カチオン界面活性剤水溶液中におけるグラフト化ナイロン6繊維のζ電位と表面吸着性

抄録

The surface adsorbability of a cationic surfactant on nylon 6 fibers grafted with acrylic and methacrylic acids was studied by measuring the ζ-potential of the fibers in an aqueous solution of the surfactant, N-dodecylpyridinium bromide (DPB). The amount of adsorbed DPB per unit area of the fibers was calculated from the ζ-potential value. With increase in DPB concentration, the ζ-potentials of the ungrafted and the grafted fibers changed from negative to positive in sign and the amount of DPB adsorbed increased. Thus possibly, electrostatic and van der Waals forces between the fibers and cationic surfactant may contribute to surface adsorbability. The amount of DPB adsorbed decreased with increase in the degree of grafting.
The free energy of adsorption (ΔG) of DPB on the fibers was calculated from the equation of Ottewill-Watanabe. With increase in the degree of grafting, the negative value of ΔG decreased. The positive entropy of adsorption of the ungrafted and the grafted fibers indicates entropic interactions (the formation of hydrophobic bonds) to possibly be important as the driving force for the adsorption of DPB on the surfaces of the fibers.
Based on the above findings, the surface adsorbability of the cationic surfactant on the grafted fibers is concluded to be less than that on ungrafted fibers since the water-soluble polymer layer was formed at fiber surfaces by grafted polymer chains.