Synthesis of nanomaterials in Highly Swollen Liquid Crystals

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EE11.1.1

Synthesis of nanomaterials in Highly Swollen Liquid Crystals Myriam Tokumoto1, Geetarani Surendran1,2, Eduardo Pena dos Santos1, Patricia Kooyman3, Hynd Remita2, Laurence Ramos5, Eric Prouzet1* 1- Institut Européen des Membranes, UMR 5635-CNRS, CNRS, 1919 route de Mende, F-34293 Montpellier Cedex 5 (FRANCE) 2- Laboratoire de Chimie Physique, Bât. 349, UMR 8000-CNRS, Université Paris XI,F- 91400 Orsay Cedex (FRANCE) 3- National Centre for HREM, Delft University of Technology, Rotterdamesweg 137, 2628 AL Delft, (The NETHERLANDS) 4- Laboratoire pour l’Utlisation du Rayonnement Electromagnétique (LURE), UMR 130-CNRS, Université Paris-Sud, F-91402 Orsay Cedex (FRANCE). 5- Groupe de Dynamique des Phases Condensées, UMR 5581-CNRS, Université Montpellier II, F-34095 Montpellier Cedex 05, (FRANCE) [email protected]

ABSTRACT Highly Swollen Liquid Crystals (SLC) that exhibit hexagonal, cubic or lamellar symmetry have been demonstrated to form a new type of soft nanoreactors. These mesophases are formed by a quaternary mixture combining a surfactant, an aqueous solution of inorganic salt, cyclohexane as a hydrophobic swelling solvent and pentanol-1 as a co-surfactant. Unlike previous works that used a "nanocasting" approach in a binary liquid crystal, the composition of these SLC allows syntheses to be proceeded inside the aqueous and/or the organic phase. Therefore inorganic, metallic or organic materials can be prepared and the geometry of the SLC controls the final shape of the prepared by this approach. We will describe various materials that were obtained by different processes in these SLCs: rod-like nanoaggregates of metal nanoparticles were synthesized by chemical reduction in the aqueous part of the hexagonal mesophase, microrods of zirconia were obtained by slow crystallogenesis from hydrated zirconium oxychloride, mesoporous zirconia was prepared by a faster hydrolysis and polymer micro- and nano-fibers were obtained in the organic phase by photopolymerization or radiolysis. We will show how the changements in the SLC structure can modify the structure of the compounds synthesized inside and that this system constitutes a quite universal medium for the preparation of nanomaterials or nanostructured systems.

INTRODUCTION Since several years, physicists have learned to design, observe and organize nanoobjects that usually exhibit specific properties due to their confined size, at least along one dimension, and their high surface over volume ratio. However, due to the increasing amount of materials expected, syntheses based on physical processes could be quickly limited and chemical processes such as those requiring self-organization at the molecular scale, should provide attractive synthesis pathways [1]. Among them, the dynamic properties of soft matter, as for example surfactant-based micellar systems, constitute an efficient driving force for the organization of solid phases, as it was perfectly demonstrated by the surfactant-based preparation of mesostructured oxides [2-6]. An assembly mechani