Functional Assemblies of Block Copolymers and Polymer-Stabilized Nanoparticles

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The need for advanced materials for photonics, signal processing, biological imaging, and sensing has spurred a growing field of research into tuning material properties at the nano-scale. Block copolymers are synthetic molecules with a remarkable tendency to self-organize into complex colloidal structures of various morphologies, including micelles and vesicles. Metallic and semiconductor nanoparticles are exciting candidates as building blocks for a diverse range of nanostructured materials, due to unique optical and electronic properties that can be tuned as a function of size. For applications in devices and advanced materials, controlling the assembly of nanoparticles and block copolymers in polymeric and nanocomposite materials is a critical challenge. My research program focuses on developing new methods for hierarchical organization of block copolymers and metal and semiconductor nanoparticles in polymer systems, both in thin films and colloids. Our strategy for nanoparticle assembly utilizes hybrid building blocks consisting of nanoparticles encapsulated inside stable polymeric micelles. We use the polymeric brush layer surrounding each nanoparticle to harness various spontaneous structure-forming processes, resulting in controlled nanoparticle self-assembly on multiple length scales. These bottom-up processes can also be coupled to top-down methodologies such as microcontact printing and microfluidics, in order to exercise external handles on size, structure, and complexity. We also seek to understand the collective optical properties of the resulting polymer-nanoparticle assemblies, and how these properties relate to structure on various length scales. Through the combined development of structure control and determination of structure-property relations in polymer-nanoparticle materials, we will establish methodologies for tuning function toward various applications, including photonic circuit elements, chemical and temperature sensors, and multifunctional drug-delivery vehicles.