SGER: Spontaneous Formation of Ordered Structures from a Capillary-Held Solution

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National Science Foundation - Division of Chemical &Transport Systems Particulate & Multiphase Processes Program (1415)Proposal Number: 0730611 Principal Investigator: Lin, Zhiqun Affiliation: Iowa State University Proposal Title: SGER: Spontaneous Formation of Ordered Structures from a Capillary-Held solution Intellectual MeritDynamic self-assembly of nonvolatile solutes through irreversible solvent evaporation of a drop from a solid substrate is widely recognized as a nonlithography route for the spontaneous formation of complex, large-scale structures. The flow instabilities within the evaporating droplet, however, often result in nonequilibrium and irregular dissipative structures, e.g., convection patterns, fingering instabilities, and so on. Therefore, to fully utilize evaporation as a simple tool for achieving well-ordered 2D structures, it requires delicate control over flow instabilities and evaporation process. The aim of the proposed research is to explore a simple, one-step method for producing micro- and nanostructured materials in a precisely controllable manner, dispensing with the need for lithography techniques and external fields. Two specific objectives are proposed. First, creating ordered structures with unprecedented regularity by controlling the flow of an evaporating droplet containing nonvolatile solutes in restricted geometries (i.e., a capillary-held solution). Second, understanding the mechanism of the formation of intriguing structures. We intend to produce highly regular structures with homopolymers. The intellectual merit of the proposed research is manifested in the innovative studies of exploiting restricted geometries as unique environments for controlling the flow within an evaporating droplet, which, in turn, regulate the ordered structure formation in one-step with unprecedented regularity for use in optics, electronics, tissue engineering, and nanotechnology. Broader ImpactsThe broader impacts of the proposed work include stronger nanoscience education at the graduate and undergraduate levels. Female undergraduate students will be recruited for summer nanomaterials research, thus strengthening the involvement of an underrepresented groups in the project. Knowledge generated in this project may lead to the creation of optical, microelectronic, and optoelectronic devices that exhibit novel functions due to the periodic arrangement of polymeric building blocks, thus transitioning fundamental scientific discoveries into useful technologies that benefit society.