*3.5. DSC*

The DSC curves were obtained using a DSC instrument (DSC 204 F1, Netzsch, Selb, Bavaria, Germany) and the method reported by Kun et al. [55]. A certain amount of the samples (approximately 2–5 mg) were loaded into the bottom of an aluminum crucible and pressed with a lid. The samples were then transferred to the DSC instrument. During DSC scanning, the sample was cooled quickly with liquid nitrogen to −60 ◦C from room temperature and then heated to 200 ◦C at a heating rate of 10 ◦C/min in nitrogen atmosphere (purge flow of 50 mL/min and protective flow of 70 mL/min). Indium metal standard was used for temperature calibration.

### *3.6. Thermal Stability*

The thermogravimetric analysis was conducted according to the methods described by Krishnakumar et al. [56] with some modifications. Thermogravimetric analysis (TGA2,

Mettler Toledo Co. Ltd., Shanghai, China) used continuous nitrogen (flow rate 50 mL/min) in the sample chamber. Approximately 1 mg of the sample was placed in a crucible and pressed to create complete contact followed by sequential heating from 20 ◦C to 600 ◦C at a constant heating rate of 10 ◦C/min; the thermogravimetric data at the first heating curve were then recorded.
