The authors report the formation of highly oriented wrinkling on the surface of the bilayer [polystyrene (PS)/poly(vinyl pyrrolidone) (PVP)] confined by a polydimethylsiloxane (PDMS) mold in a water vapor environment. When PVP is subjected to water vapor, the polymer loses its mechanical rigidity and changes to a viscous state, which leads to a dramatic change in Young's modulus. This change generates the amount of strain in the bilayer to induce the wrinkling. With a shape-controlled mold, they can get the ordered wrinkles perfectly perpendicular or leaned 45 degrees to the channel orientation of the mold because the orientation of the resultant force changes with the process of water diffusion which drives the surface to form the wrinkling. Additionally, they can get much smaller wrinkles than the stripe spacing of PDMS mold about one order. The wrinkle period changes with the power index of about 0.5 for various values of the multiplication product of the film thicknesses of the two layers, namely, lambda approximately (h(PS)h(PVP))(1/2).

In the present study, the extraction of zinc(II) and cadmium(II) with mixtures of neutral organophosphorus extractants (aliphatic trialkyl phosphine oxide, Cyanex 923, or branched cyclic trialkyl phosphine oxide, Cyanex 925) and amine extractants (N,N-di(1-methylheptyl) acetamide, N503, or trialkyl amine, N235) has been investigated. Synergistic effects were observed for zinc(II) with Cyanex 923 þ N503 and for cadmium(II) with Cyanex 923 þ N235 and Cyanex 925 þ N235. However, the other mixing systems do not have synergistic effects on zinc(II) and cadmium(II). According to the different extraction effects, the separation possibilities of zinc(II) and cadmium(II) are discussed. The extraction mechanisms have been studied with the methods of slope analysis and constant moles in the three synergistic systems. The extracted compounds, the equilibrium constants, and thermodynamic functions have also been determined.

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