A Novel Thermally Conductive Phase Change Material of Polythiophene-Coated Core–Shell Polyethylene Glycol/Nano Zinc Oxide by In Situ Polymerization

Two kinds of thiophene monomers (thiophene and thiophene carboxylic acid) are used to synthesize a series of polythiophene matrix materials with different ratios. Polythiophene carboxylic acid can form strong hydrogen bonds between molecules, and the conjugated thiophene ring can be used to obtain higher thermal conductivity. The core–shell structure of polythiophene-coated polyethylene glycol and nano zinc oxide was synthesized by in situ polymerization to form a shaped phase change composite. The electron micrograph shows this phenomenon very well. Comparing the thermal conductivity and heat storage performance of two different polythiophene matrix composites, it can be explained that the chemical interaction between molecules is conducive to the formation of heat conduction pathways. Thermal decomposition temperature of polythiophene carboxylic acid and its polyethylene glycol composite structure is about 10 °C higher than that of polythiophene, which, on the other hand, also indicates the tight molecular arrangement. It is derived from the differentiation of its molecular structure, and this compact structure plays a positive role in the improvement of its thermal conductivity. However, excessive intermolecular force hinders the regular arrangement of polyethylene glycol. Under the condition that the amount of thermal conductive filler is 25%, the thermal conductivity is increased from 0.895 to 1.05 W · m–1k–1 and the phase transition is decreased from 149 J/g to less than 135 J/g. Finally, the stability of the shaped phase change composite was good, the solid form was maintained near the phase transition temperature, and no leakage was observed.