Collaborative Research: Structure-Mechanics Relationships for Ultra-thin Block Copolymer Films

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PART 1: NON-TECHNICAL SUMMARYThis collaborative project brings together scientists at the University of Massachusetts Amherst and the University of Pennsylvania to gain new understanding of how mechanical properties, like stiffness and strength, change when a polymeric material is made into a film with thickness near the size of an individual molecule. Ultra-thin films, such as the ones studied in this project, are desired to help decrease energy consumption in processes like filtration, as well as in semiconductor manufacturing. However, current materials are unable to provide sufficient strength in these applications. New experimental methods will be combined with molecular simulations to understand how structures in the polymer thin films affect their properties in these highly confined states. Beyond the broad impact related to the development of new fundamental science and materials-design guidelines that will decrease materials waste and increase energy efficiency, this project will provide new opportunities for educating Ph.D. students, undergraduate students, and high-school students through rich, collaborative research experiences involving both experiments and simulations.PART 2: TECHNICAL SUMMARYThis collaborative project will provide new fundamental data and knowledge on the role of block copolymer domain structure in controlling the full mechanical response of ultra-thin polymer films, where film thickness is comparable to or smaller than the domain structure size scale. The proposed approach unites the strengths of advanced simulations and novel experimental methods to test new hypotheses based on the role of position within a confined material on segmental mobility and inter-chain entanglements, and the consequential impact on mechanical properties. Experimentally, a recent mechanical measurement method, called The Uniaxial Tensile Tester for Ultra-Thin films (TUTTUT), will be used to quantify the mechanics of ultra-thin block copolymer films. The experiments will integrate with simulations that use coarse-grained models to predict the molecular response of polymer films, and the simulations will provide a local picture of the changes in the entanglement network and local dynamics as a function of position away from the interfaces in the block copolymer films. Through these efforts, the co-PIs will support the education, training, and inspiration of the next generation of materials scientists and engineers, with a focus toward increased participation of women and traditionally under-represented minorities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.