Europhys. Lett.
Volume 69, Number 1, January 2005
Page(s) 102 - 108
Section Condensed matter: structure, mechanical and thermal properties
Published online 08 December 2004
Europhys. Lett., 69 (1), pp. 102-108 (2005)
DOI: 10.1209/epl/i2004-10304-5

Force-induced desorption of a linear polymer chain adsorbed on an attractive surface

P. K. Mishra, S. Kumar and Y. Singh

Department of Physics, Banaras Hindu University - Varanasi-221 005, India

received 7 April 2004; accepted in final form 27 October 2004
published online 8 December 2004

We consider a model of self-avoiding walk on a lattice with on-site repulsion and an attraction for every vertex of the walk visited on the surface to study force-induced desorption of a linear polymer chain adsorbed on an attractive surface and use the exact enumeration technique for analyzing how the critical force for desorption $f_{\ab{c}}(T)$ depends on the temperature. The curve $f_{\ab{c}}(T)$ gives the boundary separating the adsorbed phase from the desorbed phase. Our results show that in two dimensions, where surface is a line, the force $f_{\ab{c}}(T)$ increases monotonically as temperature is lowered and becomes almost constant at very low temperatures. In case of three dimensions we, however, find re-entrance, i.e. $f_{\ab{c}}(T)$ goes through a maximum as temperature is lowered. The behaviour of the polymer chain at different values of temperature and force is examined by calculating the probability distribution of the height from the surface of the vertex at which external force is applied.

68.18.Jk - Phase transitions.
68.47.Pe - Langmuir-Blodgett films on solids; polymers on surfaces; biological molecules on surfaces.
36.20.-r - Macromolecules and polymer molecules.

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