Dispersion of hydrophobic colloids in water or hydrophilic colloids in hydrophobic solvent is unstable and readily undergoes irreversible aggregation. A stable dispersion of colloids in ‘phobic’ environment are known to require interfacial chemical camouflages that imparts particle-solvent affinity through polarity matching with the environment. Such provides steric and electrostatic effects that renders increase in the inter-particle repulsive potential. Generating additional repulsive effects by a physical canopy would overcome the limitations imposed by the traditional chemical modification and also would preserve the pristine colloidal properties and functionalities In this research, we show that the ‘hedgehog’ particles with arrays of high aspect ratio ZnO nanowires coated on a surface of microsphere exhibit stable dispersion in both ‘philic’ and ‘phobic’ media. Verifying the experimental findings through EDLVO based calculations, high surface corrugation leads to limited contact area and increased minimum interaction distance that drastically reduces the attractive potential. Furthermore, solvent-ionization at the air-water interfaces of trapped air-pockets in the nano-topography provides extra repulsive potential in the case of aqueous dispersion of hydrophobic HPs. Low ionic strength provides longer-range repulsive potential in the case of hydrophilic HPs in non-polar organic media. The findings could lead to reduction in the use of the volatile organic compound in a wide spectrum of industries ranging from pharmaceutical to paint, enable new strategies for exotic colloidal behavior and self-assembly, and exhibit unexplored or enhanced physicochemcial properties ranging from photophysics to catalysis.

Anomalous dispersion of 'hedgehog' particles

251st National Meeting (2016)

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