Berlin 2001 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 19: Poster: New Methods, Thin Polymer Films, Monolayers
CPP 19.29: Poster
Thursday, April 5, 2001, 12:30–15:00, AT1
Reorientation of Nematic Liquid Crystals by a Novel Azobenzene Polyamic Acid — •Yun Zong1, Ulrike Hees1, Jürgen Rühe1,2, and Wolfgang Knoll1 — 1Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz — 2Institute of Microtechnology(IMTEK), University of Freiburg, Georges-Koehleralle 103, 79110 Freiburg
Novel azobenzene functionalized polyamic acid molecules were synthesized and characterized. Owing to the introduction of bulky side groups which reduced the conjugation in the polymer, the polyamic acid exhibits good solubility in many different solvents, thus allowing for the molecular weight (MW) determination by GPC in either THF or DMF. The amphiphilic character of the polymer can be used to readily fabricate multilayer structures with more than 400 layers by the vertical dipping Langmuir-Blodgett-Kuhn (LBK) technique with very good transfer behavior. The thickness dependence of the multilayers on different substrates was studied by either small angle incident X-ray reflectivity or surface plasmon resonance spectroscopy. The results of X-ray reflectivity measurement suggest a very regular internal structure of Y-Type LBK multilayers with a repeat unit of 2.7 to 3.5nm (the value depends on the dipping speed and corresponds to the thickness of one bilayer ) giving rise to a much pronounced Bragg Peak. The photoisomerization of azo-moieties and the reorientation of nematic liquid crystals are investigated.