Polymer with Variable Thermal Conductivity Regulated by Photoirradiation

The signal-to-noise ratio (SNR) of on-orbit ultraviolet(UV) imagingspectrometers (UVIS) can be significantly impacted by variations inheat flows. To improve SNR, it is necessary to develop intelligentmaterials with variable thermal conductivity to optimize the thermalenvironment. In this study, we synthesized an intelligent materialcalled poly-6-(4-(phenyldiazenyl)phenoxy)hexyl methacrylate (Habpolymer),which contains photosensitive cis-trans isomeric groups, usinga nontoxic and convenient photopolymerization method. Under green(525 nm) and UV (365 nm) photoirradiation, Habpolymer was observedto exist in trans-Habpolymer and cis-Habpolymer states, respectively. Interestingly, the thermal conductivityof Habpolymer reversibly switched between 0.35 & PLUSMN; 0.03 (cis-Habpolymer) and 0.78 & PLUSMN; 0.10 W m(-1) K-1 (trans-Habpolymer). The highthermal conductivity state of trans-Habpolymer wasfound to be 122.9% higher than that of cis-Habpolymer.Furthermore, the photosensitive Habpolymer demonstrated a remarkableability to rapidly switch its thermal conductivity through photoirradiation,achieving a transition time of just 10 s. This was significantly quickerthan the transition times achieved by other methods such as electrochemicalmodulation and magnetic field molecular orientation, which were dozensof times slower. Based on theoretical mechanisms, the photosensitivecis-trans isomer groups of Habpolymer can induce differentspatial configurations of macromolecules, which in turn can changethe thermophysical properties of their phonon transport under photoirradiation.In conclusion, our results demonstrate that Habpolymer has great potentialfor use in thermal control technology for UVIS.