Ultra Thin Layers
Scientists from the Max Planck Institute for Polymer Research in Mainz, in collaboration with Professor Schouten's research group at the Rijksuniversiteit Groningen, have for the first time studied the electromechanical properties of polypeptides grown directly on a flat surface. One of the challenges in supramolecular chemistry is the fabrication of ultrathin layers with a stable polar arrangement. Materials with such properties are required for the construction of nanometer-sized piezoelectric and pyroelectric circuits as well as for electro-optical applications. The scientists from Mainz and Groningen "grow" monomolecular films of the helical polypeptide poly-gamma-benzyl-L-glutamate (PBLG) with a thickness of 15 nanometers directly on a flat aluminum surface. Infrared spectra showed that the alpha-helical polypeptides were arranged upright on the surface (Science 2 January 1998).
The polarization of the PBLG could be examined more closely with the help of a special measuring instrument, the Normanski optical interferometer. It turned out to be comparable to that of conventional ferroelectric materials. This result indicates that as the polymerization starts from the surface, the helical chains are forced into a polar arrangement. Although these piezoelectrically active layers have a lower piezoelectric coefficient than most commercial materials, they can be grown on a wide range of electrodes without the need for subsequent alignment.
The experiments of the two working groups show for the first time that the theoretical predictions of how individual polypeptides are present in their helical form along the helical axis correspond to reality.
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