Periodic Reporting for period 1 - DRC-ECSA (Hierarchical surface patterns from dissolution-reaction-crystallisation mediated evaporation controlled self-assembly (DRC-ECA) and its antimicrobial coating application)
Reporting period: 2015-09-04 to 2017-09-03
In these previous studies, the dispersed non-volatile particles were inert; mechanistically, the pattern formation resulted from a competition between inter-particle forces and capillary and convective solvent flows. It remains little understood how reactive particles may alter evaporation induced patterns, for in situ generated molecular and particulate species can affect the solvent flows and thus the residual pattern.
The overall objectives for this project are:
1) To elucidate a mechanism for the formation of complex patterns from the evaporation of a reactive ZnO nanofluid droplet
2) To study a plethora of physical parameters (such as particle size and morphology, substrate chemistry, evaporation rate, etc.) on the ultimate pattern formation
3) To explore potential functionalities of such surface patterns.
2) Utilizing synchrotron X-ray scattering, we have studied the structural evolution of the surface pattern as a droplet dried. This was complemented by micro-focused GIXS on a pre-dried surface. These results shed further light on the mechanism of the pattern formation.
3) We have explored functionalities of nanotextured surfaces with ZnO patterns, such as anti-reflectance, wettability, and antibacterial efficacy.
Two manuscripts have been submitted, and are currently under review (to Phys. Rev. Materials and Langmuir respectively). 3 further manuscripts are under preparation. The results have been presented at the European Colloids and Interface Society annual conference (2016), the ACS Colloids Symposia (2015, 2016, and 2017). Initial test focusing on the functionalities of these surfaces have been tested, and it has also initiated collaborations with Indian Institute of Science (a Newton PhD placement 6 months).
2) A mechanism has been proposed based on unprecedented observations.
3) Synchrotron scattering has been brought to bear to observe the structural evolution of the surface pattern.
4) Although the full exploitation of such complex patterns is in its infancy, we have demonstrated potential antimicrobial activity of such surfaces, which is relevant to the antimicrobial resistance challenge that faces EU and the world.