Regensburg 2010 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 33: Poster: Charge Effects in Soft and Biological Matter
CPP 33.6: Poster
Wednesday, March 24, 2010, 17:30–19:00, Poster C
Dynamics of a tethered polymer chain in an oscillating shear flow: a fluorescence microscopy study — •Maryam Khaksar1,2, Andre Schroder1, Thomas Gisler2, and Carlos Marques1 — 1Institut Charles Sadron, rue du Loess Strasbourg Cedex 2 — 2Universität Konstanz, Fachbereich Physik, D-78457 Konstanz
Advances in fluorescence microscopy of single-molecule DNA and the preparation of well defined surfaces with end-tethered DNA chains has allowed unprecedented scrutiny of the behaviour of single polymer chains near an impenetrable wall in equilibrium as well as out of equilibrium. In this contribution we study the response of single end-tethered DNA molecules to an oscillatory shear flow of frequency ω and shear amplitude γ, using fluorescence microscopy and image processing. At moderate shear amplitude γ the chain behaviour is expected to be controlled by the dimensionless Deborah number De = ω τ, where τ is the longest relaxation time of the polymer chain. At low frequencies De≪ 1 a chain can relax faster than the flow cycle and the deformation is expected to be equivalent to the one of a chain in a stationary flow. At large frequencies De ≫ 1 the chains cannot relax within an oscillation period and one expects the chains to move coherently with the flow. Using fluorescence microscopy we study the dynamic response of end-tethered λ DNA to the flow in the range 0.1 ≪ De ≪ 10, thus exploring not only the small and large Deborah number regimes but also the full crossover region.