| Abstract: | Poor flame retardancy of polyurethane foam (PUF) limits its practical application in many fields. Here, flame‐retardant performance of PUF is improved by a simple dip‐coating method. Halloysite nanotube (HNT) coating can be uniformly bonded to PUF surfaces via hydrogen‐bonding interactions, which is confirmed by element mapping and X‐ray photoelectron spectra. Density and mechanical properties of PUF increase with the concentration of HNT suspension, while porosity of the foam decreases with HNT loading. Weight ratio of HNTs to PUF in the composite can be achieved as high as 65.2%. Surfaces of PUF transfer from hydrophobic to super‐hydrophilic after HNT coating, and the water contact angle decreases from 116° to 0° after HNT coating. As a result, methylene blue adsorption capacity of HNTs‐coated PUF increases from 0.02 to 0.15 mg g?1, and adsorption efficiency can reach 98% after 10 s. HNT coating can prevent PUF from burning and dripping, which suggests that flame‐retardant performance of PUF is significantly improved by HNTs. This work establishes a general procedure for improving flame retardancy and dye absorbency of polymer materials by simple dip‐coating of environmental‐friendly clay nanotubes, which shows great potential in high‐performance polymer and functional composite materials. |
