Polymerization and surface analysis of electrically-conductive polypyrroleon surface-activated polyester fabrics for biomedical applications

A new synthetic route is reported for the synthesis and covalent bonding of electrically conductive polypyrrole to a poly(ethylene terephthalate) fabr ic. It involves a three-step process including surface phosphonylation and graft polymerization from the gaseous phase. In the first step, the fibre s urfaces art: activated using phosphorus trichloride. Then, 1-(3-hydroxyprop yl) pyrrole is introduced and grafted to the phosphorus chloride to create an ester bond between the fibres and the pyrrole. Finally, the pyrrole-graf ted fibres are dipped in an aqueous FeCl3 catalyst and exposed to pyrrole m onomer vapor for the final polymerization. This last step creates an electr ically conductive polypyrrole layer covalently linked to the poly(ethylene terephthalate) fibres. ESCA analysis indicates a high degree of phosphonyla tion and grafting of the anchor molecules. Scanning electron microscopy rev eals an overall smooth and uniform surface coating of polypyrrole on the po lyester fibres. The use of ATR-FTIR spectroscopy is not able to distinguish between polypyrrole-coated and non-coated fabrics because of the extremely thin polypyrrole layer. Measurements of dynamic surface wetting indicated that the polypyrrole-coated fabric is more hydrophilic than the untreated c ontrol. With values for surface resistivity in the range 10(4)-10(5) Ohm/sq uare, such polypyrrole-coated fabrics are considered attractive candidates for biomedical applications.