Time Dependence of Self-Assembly Process For the Formation of Inorganic-Organic Hybrid Nanolayers

There is increasing interest in self-assembled materials for energy storage, flexible electronics and hydrophobic barriers. Inorganic/organic hybrid thin films and especially organosilane-based coatings already have demonstrated their ability to achieve those goals. However, some fundamental points of their formation process by molecular self-assembly remain unexplained. Although the literature widely reports the effect of temperature on the final nanostructure, until now, no one has taken into account the importance of time during their synthesis. The main objective of this study was to improve and complete the understanding of mechanisms responsible for the self-organization of organic/inorganic molecules into a highly ordered, layered structure. Indeed, by including gelation time as the main parameter during the preparation of nanostructured films, we have shown that it is among the major criteria controlling molecular conformation. By completing this research, we have filled a gap in the knowledge concerning the time dependence of the preparation of self-assembled molecules. We expect this work to be of general interest to all material engineers wanting to synthesize and control the internal structure of inorganic/organic hybrid thin films

Supramolecular Nanolayer Reconfiguration after Molecular Intercalation

We examined the structural reconfiguration after intercalating foreign additives, that is, tetramethoxysilane (TMOS), within already formed supramolecular nanolayers of hexadecyltrimethoxysilane (HDTMS). Our experiments indicated that the newly formed interdigitated structure is a thermodynamically more stable configuration. Even after the HDTMS formed initial bilayer-by-bilayer structures, mixing of these aggregates with foreign additives at room temperature can change the original structure to a more compact configuration (i.e., interdigitated). Our MD simulations further revealed that the most favorable organization for this interdigitated stacking appears to be a formation of relatively small domains of HDTMS and TMOS molecules, supporting our proposal of a heterogeneous mixing before reorganization. Although the coassembly of binary or multiple building blocks has previously been used to modify a supramolecule or to produce a supramolecular composite, the modification of already formed supramolecules via molecular intercalation, examined here, provides a flexible path for decorating more advanced supramolecules without disturbing their complex assembly conditions. Includes Supporting Information