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

• Published in: The Journal of chemical physics Vol. 142; no. 16; p. 164905
• Main Authors: Alexeev, A. V., Maltseva, D. V., Ivanov, V. A., Klushin, L. I., Skvortsov, A. M.
• Format: Journal Article
• Language: English
• Published: United States American Institute of Physics 28.04.2015
• Subjects: Atomic force microscopy; Block copolymers; Chains; Coils; COMPARATIVE EVALUATIONS; Computer simulation; COMPUTERIZED SIMULATION; COPOLYMERS; DIAGRAMS; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; LASER RADIATION; Macromolecular Substances - chemistry; Macromolecules; Magnetic Phenomena; Mechanical Phenomena; MICROSCOPY; Models, Molecular; Molecular Conformation; MOLECULES; MONTE CARLO METHOD; Monte Carlo simulation; Probability; PROBES; RODS; SPACERS; Stretching
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.4919295

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.