CAREER: Unique Nanostructured Materials from Molecularly Engineered Bottlebrush Copolymers

TECHNICAL SUMMARY The goal of this project is to utilize densely grafted copolymers with bottlebrush architecture for the fabrication of nanoporous objects and nanostructured materials with exact structural and functional control. The research supported by this CAREER grant will focus on (1) the synthesis of multi-component bottlebrush copolymers, (2) molecular templating of shape-persistent bottlebrush macromolecules, and (3) melt-phase self-assembly of bottlebrush block copolymers. Advanced bottlebrush copolymers with tailored chemical framework will be synthesized by a combination of living radical and ring-opening polymerization techniques. Multi-component bottlebrush copolymers will be converted to standalone open-end tubular nanoobjects with well-defined structural parameters (length, diameter and pore size) and functional composition. The bottlebrush macromolecular scaffold will enable the preparation of structures otherwise unattainable under thermodynamic control of self-assembly. The molecular design will be expanded to prepare radially amphiphilic nanotubes and stimuli-responsive molecular cages. The prepared nanostructures will serve as versatile building blocks for the fabrication of nanodevices and as encapsulating agents in drug delivery applications. Melt-phase self-assembly of diblock bottlebrush copolymers will be investigated for the preparation of periodic nanostructured materials with large domain spacings and hierarchical systems. An array of characterization techniques, including ultra-small X-ray scattering and transmission electron microscopy, will be utilized to study melt phase behavior of these macromolecules. This research will help to establish the relationships between the shape of constituent bottlebrush copolymers and their packing tendencies, which is an essential prerequisite for the fabrication of tailored materials on their basis. Core-shell and other advanced bottlebrush copolymers will allow for the fabrication of complex network and composite structures, which will be aimed for photonics and ultrafiltration applications. NON-TECHNICAL SUMMARY The promise of nanotechnology cannot be realized without the availability of tailored materials that are precisely structured at the nanometer length scale. The research described in this proposal will provide access to new polymeric nanomaterials that are not attainable by any other methods and that will be of potential utility in a wide array of applications, such as nanodevices and nanoelectronics, drug delivery, photonics and communications, and water purification. The research program supported by this CAREER grant will simultaneously integrate educational initiatives to promote polymer and nanotechnology education in the Buffalo area. Nanotechnology workshops will be organized for middle and high school teachers to provide them with professional development opportunities and content gain. The aim is to increase public awareness and appreciation of polymeric materials and their impact on nanotechnology and other advanced applications, and promote the use of polymers to enhance science and technology education in general. The partnership with Buffalo Public Schools, the poorest urban school district in New York State, will maximize the impact on underrepresented minorities and low-income students. Polymer education at the undergraduate level will be promoted by providing research opportunities for undergraduate students, and by organizing freshman seminar series.