Rheological Signature of a Thermally-Gelling Nanoemulsion

We report the rheological behavior of a new thermoresponsive oil-in-water nanoemulsion system. The nanoemulsion undergo a transition to a gel at elevated temperature. The gelation mechanism is entirely different from previous reports and nanoemulsion droplets play a major role in thermoresponsive behavior. The formulation contains FDA approved amphiphilic triblock copolymer as gelling agents. Nanoemulsions were also prepared using a low-energy process. The thermogelling formulation exhibits unique rheological behaviors. The power-law shear thinning behavior at sol and gel states were observed. Yielding behavior of the nanoemulsion gels was characterized using large amplitude oscillatory shear (LAOS) experiments. These gels display strain-softening behavior under application of large shear-deformation prior to failure of the material. The material turn back to the initial state simultaneously after cessation of applied high shear stress/strain.