Figure 3.

Thermal stability measurement of microcapsules. (a) At duration of 30 min, the shape changes of C22@GO and C22@GO–CNT at around 50 °C are shown. No detectable leakage was observed for C22@GO–CNT capsules. TG (b) and DTG (inset) curves of bulk C22, C22@GO, C22@CNT, and C22@GO–CNT are demonstrated. The TG curve of C22@GO–CNT in decreasing process exhibits two-step weight loss that, respectively, corresponds to decomposition of alkanes (200–300 °C) and degradation of carbon shells (400–500 °C). A postponed decomposition was obvious by comparing with other samples. DSC curves (c) of C22@GO–CNT at 10th, 50th, and 100th thermal cycle were obtained at the rate of 5 °C/min. During the measurement, the melting and crystallizing points varied slightly. DSC curves (d) of bulk C22, C22@GO, C22@CNT, and C22@GO–CNT at the rate of 10 °C/min are displayed. The subcooling circle, delayed structural change, happens at C22@GO, C22@CNT, and bulk C22 in between 37 and 40 °C.^49,50