Binding of counter ions

In contrast to Equations 7 and 8, based on the binding of counter ion to micelle, an equation including a form for the electrostatic part of free energy of micelle formation, Fgi, evaluated from double... 

The binding of counter-ions to polyions derived from polyelectrolytes is relevant to the biophysics of proteins, nucleic acids, and similar biomolecules. This is discussed in Sect. 2.7.2. Here some other aspects of aqueous ions of importance in the present context are dealt with. 

FIGURE 1.32 Micelle structure (a) inner part = liquid paraffin-like outer polar part (b) solubilization of apolar molecule and (c) binding of counter-ion to the polar part (schematic). 

Electrochemical reactions are driven by the potential difference at the solid liquid interface, which is established by the electrochemical double layer composed, in a simple case, of water and two types of counter ions. Thus, provided the electrochemical interface is preserved upon emersion and transfer, one always has to deal with a complex coadsorption experiment. In contrast to the solid/vacuum interface, where for instance metal adsorption can be studied by evaporating a metal onto the surface, electrochemical metal deposition is always a coadsorption of metal ions, counter ions, and probably water dipols, which together cause the potential difference at the surface. This complex situation has to be taken into account when interpreting XPS data of emersed electrode surfaces in terms of chemical shifts or binding energies. 

Figure 2. Representation of the possible site forms in the site-binding model which includes the effect of counter-ion adsorption, combined with a diagram of charges and potentials at the insulator/electrolyte interface. Reproduced with permission from Ref. (14). Copyright 1983, North Holland.

As previously mentioned, molecules that are present within the interface may be able to bind or release electrons from the outer electron hull that surrounds the positively charged proton-neutron core—i.e., they can be ionized. In systems with interfacial boundaries containing ions that carry a charge, a spatial distribution of counter ions surrounding the interface will develop. The number of counter ions will decrease as the distance from the interface increases. The counter ion atmosphere is also referred to as the ion cloud. The... 

This volume covers the structural relations between thermotropic and lyotropic liquid crystals (Chapters 1 and 2) and compares them with the micellar systems (Chapter 3). The interfacial aspects and the accompanying stability problems are covered in Chapters 5 and 6. The molecular dynamics in liquid crystals, the importance of water structure and of counter-ion binding for their stability are three essential factors for long range order systems, which are treated in Chapters 7, 8, and 9. The final chapter by E. J. Ambrose illustrates the change of order in a biological system under malignant conditions. 

---