Hierarchical Porosity in Silica Thin Films by a One-Step Templating Strategy Using a Stimuli-Responsive Bioderived Glycolipid

Abstract

Hierarchical porosity in thin films obtained with the evaporation induced self-assembly method is a major challenge that is generally accomplished by combining different templating compounds or strategies, each one typical for a given size range. For instance, for small–medium-sized pores (below 20 nm) a library of surfactants exists, while colloids and polymers, as well as phase separation and water condensation strategies, are used for large mesopores to macropores (up to several micrometers). Here, we report the pH-dependent templating effect using a class of entirely bioderived, functional glycolipids obtained from the culture broth of the yeast Starmerella bombicola. We show that these compounds can be used to achieve a micro-to-macro hierarchical porosity in a one-step process by simply tuning the solution pH and without using any additional cosurfactant, cosolvent, or pore-swelling agent. Small-angle X-ray scattering, transmission electron microscopy, scanning electron microscopy, and ellipsoporosimetry data show the multiscale porous texture of silica thin films.