Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 35: Poster: Micro- and Nanofluidics
CPP 35.7: Poster
Mittwoch, 16. März 2011, 17:00–19:00, P2
Dynamic Wetting of Polyisoprene Melts with Different End Groups — •Elmar Bonaccurso1, Chuanjun Liu1,2, Mordechai Sokuler1,2, Günter Auernhammer2, and Hans-Jürgen Butt2 — 1Center of Smart Interfaces, TU-Darmstadt, Germany — 2Max Planck Institute for Polymer Research, Mainz, Germany
We investigate the spreading of drops of polyisoprene melts with different end groups, methyl (PI-CH3), hydroxyl (PI-OH), and carboxyl (PI-COOH), on hydrophilic silicon surfaces. The three polymers have the same backbone and contour length. The only difference lies in the end group. We show its influence on the dynamics of wetting. Our experimental results indicate, e.g., that spreading of PI-OH and PI-COOH is slowed down as compared to PI-CH3.
Lower contact angles are attained if the end groups strongly bind to the solid surface. Hence, the wetting capability of the polymer melt could be improved by non-covalent interfacial interactions via its end groups. The hydrodynamic model[1] applied to our measurements gives a good fit to the experimental data, but does not yield reasonable values for the apparent slip length. This suggests that additional dissipative processes are at work within the three-phase zone, which may not be omitted from the overall description. Molecular Kinetic Theory[2] (MKT) analysis indicates that strong binding of molecules to surface leads to longer relaxation times, thus to a slower spreading process [3].
[1] O.V. Voinov, J. Colloid Interface Sci. 226, 22 (2000) [2] T.D. Blake, J. M. Haynes, J. Colloid Interface Sci. 30, 421 (1969). [3] C.J. Liu et al., Langmuir, 26, 2544 (2010)