Synergistic flame retardant weft-knitted alginate/viscose fabrics with MXene coating for multifunctional wearable heaters

Flexible wearable heaters have received increasing attention in energy-saving, diverse personal thermal requirements, and healthcare management. Herein, considering the fire safety application of wearable heaters, the biodegradable alginate fibers and flame retardant (FR) viscose fibers are attempted to mix and weft-knit into the fabric, which interestingly exhibits synergetic flame retardancy with low afterflame time, afterglow time, and peak heat release rate. Further, assisted by the highly conductive Ti3C2Tx (MXene) nanosheets on the surface of the fabric and the periodic nested loops of the knitted fabric, the integrated fabrics possess excellent electrical performance (2Ω sq−1) with the MXene content of 9.13 wt%, electromagnetic interference (EMI) shielding efficiency of 55 dB in the X band, preferable Joule heating performance under safe low voltage (123 °C at 3.5 V) and sunlight/far-infrared heating performance. The superior flame retardancy and multifunctional properties arose from the high-temperature induced well-constructed char layer, unique functionality of interconnected MXene network and multiple scattering of light or wave. Combined with the superior flame retardancy and multifunctional properties, the weft-knitted alginate/FR viscose fabrics with MXene coating become the ideal candidate materials in the fields of wearable heaters with high safety.