Hydrophilicity regulation and microstructure change of Ethylene-tetrafluoroethylene copolymer films grafted acrylic acid by irradiation-induced co-grafting

Abstract

The surface hydrophobicity of Ethylene-tetrafluoroethylene copolymer(ETFE) films limits its application in functional membranes. However, the surface energy of ETFE films is extremely low and the interface compatibility is poor, which makes it difficult to modify the surface hydrophilicity. In this work, acrylic acid was grafted onto ETFE films by the irradiation-induced co-grafting method. The effects of adsorbed dose on the structure and properties of grafted ETFE films were investigated by the various characterization methods. By irradiation- induced grafting method, the surface of ETFE films were successfully grafted with acrylic acid to modify its hydrophilicity. With the increase of absorbed dose, the contact angle of the ETFE was reduced from 102° to 44°, the microstructure and the natural crystallization area was destroyed, and the radius of gyration decreased. The destruction of the structure leads to a decrease in mechanical properties. When the absorbed dose is 60 kGy, it exhibits good hydrophilicity and mechanical properties. The contact angle, breaking strength and elongation at break are 68°, 13.0 MPa and 72.6 %, respectively. It clarified the effect of adsorbed dose on the structure of ETFE grafted acrylic acid, and helped to expand the application of ETFE in battery separators and other fields.