Berlin 2005 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 29: POSTER: Polymer physics
CPP 29.21: Poster
Tuesday, March 8, 2005, 16:30–18:30, Poster TU D
SFM characterization of single polymer chains in controlled environments: effect of tip adhesion and chain swelling — •Wei Zhuang1, Christof Ecker1, Paolo Samorí2, and Jürgen P. Rabe1 — 1Department of Physics, Humboldt University Berlin, Newtonstrasse15, 12489 Berlin — 2Instituto per la Sintesi Organica e la Fotoreattività, C.N.R. Bologna, via Gobetti 101, 40129 Bologna, Italy
Isolated slightly hydrophilic chains of poly(isocyanodipeptides) (PIC) adsorbed on mica were studied by Tapping Mode SFM in an atmosphere controlled both with respect to the relative humidity (RH) and the presence of CHCl3 vapor. SFM revealed that the apparent average chain height increases with decreasing RH, leading to the highest value at RH = 0. This is due to both a minimization of the capillary forces between the SFM tip and the hydrophilic substrate surface and a collapse of the side chains in poor solvent. In a saturated CHCl3 vapor atmosphere the chain heights increase up to twice this value, which is close to the polymer diameter measured by powder X-ray diffraction. This indicates that the PIC chains are solvated by CHCl3 molecules, causing the swelling of the single polymers. Additional experiments on an alkylated dendronised polymer revealed that the swelling of the chains occurs also on HOPG.