Nature440, 191-194 (9 March 2006) | doi:10.1038/nature04576
Adsorption-induced scission of carbon–carbon bonds
Sergei S. Sheiko1, Frank C. Sun1, Adrian Randall1, David Shirvanyants1, Michael Rubinstein1, Hyung-il Lee2 and Krzysztof Matyjaszewski2
Covalent carbon–carbon bonds are hard to break. Their strength is evident in the hardness of diamonds1, 2 and tensile strength of polymeric fibres3, 4, 5, 6; on the single-molecule level, it manifests itself in the need for forces of several nanonewtons to extend and mechanically rupture one bond. Such forces have been generated using extensional flow7, 8, 9, ultrasonic irradiation10, receding meniscus11 and by directly stretching a single molecule with nanoprobes12, 13, 14, 15, 16. Here we show that simple adsorption of brush-like macromolecules with long side chains on a substrate can induce not only conformational deformations17, but also spontaneous rupture of covalent bonds in the macromolecular backbone. We attribute this behaviour to the fact that the attractive interaction between the side chains and the substrate is maximized by the spreading of the side chains, which in turn induces tension along the polymer backbone. Provided the side-chain densities and substrate interaction are sufficiently high, the tension generated will be strong enough to rupture covalent carbon–carbon bonds. We expect similar adsorption-induced backbone scission to occur for all macromolecules with highly branched architectures, such as brushes and dendrimers. This behaviour needs to be considered when designing surface-targeted macromolecules of this type—either to avoid undesired degradation, or to ensure rupture at predetermined macromolecular sites.
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
Center for Macromolecular Engineering, Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
Correspondence to: Sergei S. Sheiko1 Correspondence and requests for materials should be addressed to S.S.S. (Email: sergei@email.unc.edu).
