Fundamentals of Block Copolymer Directed Assembly

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TECHNICAL SUMMARY:An experimental program is proposed aimed at discovering both new directed assembly methods and their limitations for achieving good translational and orientational order in 2D arrays of block copolymer domains, methods that could ultimately lead to nanopatterns that could be transferred to underlying substrates. Directed self-assembly techniques are proposed for investigation whereby the edges of regions defined by optical and electron beam lithography serve to register and template the order. Emphasis will be placed on understanding the ordering and disordering processes in melts of both single layer and multilayer films of spherical domain block copolymers and their blends with homopolymers in such regions. State-of-the art scanning force microscopy and grazing incidence small angle X-ray diffraction will be used in a complementary fashion to precisely define the order in these layers. Directed self-assembly is also of interest for cylindrical domain block copolymer films with cylinders parallel to the film surface. Here controlling the equilibrium concentration of dislocations and the thermal unbinding of their component disclinations using nearby channel edges is the primary challenge. These experiments will be supplemented with field theoretic numerical simulations of 2D block copolymer ordering in collaboration with Glenn Fredrickson at UCSB. NON-TECHNICAL SUMMARY:Patterning of regular features on the scale of 10 nanometers can enable applications such as ultrahigh density magnetic storage, ultraregular nanoporous filtration membranes and quantum dot arrays. Such patterning is well beyond what is possible directly using light (optical lithography) but this project aims to explore the possibilities of using optical lithography to create larger scale features that can direct the assembly of highly perfect arrays of much smaller block copolymer domains to create the desired patterns. Understanding the causes of imperfections in such arrays and the overall limits of the method are major goals. Undergraduates will be involved in the research both during the academic year and the summer. The research group will continue to host visiting graduate students from foreign countries for periods up to one year to promote international awareness. Major emphasis will be placed on developing graduate student communication and presentation skills, especially in the context of national and even international meetings. Interactions will be developed with nanotechnology groups at various industrial concerns interested in utilizing the results of this research.