Preparation of highly oriented organic–LDH hybrid films by combining the decarbonation, anion-exchange, and delamination processes

Abstract

For the preparation of highly-oriented thin films of organic–LDHs (layered double hydroxides) with Mg/Al = 2 and 3, highly-oriented LDH films with anion-exchangeability were prepared (a) by casting a CO₃²⁻LDH water suspension onto a glass slide, followed by decarbonation in an HCl–NaCl solution and anion-exchange to ClO₄⁻LDH, and (b) by casting delaminated ClO₄⁻LDH in formamide (FA) onto a glass slide. These ClO₄⁻LDH films formed on glass substrates were further anion-exchanged by p-toluenesulfonate anions (Tos⁻) to produce organic–LDH hybrid films with retention of their orientation and transparency. The direct delamination of Tos⁻LDH in FA was also successfully conducted, and a highly-oriented Tos⁻LDH hybrid film was obtained by casting the colloidal Tos⁻LDH solution on a glass slide. These three procedures offered well-oriented organic–LDH films, and especially, the process involving the delamination treatments gave more dense and transparent films.