Fractality and metastability of a complex amide cross-linked dipodal alkyl/siloxane hybrid
2014
Nunes, S. C. | Ferreira, C. B. | Ferreira, R. A. S. | Carlos, L. D. | Ferro, M. C. | Mano, J. F. | Almeida, P. | de Zea Bermudez, V.
A novel room-temperature white light emitter amide-cross linked alkyl/siloxane hybrid material (amidosil A) was produced by self-organization through the rational design of the precursor. This hybrid displays a highly complex hierarchical architecture composed of two lamellar bilayer structures, the relative spatial arrangement of which yields a multiplicity of ordered nanodomains with variable shapes and sizes, some of them persisting at the microscale. Macroscopically A was obtained as clusters of hydrophobic hemispherical and spherical micro-objects exhibiting a lettuce coral-like pattern, which represent unprecedented pieces of evidence illustrating the principles of self-similarity and demonstrating that the time scale of biomimetic morphogenesis in this non-bridged silsesquioxane is similar to that in biological systems. Heating metastable A above the order/disorder phase transition acted as an external quake driving the material to another metastable state, which has persisted for more than 12 months, and was manifested as a marked change of all the macroscopic properties. The occurrence of the self-organization process operating on A, instead of a self-directed assembly, is primarily associated with the formation/rupture of hydrogen bonds, therefore supporting that these interactions are critical factors dictating on what side of the self-assembly/self-organization boundary a non-bridged silsesquioxane system will evolve.
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