Escape transition of a compressed polymer mushroom under good solvent conditions

A. Milchev; V. Yamakov; K. Binder

doi:doi:10.1209/epl/i1999-00442-2

DOI: 10.1209/epl/i1999-00442-2

Europhys. Lett, 47 (6), pp. 675-680 (1999)

Escape transition of a compressed polymer mushroom under good solvent conditions

A. Milchev ^1,2, V. Yamakov ^2,3 and K. Binder ¹

¹ Institut für Physik, Johannes-Gutenberg-Universität
Staudinger Weg 7, D-55099 Mainz, Germany
² Institute for Physical Chemistry, Bulgarian Academy of Sciences - 1113, Sofia, Bulgaria
³ Max-Planck-Institut für Polymerforshung
Ackermannweg 10, D-55128, Mainz, Germany

(received 5 February 1999; accepted in final form 12 July 1999)

PACS. 36.20 ${\rm -r}$ - Macromolecules and polymer molecules.
PACS. 36.20Ey - Conformation (statistics and dynamics).
PACS. 82.45 ${\rm +z}$ - Electrochemistry and electrophoresis.

Abstract:

The escape transition of a flexible polymer chain of chain length N, endgrafted at a hard wall and compressed by a piston of radius R, is studied by Monte Carlo simulation and by phenomenological arguments. In contrast to previous theories which have considered the transition as a function of a (fixed) height H of the piston above the wall, we consider the transition as a function of the conjugate variable, the force f acting on the piston. We find that the transition (which is sharp only for $N\rightarrow \infty$ ) is characterized by a flat region of f in the f vs. H isotherm, i.e. a jump in the height occurs at the transition from $H_{{\rm esc},t}$ to $H_{{\rm imp},t}$ , with $(H_{{\rm imp},t}-H_{{\rm esc},t})/H_{{\rm esc},t}\approx 0.26$ .

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