Fig. 3-10 ArF-Laser Illumination makes a PFA Surface wettable. Much improved wettability (getting wet in water) is achieved by increasing the laser illumination rather than by chemical treatment.

Fig. 3-11 Wettability of PFA and surface atomic ratios Wettability of PFA is accompanied with the decrease in F/C and increase in O/C atomic ratios on the polymer surface due to the formation of carbonyls with the release of fluorine atoms, as evidenced by XPS analysis.

Fluoropolymer materials, having such excellent properties as heat stability, chemical resistance and electrical insulation, cannot readily be used to make composite or biomedical materials owing to their poor adhesiveness and wettability. We have resolved this problem by photochemical modification of the polymer surface using an excimer laser. Laser irradiation of the polymer results in the removal of fluorine atoms and the introduction of oxygen to form carboxylic acid, thus enhancing the wettability. We have hitherto applied this technique successfully to improve the adhesiveness of PTFE ("teflon" as sold by Dupont, USA) by irradiation with an added small amount of aromatic polymer as an UV absorbent, as well as to improve the wettability of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers by irradiation in carbon monoxide saturated water. The modified polymer is expected to be employed as medical and separator material which needs to be wettable.

Reference A. Okada et al., Endoment with the Wettability on the Surface of Tetrafluoroethylene-Perfluoroalkyl Vinyl Ether Copolymer by Excimer Laser Irradiation, Chem. Lett., 1993, 1637 (1993).

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