Antimicrobial Expanded Polytetrauoroethylene Film Prepared by γ-ray Radiation Induced Grafting of Poly(acrylic acid)

The simultaneous γ-ray-radiation-induced grafting polymerization of acrylic acid on ex-panded polytetra fluoroethylene (ePTFE) lm was investigated. It was found that the degree of grafting (DG) of poly(acrylic acid) (PAA) can be controlled by the monomer concentration, absorbed dose, and dose rate under an optimal inhibitor concentration of Fe²⁺=18 mmol/L. SEM observation showed that the macroporous structure in ePTFE films would be covered gradually with the increase of the DG of PAA. The prepared ePTFE-g-PAA film was im-mersed in a neutral silver nitrate solution to fabricate an ePTFE-g-PAA/Ag hybrid film afterthe addition of NaBH₄ as a reduction agent of Ag to Ag atom. SEM, XRD, and XPS results proved that Ag nanoparticles with a size of several tens of nanometers to 100 nanometers were in situ immobilized on ePTFE film. The loading capacity of Ag nanoparticles could be tuned by the DG of PAA, and determined by thermal gravimetric analysis. The quan-titative antibacterial activity of the obtained ePTFE-g-PAA/Ag hybrid lms was measured using counting plate method. It can kill all the Escherichia coli in the suspension in 1 h. Moreover, this excellent antibacterial activity can last at least for 4 h. This work provides a facile and practical way to make ePTFE meet the demanding antimicrobial requirement in more and more practical application areas.