Controlled Crumpling of Polymer Thin Films and Nanocomposites

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TECHNICAL SUMMARYThe physical properties of thin polymer films are critical for the development of numerous technologies, ranging from alternative energy sources to ?smart? coatings. In the thin film regime, the size scale of individual molecules is commensurate with the film?s thickness; therefore, the inter-molecular and intra-molecular mechanisms that define a material property are influenced by surface properties. Recent efforts in the polymer scientific community have focused on the impact of confinement on properties such as the glass transition temperature and elastic modulus, but relatively little is known on the impact of geometric confinement on properties related to non-linear deformation. The proposed research will use novel methods to fold and crumple thin polymer films, while quantifying the energy focusing and strain localizing processes involved in these non-linear mechanics. The specific research plan includes three primary efforts: 1) the folding and crumpling of homogenous, thin polymer films; 2) the folding and crumpling of nanostructured polymer films; and 3) the characterization of crumpled surface properties. These efforts will be distinguished from recent research on crumpling by studying films with molecular-scale thickness and combining crumpling mechanics with the properties of pre-patterned substrates to control long-range order in crumpled sheet morphologies. Additionally, the energy focusing processes of folding will be used to assemble nanoscale components, including tailored inorganic nanoparticles. The fundamental knowledge of folding and crumpling gained through this research not only will provide insight into materials properties at molecular length scales, but also will lead to advanced concepts for controlling the morphology and structure of thin polymer films for advanced applications. NON-TECHNICAL SUMMARYThe proposed research is focused on developing novel methods to fold and crumple ultra-thin polymer films, which are only a few molecules thick. The results of this research will have broad impact, from providing new knowledge of how molecular assemblies respond to mechanical stress at the nanometer length scale to developing robust strategies for patterning surfaces in future applications, such as alternative energy source technologies. In addition to the research funded by this program, the research team will introduce an innovative program to involve high school students from diverse backgrounds in the creative aspects of scientific research. This program, the Materials Challenges Competition (MCC), will build upon existing programs that are common in undergraduate engineering disciplines (e.g. the solar powered vehicle competition) to initiate a materials competition among high school teams from the Western Massachusetts region. The implementation of this program will provide opportunities for students and the general public in Western Massachusetts to realize the importance of materials research in answering current technological challenges.