Kinetics, Thermodynamics, and Dynamics in Organosilane Self-Assembly

Organosilane self-assembly is a widely studied template-free approach to design organic inorganic hybrids structured at the nanometer scale. The main emphasis has been focused so far on novel precursor architectures and sol gel preparation methods to drive the self-assembly. This feature attempts for the first time a thermodynamic, kinetic, and dynamic description of the organosilane supramolecular assembly. Condensation and hydrolysis rates are the main kinetic parameters impacting the self-assembly, while organic moiety, alkoxy head, temperature, or relative humidity determine essentially the energetic contributions of the self-association, and therefore, form part of a thermodynamic description. In terms of dynamics, the gradual conversion of the isotropic precursor into a cross linked hybrid nanostructure was assessed by time resolved infrared spectroscopy combined with small angle X-ray scattering. To reveal the mechanism of self-assembly, our system is simplified to the main ingredients: n-dodecyltrimethoxysilane (C12H25Si(OCH3)(3)) as a model organosilane building block and a photoacid generator (C12H25)(2)Phi I-2(+) SbF6-), deposited as a photolatent micrometric film. UV light governs the sol-gel polymerization kinetics through the controlled liberation of Bronsted superacids.