Alkane Grafted Phase Change Azobenzene Materials Based on Low Temperature Heat Release

Alkyl-grafted phase change azobenzenes,4-pentyl-azobenzene(Azo5) and 2'-methyl-4- n-pentylazoben. zene(AzoM5),with two different substituents were synthesized by the Mills method. The chemical structures of Azo5 and AzoM5 were characterized by nuclear magnetic resonance hydrogen spectroscopy and Fourier transform infrared spectroscopy. The isomerization performance,cycling stability,thermal storage,exothermic properties and the abili. ty to release heat at. 10. of the materials were analyzed by ultraviolet-visible spectroscopy,differential scanning calorimetry and infrared thermography. The results show that Azo5 and AzoM5 exhibit low melting point and rapid isomerization transformation due to the low intermolecular force. And due to the photo-induced phase change at low temperature,the energy density increases significantly,reaching 216 and 218 J/g,respectively. Infrared thermography shows that Azo5 can achieve a temperature increase of 6 degrees C at low temperatures(-10 degrees C)under visible light irradiation.