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    Surface Morphology and Molecular Organization of Lignins in Langmuir-Blodgett Films

    Year: 2002

    Journal: Langmuir 2002, 18, 6593-6596, 20111221

    Authors: Daniel Pasquini, D. T. Balogh, P. A. Antunes, C. J. L. Constantino, A. A. S. Curvelo, R. F. Aroca, and O. N. Oliveira, Jr.

    Organizations: Instituto de Fisica de Sao Carlos, Universidade de Sao Paulo, CP 369, 13560-970 Sao Carlos, SP, Brazil, Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, CP 780, 13560-970, Sao Carlos, SP, Brazil, Faculdade de Ciancias e Tecnologia, Universidade Estadual Paulista, CP 467, 19060-900 Presidente Prudente, SP, Brazil, and Materials and Surface Science Group, School of Physical Science, University of Windsor, N9B 3P4 Windsor, Ontario, Canada

    Atomic force microscopy(AFM)and Fourier transform infrared spectroscopy (FTIR) are used to investigate molecular organization in Langmuir-Blodgett (LB) films of two kinds of lignins. The lignins were extracted from sugar cane bagasse using distinct extraction processes and are referred to here as ethanol lignin (EL) and saccharification lignin (SAC). AFM images show that LB films from EL have a flat surface in comparison with those from SAC. For the latter, ellipsoidal aggregates are seen oriented perpendicularly to the substrate. This result is confirmed by a combination of transmission and reflection FTIR measurements, which also point to lignin aggregates preferentially oriented perpendicularly to the substrate. For LB films from EL, on the other hand, aggregates are preferentially oriented parallel to the substrate, again consistent with the flat surface observed in AFM data. The vibrational spectroscopy data for cast films from both lignins show random molecular organization, as one should expect.