It is well-known that mono-dispersed colloidal particles self-assemble into hexagonal close-packed (HCP) structures, under appropriate conditions, which are also known as two-dimensional (2D) colloidal crystals. While various techniques, such as sedimentation, confined convective self-assembly, dip coating, drop casting, evaporative drying, electrophoretic deposition, self-assembly at the gas-liquid interface and Langmuir−Blodgett (LB) technique, inkjet printing etc. has been used for making such arrays, spin coating has its own advantage due to direct compatibility with microelectronic processing, pattern uniformity and requirement of very small amount of colloidal dispersion. We first show that monolayer colloidal crystal formation by spin coating is possible only in a narrow parametric window involving spin speed, substrate wettability, particle size, and substrate pattern geometry, in case a topographically patterned substrate is used for template guided assembly. Subsequently, I will highlight a facile colloidal transfer printing method that relies on UVO mediated degradation of a sacrificial PMMA thin film. The method is capable of transferring both hexagonal closed pack (HCP) and template guided non-HCP arrays of inorganic or polymeric colloids onto any hydrophobic or hydrophilic target surface, which can be smooth, rough, or even curved. The method does not require any surface modification of the target substrate or any medium to facilitate the transfer. Finally, I will show that in certain cases the transferred particle array can significantly enhance the anti-reflection property of the target surface and can also be used as a template for growing patterned Zinc Oxide Nano Rod array which exhibit Self Cleaning property.
M. Banik and R. Mukherjee, ACS Omega, 3, 13422, 2018.
M. Banik, N. Bhandaru and R. Mukherjee, Chem Comm. 54, 3484, 2018
5:00 PM–7:00 PM Apr 23, 2019 (US - Arizona)
PCC North, 300 Level, Exhibit Hall C-E