Interaction of Poly(ethylene glycol) Monoalkyl Ethers with Synthetic Saponites in Aqueous Suspensions:  A Multinuclear Magnetic Resonance Study

Abstract

Synthetic saponites were suspended in aqueous solutions of poly(ethylene glycol) monomethyl and monooctyl ethers and studied by NMR techniques. Analysis of water deuteron quadrupolar splittings, 23Na NMR relaxation rates of counterions, 13C NMR relaxation rates, and 1H NMR self-diffusion coefficients of oligomers provides a convergent picture on the oligomer interaction with saponites. Both isolated molecules and micelles mainly interact with the lower charged saponites.

A Multinuclear Magnetic Resonance Study of Synthetic Clays Suspended in Water and in Dodecyldimethylamine Oxide Solutions

“…Indeed, the surfactant-clay interaction is modulated by the solid charge, and the strongest interaction is obtained with the octahedrally substituted laponite. Similar observations have been reported for poly(ethylene glycol) monoalkyl ethers C n E m (10,11). The decrease in the 23 Na relaxation times has been assigned to an increase in the electric field gradient (11).…”

“…These data provide a convergent picture on clay-nonionic surfactant interaction (10,11). Dodecyldimethylamine oxide is essentially nonionic at high pH, typically higher than 9, but lowering pH results in an increase of the cationic species.…”

Interaction of a Zwitterionic Surfactant with Synthetic Clays in Aqueous Suspensions: A Multinuclear Magnetic Resonance Study

“…These data provide a convergent picture on clay-nonionic surfactant interaction (10,11). Using a multinuclear approach, we describe in this paper how the behavior of a zwitterionic surfactant (laurylamidopropylbetain: A) is affected by the presence of suspended clays.…”

“…Synthetic saponites with 0.3, 0.35, 0.4, 0.5, and 0.75 charge per half-unit cell were prepared as described previously (10). Full details of syntheses and characterization of saponites are reported in the literature (17).…”

“…Thus, cationic amphiphiles increase the signal intensity by removing sodium ions from the clay interface (18). In contrast, nonionic surfactants do not significantly change the NMR visibility as they are not expected to displace clay counterions (10,28). With zwitterionic detergents, the observation depends on the clay charge (Section A.2.2).…”