(3bj) Optical Nanoscopy Will Enable the Creation of New Materials

Much of the success in the design of material properties is due to the control of the structure of matter. Simultaneously, contemporary challenges in Energy, Health and Computing demand novel materials with previously unattainable, multifunctional or maximized properties. My research experience and interests broadly reflect the importance of structure in the creation of new materials. My specific interests lie in the study of three dimensional (3D) nanoscale morphology. In particular, the nascent ability of Optical Nanoscopy to image deep within the bulk of nanostructured materials will be exploited. The research dream is to “dial-in” material properties by controlling 3D morphology on the nanoscale with exquisite precision. Soft Matter, Optics and Unconventional Lithography are the primary themes of my work. Short term projects in self assembled polymers, multifunctional materials and transformation optics that target immediate needs in Energy, Health and Computing have been identified.

Optical Nanoscopy

This poster presents far-field optical nanoscopy as a viable candidate for the 3D imaging of polymeric nanostructures. Non-invasive imaging with nanometric resolution that collects local, dynamic, molecular specific and 3D structural information can shorten the process of establishing structure–property relationships. Conventionally, real space imaging (as opposed to scattering based methods) at the nanoscale has been performed with electron or scanning probe microscopes. However, these techniques do not provide easy access to truly 3D information, either yielding 2D projections of thin sections or being restricted to near surface morphologies. Although fluorescence microscopy meets the demands of in situ 3D imaging, the width of the focal spot, and thus the resultant resolution, was till recently limited by diffraction of the light used. This barrier has now been circumvented by exploiting the on–off switching of the fluorescence ability of markers.

Stimulated emission depletion (STED) microscopy, which produces tiny focal spots by deactivating molecules on the outer rim of the diffraction-limited spot is a powerful implementation of this approach. The singular strengths of fluorescence microscopy that are retained by STED are particularly relevant to polymeric nanostructures. This includes the ability to non-invasively image within the volume of a material, capture dynamic phenomena, and the ease and specificity with which target phases can be tagged. Specific examples that would be challenging to image with contemporary techniques, such as the non-destructive nanoscale imaging of colloidal crystals and block copolymers that consist of 3D data stacks; the recording of assembling colloidal 2D nanostructures at speeds as high as 200 Hz; the in situ imaging of solvent swollen block copolymers and the development of a flexible microdomain specific tagging technique are presented. The ability of STED to "see" within polymers with nanometric resolution highlights the enormous potential of subdiffraction far-field fluorescence microscopy for the polymer sciences.