Synthetic chemists have long striven to mimic nature's ability to construct large and complex aggregates and molecular machinery that perform critical functions in the body by spontaneous association of small, well-defined building blocks such as proteins. Inspired by this biological analogy, this research project aims to develop a new class of fully synthetic polymer molecules with brush-like architecture that provides three-dimensional control over the shape of the molecules and their interactions to guide the biomimetic molecular organization. Such highly tunable molecular building blocks will be prepared by newly developed synthetic chemistry methods and studied by a variety of techniques for the formation of advanced materials. These materials will be relevant to water filtration membranes, uniform biomimetic vesicles, and lightweight nanocomposites, for a variety of energy and health related applications. The planned research activities will advance the current understanding of molecular assembly, allow for unprecedented levels of biomimicry, and offer potentially new avenues for the fabrication of high-value nanomaterials. The scientific aspects of the proposed research program will be integrated with broader outreach and educational initiatives aimed at improving science/technology/engineering/mathematics (STEM) education and developing a competitive STEM workforce through teacher professional development and graduate and undergraduate student training.
The research to be conducted under this project aims to develop new modes of polymer assembly directed by molecular architecture. Comb-like macromolecules with a persistent shape and spatial control over compositional profile and intermolecular interactions will be developed by introducing three new structural motifs: bottlebrush architecture with a gradient compositional taper along the backbone, quadruple hydrogen bonding functionalities on bottlebrush periphery, and highly associating polyimide brushes. A combination of different intermolecular interactions spatially guided by the bottlebrush architecture will be used to drive the assembly of polymeric building blocks into highly ordered nanomaterials. Three specific objectives will be pursued: (1) synthesis and melt self-assembly of gradient bottlebrush copolymers, (2) programmed biomimetic assembly of amphiphilic bottlebrush copolymers with strategically directed hydrogen bonding interactions into highly uniform porous aggregates, and (3) synthesis of polyimide nanoparticles and nanofibers by controlled anisotropic aggregation of core-shell bottlebrush copolymers. The successful outcome of this research program will provide access to a new molecular architecture, design principles to control the directionality of intermolecular interactions and molecular orientation within the self-assembled nanostructures, and the potential fabrication of previously unattainable materials with a wide range of properties and applications.
