Arrest of morphological transformation during evaporation-induced self-assembly of mixed colloids in micrometric droplets by charge tuning

Abstract

Self-assembled grains of mixed colloids have been synthesized using evaporation induced self-assembly (EISA) by spray drying. We demonstrate using electron microscopy and small-angle neutron scattering experiments that buckling driven sphere to deformed-doughnut like morphological transformation in such a process can be arrested by proper tuning of the surface charge on the colloidal components. The buckling amplitude diminishes with a reduction in stabilization force between the colloidal particles. It is established that such arrest of morphological transformation is related to an effective exposure of the surface of softer component at gas–liquid interface. Scattering experiments confirm relatively more compact structure of the non-buckled grains compared to that of the buckled grains. A plausible mechanism regarding the arrest of morphological transformation by surface charge tuning is illustrated.