CAREER: Directed Self-Assembly of Block Copolymers by High Magnetic Fields

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).TECHNICAL SUMMARY:This proposal outlines a 5-year plan centered on the directed self-assembly of block copolymers (BCPs) using magnetic fields, and the use of aligned materials as templates for the synthesis of semiconducting nanowires. Today?s materials science is predicated on the ability to control the structure of matter on multiple length scales. The history of metallurgy and ceramic science illustrate the evolution of this capability through to today?s bulk and thin film single crystal growth processes. The trajectory in polymer science is nascent by comparison - surprisingly, practical and scalable methods for processing BCPs with controlled grain size and orientation are still lacking. The absence of these capabilities hampers the development of new technologies that harness the self-assembly of functional BCPs and nanocomposites such as in non-linear optical materials, membranes and photovoltaics. This proposal directly addresses the above mentioned gap. It takes a novel approach to directed self-assembly via the use of high magnetic fields using a dedicated instrument to conduct critical in-situ studies of alignment dynamics in a hierarchically ordered polymer system. It entails rational design of materials based on tailoring interfaces between self-assembled microdomains and pursues the synthesis of perpendicularly aligned nanowires using large-area thin film templates as a step towards the realization of ideal photovoltaic geometries. The objectives are: (1) Rational design, synthesis and characterization of model liquid crystalline (LC) BCPs for field alignment; (2) Quantitative studies of temperature and field-dependent alignment of materials via in-situ scattering and ex-situ microscopy; (3) Synthesis of compound semiconductors CdS and ZnS within macroscopically field-aligned BCP films. NON-TECHNICAL SUMMARY:The proposed work will contribute to emerging technology solutions in fields such as photovoltaics, non-linear optics and membranes. It specifically takes aim at the production of semiconducting materials which can be used for next generation solar cells. The project will include interactions with a national lab, the National High Magnetic Field Lab, via visits by students and the PI. Mentoring student researchers is an important component of this proposal. In particular, active participation of all supported students in the community of science locally, regionally and nationally will be an integral part of their training and will strengthen their desire for lifelong learning. The proposed work forms the basis for a new teaching and outreach thrust by the PI centered on polymer materials science. A new course on Polymer Physics which includes a lab module will continue to be offered by the PI. The PI will engage in outreach targeting middle and high school students at the community level, and under-represented students at Yale. Through partnership with the New Haven Science Fair, a new summer research program for local high school science teachers has been proposed. The impacts overall are: (1) Development of fundamental science with applications in solar cells; (2) Education of undergraduate and graduate students in materials science and polymer science; (3) Development of new materials/polymer science curriculum; (4) Improved materials science training of middle-high school students and teachers; (5) Recruitment and mentoring of underrepresented groups at the undergraduate and graduate level; (6) Strong integration of new researchers into their science community at all levels.