Faculty Candidate TEM Joint Chemistry/Physics Seminar: Optical Materials with a Genome: Polymer-Directed Assembly of Photonic Nanomaterials

A hallmark property of soft matter is the self-assembly of complex structures programmed by interactions among individual components. Biology exploits this programmability to generate remarkable multi-length scale order, and a major goal of soft matter science is to achieve the same kind of assembly in synthetic systems. This talk focuses on novel photonic materials with assembly directed by two classes of polymers. First, we explore how the biopolymer DNA can be used to stabilize few-atom silver clusters with bright fluorescence. DNA not only imparts a unique, rod-like structure on the silver cluster, but the DNA template molecule’s sequence also selects cluster size, tuning emission wavelengths across the visible and near-infrared spectrum. To understand the connection between DNA sequence and Ag-DNA fluorescence wavelength, we combine high-throughput experiments with machine learning strategies, discovering DNA base patterns that correlate to silver clusters of particular sizes and colors. The programmable nature of DNA also enables assembly of silver clusters onto DNA breadboards. In the second portion of the talk, we discuss ongoing work to direct the assembly of photonically active nanoparticles and chromophores using a different class of molecule: block copolymers. Tuning the relative hydrophobicities of polymer blocks and guest molecules or particles dictates assembly of a variety of composite nanostructures. We are using these experimental "knobs" to drive assembly of polymer-hosted nanoparticle and chromophore arrays, with the goal of tuning the spacings and interactions among constituents in the polymer film