Microencapsulation of 1-hexadecanol as a phase change material with reversible thermochromic properties

Herein, a novel approach for generating a microencapsulated reversible thermochromic phase change material (RTPCM) is described. The system described uses a spirolactone derivative color former, phenolic hydroxyl compound color developer, and 1-hexadecanol as the phase change material and co-solvent. The microencapsulation is achieved by complex coacervation of modified gelatin containing vinyl groups and gum arabic. This is followed by the crosslinking reaction between vinyl groups on modified gelatin and a divinyl crosslinker and subsequent crosslinking reaction with glutaraldehyde to improve stability and encapsulation efficiency. The influence of various key parameters on properties of the microcapsules (encapsulation efficiency, morphology, and particle size) are reviewed including the substitution degree of vinyl groups on modified gelatin, the type and amount of divinyl crosslinkers, and the core/shell ratio. Thermal properties and reversible color reliability of the generated microcapsules were found to be stable after 100 thermal heating and cooling cycles. Such microcapsules are well suited for latent heat storage and as an indicator for the states of energy saturation and consumption in phase change material applications directly through color change.