Delicate Junction Meniscus Manipulation for Three-Dimensional Nanostructures Using Partially Molten Interfaces: Implications for Plasmonic Sensing

We introduce a straightforward strategy for the creation of a three-dimensional nanostructure by manipulating the interface junction meniscus. This approach relies on delicate controls of the liquid meniscus between a nanosphere array template and a partially molten polymer surface. Solution composition and drying condition are determined to be feature-dominating factors, and the effects of these parameters are thoroughly investigated. As the polymer-dissolving surfactant and polystyrene nanosphere mixture solution evaporates, the hexagonally close-packed self-assembled nanospheres precisely localize the interface liquid meniscus. Movements of meniscus and accumulation of dissolved polymers under controlled relative humidity and solution composition produce various nanoscale polymer structures, including rings, targets, and holes. Models for the formation of nanostructures are constructed by monitoring the relationship between experimental parameters and the resulting surface features. Single rings, nanotargets, and nanoholes are related to the local surfactant concentration underneath the template nanospheres, while the formation of double rings is related to the ratio between polymer advection flux and solute diffusion flux in the meniscus. In addition to the aforementioned geometry regulations, the affinity of the solution toward the polymer surface also affects feature dimensions and can be utilized to influence the final structure location and resolution. Delicate controls over the meniscus-guided surface nanostructures are therefore achieved through fine-tuning of the surfactant-induced partially molten polymer surface.