Stretching polymers in poor and bad solvents: Pullout peaks and an unraveling transition
Research School of Physical Sciences, Institute of Advanced Studies
Australian National University, ACT 0200, Australia
Accepted: 8 August 2003
Using analytic theory, numerical calculation and Langevin dynamics simulation we demonstrate the existence of a first-order unraveling transition in the stretching of a polymer chain in a poor solvent. The chain suddenly unravels from a “tadpole” or “ball and chain” configuration, to one where the ball shrinks to zero size. In the force curve this appears as a discontinuous drop in the force. This transition occurs under the conditions of most relevance for atomic-force microscope experiments, where the extension is the independent variable. Our simulations show marked hysteresis as well as many local peaks associated with the pullout of small portions of the chain.
PACS: 82.35.Lr – Physical properties of polymers / 87.15.Aa – Theory and modeling; computer simulation / 87.15.-v – Biomolecules: structure and physical properties
© EDP Sciences, 2003