Self-assembly of montmorillonite platelets during drying

This work is prompted by the quest for nanocomposites in which ordered, layered reinforcement preforms similar in structure to the arrangements seen in nacre are achieved without complex automated layer-by-layer assembly. Lamellar structures were obtained in montmorillonite films simply by slow drying without the use of additives. Clay alignment was found in films derived from suspensions of less than 0.9 vol%, ranging over a pH range of 2–11, at low drying rates and with both the natural ionic strength of the clay suspension and adjusted ionic strength. The greatest degree of order was found at the unadjusted pH and ionic strength. This method offers a potentially simple way of preparing clay preforms for polymer-clay nanocomposites at a drying rate at or below 23 nm s−1. (paper)