Gradient Films from Shape Memory Nanofoams for Unattended Sensing
Anna Paola Soliani, Yuriy Galabura, Bogdan Zdyrko, Spencer Novak, David Musgraves, Kathleen Richards
Materials Science and Engineering (College of Engineering and Science)
The current research focuses primarily on the development of polymeric nanostructured foams that can selectively sense the immediate chemical environment and retain memory of the specific exposure event(s). These functional polymer materials show a strong interplay between the tailored structure of the system and the functionality of the material. Specifically, 50-300 nm thick polymeric nanofoams with a gradient chemical composition along the sample have been obtained. The nanofoams possess the behavior of a shape memory material. At room temperature, the nanofoams are thermodynamically unstable, but kinetically trapped in a porous shape. Upon exposure to various analytes, the polymeric coatings locally and irreversibly change their internal structure at the nanolevel. Active changes in the optical characteristics of the nanofoam coating can be used to monitor the permanent alteration in the film nanostructure. Consequently, these nanofoams will be efficient and highly sensitive coatings for diverse evanescent waveguide- and resonator-based optical monitoring systems. It is expected they will have a broad usage in unattended sensing applications.