Catalysis of Microstructure Evolution in Block Copolymer Blend Materials Through Dynamic Modulation of Filler/Matrix Interactions

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NON-TECHNICAL SUMMARY: Block copolymers are materials that are capable of self-organizing into a hierarchy of functional nanostructures that are of technological relevance in applications ranging from polymer membranes for next-generation lithium ion batteries to high-performance polymer photovoltaics. The goal of this project is to develop processes to control the formation of defects in these nanostructures, a key requirement for the future technological exploitation of block copolymer based materials. The ultimate goal is to establish procedures that will allow the efficient and economically viable fabrication of block copolymer materials with precisely controlled nanostructure and properties. The program will enhance the teaching of two polymer classes and provide training for one graduate and several undergraduate researchers in the critical area of polymer and nanoscale materials. Ongoing collaborations with educators at Florida A&M University as well as Carnegie Mellon will be leveraged to support the participation of minority students and to engage high school students in materials engineering. Finally, a novel educational interface will be developed for 'hands-on' exploration of materials physics concepts as a means to engage and attract middle and high school students to the study of science and engineering.TECHNICAL SUMMARY: The objective of this research program is to understand the implications of filler-matrix interactions on the microstructure evolution in bulk block copolymers and to test the hypothesis that the dynamic modulation of filler-matrix interactions provides a means to increase the rate of grain coarsening. In a first part the project will be focused on the synthesis of a range of homopolymer and polymer-grafted nanoparticle model systems that will facilitate the elucidation of the effect of filler-matrix interactions on the microstructure evolution process in block copolymer blend materials. In a second part, the project will establish the coarsening kinetics and evolution of grain boundary structures in block copolymer/homopolymer blend systems in which the homopolymer favorably interacts with the host copolymer domain. A parallel series of corresponding block copolymer/nanoparticle blend systems will be pursued to identify the role of filler-matrix interaction on the segregation of fillers within boundary regions. In a third part, the program will explore the effect of temperature-cycling to dynamically (and reversibly) 'switch' the interaction between filler and copolymer host domain from 'athermal' to 'miscible'. The objective is to test whether the dynamic modulation of filler-matrix interactions provides a means to energetically destabilize grain boundary defects and hence raise the driving pressure for grain growth. The research plan will be enhanced by collaboration with expert groups in the areas of polymer synthesis and simulation who will provide access to model material systems and support the interpretation of data.