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Self-organize structuring polymeric and hybrid nanocomposite materials

Akihiro Sato Laboratoire des systèmes complexes hors équilibre, Institut de Science et d’Ingénierie Supra-moléculaire (ISIS), Université de Strasbourg

Progress in materials science, supported by recent advances in design flexibility and controllability, allows for the development of novel materials. In particular, controlled structuring of either small building blocks or bulk materials that self-organize into highly functional nano-materials is an important aspect in the development of nanotechnology. Self-organized structures are of use in a whole range of nanotechnology, and hold a pivotal role in the development of advanced materials, whose functions can be drastically altered compared to their unstructured, bulk materials. This presentation will discuss two different types of self-organization : (i) the top-down self-organization in nanoporous alumina ; (ii) the bottom-up self-organization in supramolecular structures. In the former case, organic-inorganic nanocomposites possessing periodic variations of density and elastic properties at length scales commensurate with the wavelength of high frequency hypersonic phonons (GHz) will be addressed. Nanoporous alumina provides a 2D confined space where self-organization processes such as crystallization and phase separation can be controlled due to confinement-induced morphologies, thus resulting in different elastic impedances. By measuring the dispersion ω(k), it will be shown that the elastic wave propagations sensitively depend on the constituents of the nanocomposites and their local thermo-mechanical properties. In the latter case, field-induced self-assembly of ben-zene-tricarboxamide based molecules will be addressed. One of the major challenges in supra-molecular chemistry is to be able to grow self-assembled structures with well-defined size and/or shape. In order to achieve this goal, several studies have appeared by using e.g., exact stoichiometry of the building blocks, steric hindrance, electrostatic repulsion, or template self-assembly. Here, a different approach is explored that uses magnetic fields to control the size of supramolecular self-assemblies since benzene-tricarboxamide based molecules contains chelating moieties and form a complex with various trivalent ions such as gadolinium (G3+) and yt-trium (Y3+). It will be shown that the assemblies grow or shrink depending on the type of ions.