Instant gels from mixtures of amines and anhydrides at room temperature

Abstract

A series of novel two-component organogel systems comprising of amines and anhydrides was developed. These two-component systems in aromatic solvents exhibit instantaneous gelation during mixing at room temperature without the requirement of any external stimulus such as heat, sonication, etc. The corresponding alcohols, however, failed to produce gel under similar condition. The structure-property relationship was investigated. The effect of mixing ratio of the two components as well as the effect of solvents on gelation was studied. A detail characterization of the organogels using electron microscopy, FTIR, 1H NMR and X-ray diffraction spectroscopy, differential scanning calorimetry and rheology suggested formation of a hydrogen-bonded complex that induces creation of three dimensional entangled network structures which immobilize the solvent showing macroscopic gelation. The packing of hydrocarbon chains of the amines and π-π stacking interaction in aromatic amines were observed to play a decisive role in altering the thermal and mechanical stability of the organogels. The organogels formed by mixing aromatic amines with the anhydride exhibit exceptional thermal and mechanical stability compared to the aliphatic amines.