Fractality and metastability of a complex amide cross-linked dipodal alkyl/siloxane hybrid

abstract

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.

keywords

ORGANIC-INORGANIC HYBRIDS; BRIDGED SILSESQUIOXANES; ALKYL CHAINS; LAMELLAR STRUCTURE; QUANTUM YIELDS; LIGHT EMISSION; MONOLAYERS; SILICA; PHOTOLUMINESCENCE; CONFORMATION

subject category

Chemistry

authors

Nunes, SC; Ferreira, CB; Ferreira, RAS; Carlos, LD; Ferro, MC; Mano, JF; Almeida, P; Bermudez, VD

our authors

acknowledgements

This work was supported by Fundacao para a Ciencia e a Tecnologia (FCT) and FEDER (contracts PTDC/QUI-QUI/100896/2008, PTDC/CTM-BPC/112774/2009, PEst-C/CTM/LA0011/2011, Pest-C/CTM/LQ0011/2013, Pest-OE/QUI/UI0616/2014 and PEstOE/SAU/UI0709/2014) and by COST Action No MP1202

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