(180ar) A Study of Dynamically Tuned Surface Properties in Lithographically-Patterned Membranes

Here we explore the effect of mechanical strain on the surface properties of lithographically patterned nanocomposite thin film membranes by probing their wetting behaviors. The nanofillers in the nanocomposite thin films provide structural integrity yet retain the flexibility afforded by the polymeric matrix. These membranes are lithographically patterned such that the original planar geometry transforms into a three-dimensional one by a simple external stimulus (i.e. a uniaxial strain) at the predefined regions. We experimentally demonstrate that the strain-induced morphological change can be exploited to control surface properties by monitoring the wetting behavior of a droplet on the surface of the film. We show that the contact angle can be dynamically tuned and surface tension gradient induced. Such a dynamically tunable surface can be generalized to apply to various material systems, serve as a novel strategy to alter interfacial interactions, and offer possibilities in controlled droplet morphology, directed flow, and switchable surfaces.