Nuclear Magnetic Resonance Study of Interlayer Water in Hydrated Layer Silicates

Abstract

Resonance data have been obtained for the intracrystalline water in homo‐ionic vermiculite, montmorillonite, and hectorite in both the crystalline and osmotic swelling regions, but interpretation is complicated by the anisotropic susceptibility of the crystals and the effects of particle size, discussed briefly in an appendix. Because of this, only a minimum value can be obtained for the proton mobility, and it is shown that in the osmotic swelling region molecular motion may not be very different from that in free water. The proton mobility in the crystalline swelling region varies with the water content. A single‐crystal study of vermiculite containing two sheets of water between silicate layers shows that the water molecules are in hindered rotational movement. A transition to a freely reorienting phase is dependent on particle size. The results are applied to some aspects of the theory of gels and of interparticle forces.