Surfactant Selection in Phase Change Dispersions

摘要

In this work, the thermophysical behaviour of dispersions formulated with different surfactant systems ispresented. Firstly, a surfactant was chosen on accounts of its bulky substituent groups and the thermophysicalproperties were compared to the results from a standard surfactant system. Thermal analysis showed thesupercooling degree to be 13 K with the standard surfactant system, and 4 K with the bulky surfactant,suggesting the surfactant had nucleating-inducing behaviour. However, the bulky surfactant resulted in aviscous phase change dispersion, which separated after thermal cycling. Consequently, smaller co-surfactantswere added to allow higher packing densities to increase stability, and decrease the viscosity, whilst keepingthe nucleating ability of the original surfactant. This optimised surfactant system showed a supercoolingreduction of 9 K and thermal stability during extended cycling. Overall, the results demonstrate an innovativeapproach in fine-tuning the thermophysical properties of a phase change dispersion with the use of cosurfactants.