la702352x_si_002.pdf (394.56 kB)
Single-Molecule Measurement of the Strength of a Siloxane Bond†
journal contribution
posted on 2008-02-19, 00:00 authored by Peter Schwaderer, Enno Funk, Frank Achenbach, Johann Weis, Christoph Bräuchle, Jens MichaelisIncreasing the mechanical stability of artificial polymer materials is an important task in materials science, and for
this a profound knowledge of the critical mechanoelastic properties of its constituents is vital. Here, we use AFM-based
single-molecule force spectroscopy measurements to characterize the rupture of a single silicon−oxygen bond in the
backbone of polydimethylsiloxane as well as the force−extension behavior of this polymer. PDMS is not only a
polymer used in a large variety of products but also an important model system for highly flexible polymers. In our
experiments, we probe the entire relevant force range from low forces dominated by entropy up to the rupture of the
covalent Si−O bonds in the polymer backbone at high forces. The resulting rupture-force histograms are investigated
with microscopic models of bond rupture under load and are compared to density functional theory calculations to
characterize the free-energy landscape of the Si−O bond in the polymer backbone.