Unexpected hydrophobic to hydrophilic transition of PET fabric treated in a deep eutectic solvent of choline chloride and oxalic acid

The hydrophilic wettability of polyethylene terephthalate (PET) fabric was modified by physical etching and limited chemical modification using deep eutectic solvent (DES) of choline chloride and oxalic acid without changing the crystal structure and mechanical properties of PET fabric. The surface morphology and structure of the as-treated PET fabric were investigated by SEM, XPS, FTIR, and XRD. The surface morphology of the fabric became rough after being treated with the DES solvent at 60 °C for 2 h, and its polarity was enhanced due to the swelling and chemical effect of the DES solvent; hence, the surface of the PET fabric dramatically changed from hydrophobic to hydrophilic. Moreover, the water absorption capacity of the PET fabric treated by the DES solvent was significantly improved. In comparison to the pure PET fabric, the treated PET fabric manifested excellent antistatic and dyeing properties.