Unusual “coffee rings”: Hierarchical surface patterns from evaporation of a reactive ZnO nanofluid sessile drop

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)


Drying of a particle laden droplet is widespread in everyday life and industrial processes, and can lead to a plethora of residual patterns, most notably the coffee ring. Its formation mechanism was firstelucidated around two decades ago. The vast academic interest it stimulated continues to thrive today, and it is also directly relevant to producing functional devices and nanomaterials. However, the dispersed particles are inert in most studies. In this work, I present studies on formation of complicated surface structures under conditions far from equilibrium via rapid evaporation of a sessile drop containing reactive ZnO nanoparticles in a mechanism that is very different from that observed in the coffee ring effect.
Date of Award24 Jul 2019
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorWuge H Briscoe (Supervisor) & Annela M Seddon (Supervisor)


  • Evaporation induced self-assembly
  • Coffee ring effect
  • Bénard-Marangoni instabilities
  • Fractal dimension analysis
  • Reactive nanofluids
  • Zinc oxide
  • Crystallinity
  • X-ray scattering

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