Relaxation time and viscosity of water near hydrophilic surfaces

Recently results of microwave spectroscopy have shown that the water relaxation time is lengthened near the surface of aggregates of hydrogen bond-forming molecules, an effect corresponding to an enhanced viscosity [1–3]. In this communication properties of the so-called bound water are treated by a percolation calculation on the water cluster sizes. The values combined with the statistical model of the dielectric response of bulk water by Haggis et al. [4] yield the bound water relaxation time and in this way its viscosity. Fair agreement with the experimental data is obtained. The new analysis represents a keystep for a better understanding of bound water in physico-chemical and biological systems.Dedicated to Professor Karlheinz Seeger on the occasion of his 60th birthday