title: Mechanically activated rupture of single covalent bonds: evidence of force induced bond hydrolysis.
abstract: We have used temperature-dependent single molecule force spectroscopy to stretch covalently anchored carboxymethylated amylose (CMA) polymers attached to an amino-functionalized AFM cantilever. Using an Arrhenius kinetics model based on a Morse potential as a one-dimensional representation of covalent bonds, we have extracted kinetic and structural parameters of the bond rupture process. With 35.5 kJ mol(-1), we found a significantly smaller dissociation energy and with 9.0 × 10(2) s(-1) to 3.6 × 10(3) s(-1) also smaller Arrhenius pre-factors than expected for homolytic bond scission. One possible explanation for the severely reduced dissociation energy and Arrhenius pre-factors is the mechanically activated hydrolysis of covalent bonds. Both the carboxylic acid amide and the siloxane bond in the amino-silane surface linker are in principle prone to bond hydrolysis. Scattering, slope and curvature of the scattered data plots indicate that in fact two competing rupture mechanisms are observed.
authors.affiliation: Munich University of Applied Sciences, Department of Precision- and Micro-Engineering, Engineering Physics, Munich, Germany.
authors.forename: Sebastian W
authors.initials: SW
authors.lastname: Schmidt
authors.forename: Alfred
authors.initials: A
authors.lastname: Kersch
authors.forename: Martin K
authors.initials: MK
authors.lastname: Beyer
authors.forename: Hauke
authors.initials: H
authors.lastname: Clausen-Schaumann