Composites of Hydroxyethyl Cellulose and Calcium Sulfate Whiskers Enable Durable Thermoelectric Devices with High Flame Retardency

The high-temperature-resistant composite matrix material, derived from one-dimensional inorganic nano materials rather than the traditional organic polymer matrices used in flexible devices, can significantly broaden the application range of wearable devices, particularly in high-temperature or open-flame environments. In this study, flame-retardant and high-temperature-resistant composite nanofilms were prepared by solution casting with hydroxyethyl cellulose (HEC) bonded to calcium sulfate whiskers (CSW). When the HEC content reached 20%, the composite films exhibited a tensile strength of 8.20 MPa and a limiting oxygen index exceeding 44.5%. Molecular dynamics simulations indicated that the electrostatic and van der Waals interactions between HEC and CSW were strongest in the CSW/HEC20 sample with a binding energy of 9227.23 kJ/mol. Furthermore, when the CSW/HEC20 film was integrated with silver nanowires, a flexible electrothermal converter was successfully fabricated, providing a base material for high-temperature-resistant electronic devices.