Many soft materials, such as block copolymers and micelles, are characterized by a tunable organization that can be exploited for formation of nanostructures. In this work, drying patterns, formed when nanoparticle solutions are spin coated on ultrathin films of the block copolymer poly[styrene-b-ethylenepropylene] (PS-PEP), are investigated as a function of the film's organization. Prior to particle deposition, thermal annealing was used to adjust the polymer film organization between a layer of PS-PEP micelles (no annealing) and a bilayer with a uniform PEP 'polymer brush' layer on top of an underlying layer of PS (extensive annealing). For intermediately annealed films, ring-shaped drying patterns consisting of as few as 5 or as many as 30 nanoparticles are observed. The nanorings are polydisperse with a diameter between 15 and 50 nm, and cover macroscopic surface areas of the film. It is suggested that these rings form as a consequence of inhomogeneous drying of particle solutions due to heterogeneities in the film structure, as deposition of nanoparticles on extensively annealed, uniform films did not produce rings.
ASJC Scopus subject areas
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering
- Electrical and Electronic Engineering