Published online by Cambridge University Press: 11 February 2011
It has been theoretically predicted that a polymer chain in poor solvent conditions undergoes a phase transition from a collapsed globule to a stretched coil. In this paper, we present force-distance curves, obtained by atomic force microscopy (AFM), showing the characteristic forceplateau associated with this transition. We show that the magnitude of the force depends on the environment (interfacial energy) that the stretched coil experiences when it is pulled-out as it is predicted by the theory.