Prior to the sonication of the shell composite and octadecane mixture, the mixture contained a broad range of particle sizes with a span of 170 µm and mean size of 0.117 µm as determined by laser diffraction experiments (Figure ). The graphene oxide and carbon nanotubes are attributed to the smaller sized particles (~50 nm), and the octadecane making up the larger particles (~1, 4, 11 and 30 µm). After the sonication process, the multimodal distribution was replaced with a unimodal curve, indicative of a uniform emulsion. The mean average size of emulsion droplets was recorded as 2.35 µm with a reduced span of 1.91 µm (Figure ). From DSC measurements of the freeze-dried capsules (Figure ) the encapsulated PCM had a melting point of 26.1 ± 0.025 °C and enthalpy of 217 ± 0.09 J•g -1 . This demonstrates an encapsulation efficiency of 98% which is comparable to the 96% efficiency reported previously for the same synthesis process. The melting curve of the capsules is broader than the melting curve of the bulk octadecane which is indicative of the various size of capsules. Furthermore, the crystallisation curve of the capsules has lost the 'kinetic loop' observed in the bulk upon recrystallization as nucleation now occurs on the inside of the shell. The capsules also provided some protection from thermal decomposition, TGA of the capsules and the bulk showed that there was a delay in the onset of thermal decomposition (Figure ).