Fracture in Nanostructured Polymeric Materials

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TECHNICAL SUMMARY:This research program will explore the connections between the molecular architecture of block copolymers and the mechanical properties of the resulting nanostructured plastics. Mutiblock copolymers will be synthesized using controlled polymerization techniques augmented by chemical modification such as catalytic hydrogenation. These compounds will be investigated in undiluted and blended forms. Self-assembly into ordered and disordered microphase separated materials will be characterized by a compliment of experimental techniques such as small-angle X-ray and neutron scattering, electron microscopy, dynamic mechanical spectroscopy, and birefringence analysis. Tensile and impact mechanical properties will be evaluated and correlated with the morphological structure and molecular architecture. Selected block copolymer and blend specimens will be partially voided by chemical etching or selective solvent extraction resulting in nanoporous monoliths that will be subjected to fracture analysis. New strategies will be developed to toughen these intrinsically fragile porous compounds, through a combination of multiblock copolymer design, strategic placement of rubbery, glassy, and semicrystalline blocks within the matrix material, and blending of multiblock copolymers with synergistic molecular architectures.NON-TECHNICAL SUMMARY:Perhaps no other class of material properties has a greater impact on the utilization of plastics than mechanical robustness. This research program will explore the connections between the molecular structure of polymer molecules, produced by controlled synthetic chemistry methods, and the fracture behavior of the resulting materials. This work will impact the application of new plastics in commercially important products ranging from optical media such as laptop computer screen, new types of membranes that may find uses in fuel cells and batteries, and inexpensive and light plastics used extensively in the automotive industry. This program affords outstanding opportunities to enthuse and inform students at all levels of education in science and engineering through interactive programs at the University, local schools, and regional museums.