Comparative study of grafting a polyampholyte in a fluoropolymer membrane by gamma radiation in one or two-steps

• Graft copolymers by the ionizing radiation can be obtained in one or two steps.
• Gamma-radiation was utilized to prepare grafted PVDF membranes.
• Stable alkyl and peroxy radicals are stabilized by the crystalline zones.
• In 100 % graft of two monomers, the entire surface of membrane is totally covered.

Binary graft copolymerization of pH-sensitive monomers (N,N-dimethylaminoethyl methacrylate, (DMAEMA) and acrylic acid (AAc) onto polyvinylidene fluoride (PVDF) membranes with pore sizes of 0.22 and 0.45 μm was conducted by one and two-steps grafting using a 60Co gamma radiation source (Gammabeam 651 PT). The DMAEMA and AAc monomers were grafted by an oxidative pre-irradiation method in one-step grafting to obtain PDVF-g-(DMAEMA-co-AAc), and both direct irradiation and an oxidative pre-irradiation method were used to obtain the graft copolymer (PVDF-g-DMAEMA)-g-AAc in two-steps grafting. The optimal conditions, such as reaction time, temperature, solvent, monomer concentration and dose, were studied, the aim of this work was to investigate how these factors affecting the graft percent of DMAEMA and AAc prepared in one and two-steps grafting and their structural differences and also characterize the grafting membrane through analytical techniques.