Comprehensive study of pulsed UV-laser modified polyamide fibers

Polyamide fibers (nylon 6) are modified by UV-radiation using a pulsed excimer laser with different treatment parameters. The treated samples are characterized by using a scanning electron microscopy (SEM), tapping mode atomic force microscopy (TM-AFM), x-ray photoelectron spectroscopy (XPS), and chemical force microscopy (CFM). Depending on the conditions during the irradiation, different surface modifications are obtained which can generally be distinguished as high-fluence (above the ablation threshold) and low-fluence (below the ablation threshold). Topographical results indicate that ripple-like structures of micrometer size are developed under high-fluence laser irradiation. On the contrary, smaller sub-micron structures are formed by low-fluence treatment. XPS results show that bond scission occurs on the polymer surface under the action of high-fluence while low-fluence modifies the sample by an oxidative process. Changes in surface chemical properties of the laser-irradiated polyamide are supported by chemical force microscopy experiments with gold-coated AFM tips modified with -COOH terminated self-assembled alkanethiol monolayers (SAMs).