Self-Assembling of Tetradecylammonium Chain on Swelling
High Charge Micas (Na-Mica‑3 and Na-Mica-2): Effect of Alkylammonium
Concentration and Mica Layer Charge
posted on 2015-04-21, 00:00authored byM. Carolina Pazos, Agustín Cota, Francisco
J. Osuna, Esperanza Pavón, María D. Alba
A family
of tetradecylammonium micas is synthesized using synthetic swelling
micas with high layer charge (NanSi8–nAlnMg6F4O20·XH2O, where n = 2 and 3) exchanged with tetradecylammonium cations.
The molecular arrangement of the surfactant is elucidated on the basis
of XRD patterns and DTA. The ordering conformation of the surfactant
molecules into the interlayer space of micas is investigated by IR/FT, 13C, 27Al, and 29Si MAS NMR. The structural
arrangement of the tetradecylammonium cation in the interlayer space
of high-charge micas is more sensitive to the effect of the mica layer
charge at high concentration. The surfactant arrangement is found
to follow the bilayer-paraffin model for all values of layer charge
and surfactant concentration. However, at initial concentration below
the mica CEC, a lateral monolayer is also observed. The amount of
ordered conformation all-trans is directly proportional
to the layer charge and surfactant concentration.