Donor-Acceptor Interactions at Interfaces

Abstract

The free energy change per unit area on separating an interface (the work of adhesion, W_A ) is composed of a variety of interactions: where superscripts are d for London dispersion forces, h for hydrogen-bonding, ab for acid-base interaction, p for dipole-dipole interaction, and i for induced dipole-dipole interaction. The work of cohesion can be similarly separated into components of surface tension(γ ^d , γ ^h , γ ^ab , γ ^p , γ ⁱ ).The success of predicting W_A ^d by 2√γ₁ ^d γ₂ ^d , as derived from London force theory, has led others to propose that W_A ^h = 2√γ₁ ^h γ₂ ^h , etc. However, there is no theoretical basis for the latter and we see that present experimental data indicate rather clearly that at a solid-liquid interface W_A ^h is directly proportional to γ _L ^h :