The latest NSF Workshop report on Polymersconcluded that �recent advances in polymer syntheses leading to elaborateand precise architectures require accompanying advances inmicrostructural characterization beyond currently available techniques, whichare collectively inadequate�.  Observationof the birefringence that is produced by application of a strong electric fieldto dilute solutions of poly-mers dissolved in non-polar solvents with lowdielectric constants, ie., electrical birefringence or the Kerr-Effect, canprovide a means to more fully characterize polymer microstructures than can beachieved with the currently most sensitive technique, NMR spectroscopy.  Largely a consequence of the fact that themolar Kerr constants,  mKs, of small molecules,including monomers,  range over more thanfour orders of magnitude, and may be either positive or negative in sign, the mKs of polymers can be moresensitive to their microstructures than are their NMR spectra. Additionally, becausea polymer's  mK is a �macroscopic� property characteristic of itsentire chain, any microstructural element that alters its overallpolarizability tensor or changes themagnitude and/or orientation of  itsoverall dipole moment vector with respect to the direction of  its maximum polarizability will effect its mK. Unlike NMR or other spectro-scopies dependent onlyupon local polymer microstructures, the macroscopic positions/locations ofmicrostructures along the polymer chain (middle vs. end) may also effect  itsmK, so Kerr-Effect observationsmay, as well, permit identification of the positions/locations of  �elaborate and precise polymer architectures�.

The Kerr-effect as a means to characterize and locate long-range microstructures in polymers

242nd National Meeting (2011)

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