Self-assembly Mediated Fabrication of Novel Nanostructures

Speaker: Meneka Banik (Technion - Israel Institute of Technology)

Date and time


Self-assembled 2D colloidal crystals, comprising monolayers of microspheres or nanospheres, are gaining significant attention for their applications in photonic crystals, sensing materials, etch masks, coatings, and more. Among fabrication methods, spin coating stands out for its efficiency, cost-effectiveness, and control over large-area ordered arrays. Through rigorous experimentation, we optimized parameters to achieve perfect hexagonal close-packed (HCP) and non-HCP arrays on both flat and patterned substrates. To enhance versatility, we developed a UV-based colloidal transfer printing technique capable of transferring particles onto diverse surfaces, including rough and non-planar ones. Leveraging this technique, we transferred monolayer HCP arrays onto zinc oxide (ZnO) surfaces, facilitating the growth of colloidal template-assisted ZnO nanorods (NRs), resulting in superhydrophobic and self-cleaning properties. Additionally, using UV-induced degradation of a sacrificial PMMA layer, we transferred Janus particles into a liquid medium, enabling the investigation of Gold-Polystyrene Janus particle assembly on various substrates.

Soft lithography techniques are prominent in replicating surface features in polymer films at the mesoscale. While past efforts focused on topographic variations, our work demonstrates the use of soft lithography on block copolymer films. We show that the selective affinity of one polymer block to the stamping material induces chemical variations corresponding to surface topography. Comprehensive surface and structural analyses reveal the three-dimensional architecture of the patterned films, highlighting domain reorganization within the block copolymer film alongside topography formation. These structures facilitate the directed assembly of gold nanoparticles into hierarchical arrangements. Our integrated nanofabrication/self-assembly approach enables precise assembly of two distinct metallic nanoparticle types into separate configurations, providing complete control over nanoparticle positioning.