Force-extension curves for broken-rod macromolecules: Dramatic effects of different probing methods for two and three rods

J Chem Phys. 2015 Apr 28;142(16):164905. doi: 10.1063/1.4919295.

Abstract

We study force-extension curves of a single semiflexible chain consisting of several rigid rods connected by flexible spacers. The atomic force microscopy and laser optical or magnetic tweezers apparatus stretching these rod-coil macromolecules are discussed. In addition, the stretching by external isotropic force is analyzed. The main attention is focused on computer simulation and analytical results. We demonstrate that the force-extension curves for rod-coil chains composed of two or three rods of equal length differ not only quantitatively but also qualitatively in different probe methods. These curves have an anomalous shape for a chain of two rods. End-to-end distributions of rod-coil chains are calculated by Monte Carlo method and compared with analytical equations. The influence of the spacer's length on the force-extension curves in different probe methods is analyzed. The results can be useful for interpreting experiments on the stretching of rod-coil block-copolymers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Macromolecular Substances / chemistry*
  • Magnetic Phenomena
  • Mechanical Phenomena*
  • Models, Molecular*
  • Molecular Conformation
  • Monte Carlo Method
  • Probability

Substances

  • Macromolecular Substances