The Modification of Polyamide 6 Films by the Thallium Sulfide Layers Using Dodecationic Acid

Abstract

By a study of IR and UV absorption spectra it is shown that the dodecathionate anions are sorbed-diffused into a
polyamide 6 films if they are treated with the water solution (0.002 mol⋅dm–3, 20 °C – 50 °C) of dodecathionic acid,
H2S12O6. The values of sulfur concentration obtained in polyamide 6 (up to ∼250 mg⋅g–1) are significantly higher than
those obtained in the studies in which the sorption of lower polythionates – trithionate, S3O6
2–, tetrathionate, S4O6
2–, and
pentathionate, S5O6
2–, – by polyamide 6 films has been studied. The concentration of sorbed dodecathionate ions
increases with the increase of duration of treatment and temperature of a H2S12O6 solution. The thallium sulfide, TlxS,
layers are formed in the surface of polyamide 6 film if the sulfured polymer is treated with alkalified (0.015 mol⋅dm–3
NaOH) 0.1 mol·dm–3 solution of Tl2SO4 at 80 °C temperature: the anionic particles S12O6
2– containing sulfur atoms of
low oxidation state react with the Tl(I) ions. The conditions of a polymer initial sulfuration determine the amount of
thallium and the composition of sulfide layer: the amount of thallium in the polyamide 6 film increases with the increase
of duration and temperature of initial sulfuration, and varies from ∼25 mg·cm–2 to ∼250 mg·cm–2; the stoichiometrical
composition of TlxS layers on polyamide 6 formed according the data of chemical analysis varies from ∼Tl0.15S to Tl1.2S.
The results of X-ray structural analysis confirmed the formation of thallium sulfide layers in the surface of polyamide 6.
The phase composition of layer changes depending on the conditions of initial treatment in a H2S12O6 solution too. Four
thallium sulfide phases, TlS, Tl2S2, Tl4S3 and Tl2S5 were identified in the composition of the layers by X-ray diffraction
but the maxima of TlS and Tl2S5 phases predominate in the diffractograms. The regularities determined enable formation
by sorption-diffusion method of thallium sulfide layers of desirable composition using the dodecathionic acid as a
polyamide 6 sulfuration agent.