engleski

pH-dependent charging of poly(aniline) synthesized at surfaces of polyester fabrics

Poly(aniline) is probably the oldest known organic seminconductor that is easily synthesized both in solution and at interfaces. This makes it an attractive material for the production of flexible electronics, but also for achieving antistatic properties of textiles. The protonation behavior of poly(aniline) in the forms of emeraldine base (non-conducting) and emeraldine salt (conducting), bound to polyester textile fabric surface coated with TiO2 nanoparticles (anatase, d ~ 5 nm), was determined from the potentiometric titrations and compared with its protonation behavior when bound to the pure polyester surface. The protonation behavior of the two emeraldine forms (salt vs. base) is similar both in the presence and absence of TiO2, exhibiting monotonic charging in a broad pH range. This shape of the curve is caused by the delocalization of the bound protons, and thus a monotonically increasing electrostatic field with decreasing pH. Nevertheless, the pH-dependence of the overall surface charge, as determined from the zeta potential measurements, shows a significantly different behavior for the poly(aniline) bound to TiO2, with a noticeable negative shift of the isoelectric point. These two results point to the conclusion that at the polyester/TiO2 surface, polyaniline is present in the form of a polymer brush, whereby its chains extend far beyond the shear plane.

Polyaniline; conducting; polymer; polyester; fabric; surface; charge; pH; pK

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