Acquisition of an Electron Microscope (Materials Research)

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A transmission electron microscope for use in investigations of complex fluid and polymer systems will be acquired. Novel freeze-fracture techniques used will directly examine polyacrylamide gels, rod-coil transitions of polydiacetylene solutions, and surfactant-oil-water microemulsions using electron microscopy. Rapid freezing of these systems can preserve the microstructure without artifact. The solidified fluid is fractured and coated with layers of platinum and carbon to replicate the fracture surfaces. These replicas are then examined in the electron microscope with molecular resolution. The replicas can also be examined with the scanning tunneling microscope to assess three dimensional contours with high resolu1tion. Individual polymer chains can be visualized with unprecedented resolution and the distribution of interstitial fluid in gels can be measured. For the first time, direct feedback about the influence of external perturbations on the gel structure is possible. The three dimensional structure of mid- range microemulsions consisting of equal volumes of oil and water cosolubilized by surfactant can also be examined with molecular resolution. Solution cast films of conducting polymer composites can be examined to determine the nature of the composite and the morphology of the conducting fraction. Biological and other non-conducting materials can be imaged simultaneously with scanning tunneling and transmission electron microscopy.