph, which exhibits reversible thermochromic
properties, and PCDA–PDA, which exhibits irreversible thermochromic
properties, by UV–visible absorption and femtosecond transient
absorption spectroscopy. Our results indicate that the electronic
relaxation of PDAs occurs via an intermediate state in cases where
the material exhibits reversible thermochromic properties, whereas
the excited PDAs relax directly back to the ground state when irreversible
thermochromic properties are observed. The existence of this intermediate
state in the electronic relaxation of PDAs thus plays an important
role in determining their thermochromic properties. These results
are very important for both understanding and strategically modulating
the thermochromic properties of PDAs