preparation of acid-based deep eutectic solvent as phase change material

Deep eutectic solvents (dess), due to easy preparation and cost-effectiveness and having common characteristics with phase change material (pcm), are suitable candidates for using a pcm. in this work, were combined choline chloride as a quaternary ammonium salt and phenylacetic acid and oxalic acid as carboxylic acids to prepare a new type of dess. the temperature history, density, and viscosity tests were performed to determine the properties of the dess compounds. the phase diagram of prepared dess was obtained. the cycling results showed the degree of supercooling of the dess was significantly lower. however, phase segregation has occurred remarkably.