▎ 摘　　要

In this study, a novel bioinspired deep eutectic solvent (DES) was synthesized and functionalized with graphene to prepare G-DES. DES was synthesized in the presence of choline chloride and guanidine, which are biocompatible materials and phosphoric acid, an inexpensive phosphorous source. The flame retardant (FR) efficiency of DES and G-DES coated cotton fabrics was checked by detailed flame tests such as spirit flame test, limiting oxygen index (LOI), and vertical flammability test (VFT). According to the simple flame test result, as-synthesized DES and G-DES coated cotton fabrics withstood continuous flame for 180 and 300 s, respectively, emitting a small amount of smoke. At the same time, the control cotton fabric caught fire and completely burned out within 15 s. Additionally, DES and G-DES coated cotton fabric showed excellent LOI results, 39.5% and 52.5%, respectively. In the case of VFT, DES and G-DES coated cotton fabric produced less char length, such as 8 mm and 2 mm, respectively, indicating an excellent flame retardant property of DES and G-DES. The results revealed that DES could be applied as a transparent FR, which does not change the color of the cotton fabric. Furthermore, G-DES-coated fabric exhibited excellent flame retardancy. Thus, the novel as-synthesized DES and G-DES opens new avenues for the use of bioinspired nanocomposites as FRs for cotton fabrics.