Tripodal polyhedral oligomeric silsesquioxanes as a novel class of three-dimensional emulsifiers

Abstract

Tripodal amphiphilic molecules toward organic–inorganic hybrid emulsions were successfully synthesized based on incompletely condensed polyhedral oligomeric silsesquioxanes (POSSs). The three silanol groups provide an excellent scaffold for the construction of three-dimensional amphiphilic molecules, thus well-defined tripodal amphiphilic POSS derivatives were readily synthesized. Thermal analyses revealed that an incompletely condensed POSS exhibited lower crystallinity without loss of thermal stability in comparison with a completely condensed POSS, whereas readily forms aggregates because of its high crystallinity. The newly synthesized tripodal amphiphilic POSSs possessed good solubility in water and effectively stabilized oil-in-water emulsions, while a conventional mono-substituted amphiphilic POSS did not work as an emulsifier because of its lack of water solubility. The prepared organic–inorganic hybrid emulsions were stable against coalescence, and no demulsification occurred over 1 month. Novel molecular design for organic–inorganic emulsifiers has been developed based on an incompletely condensed polyhedral oligomeric silsesquioxane (POSS). Hydrophilic poly(ethylene) glycol chains were introduced to the three silanol groups of heptaisobutyl trisilanol POSS. The obtained amphiphilic POSSs worked as good emulsifiers, and the emulsions were stable for at least 1 month without coalescence of the droplets. The simple synthetic procedure, the well-defined three-dimensional structure and the obtained stable emulsions are advantageous in developing organic–inorganic hybrid materials.