Residual entropy in a model for the unfolding of single-polymer chainsE. Van der Straeten and J. Naudts
Departement Fysica, Universiteit Antwerpen - Groenenborgerlaan 171, 2020 Antwerpen, Belgium
received 10 September 2007; accepted in final form 20 November 2007; published January 2008
published online 14 December 2007
We study the unfolding of a single-polymer chain due to an external force. We use a simplified model which allows to perform all calculations in closed form without assuming a Boltzmann-Gibbs form for the equilibrium distribution. Temperature is then defined by calculating the Legendre transform of the entropy under certain constraints. The application of the model is limited to flexible polymers. It exhibits a gradual transition from compact globule to rod. The boundary line between these two phases shows reentrant behavior. This behavior is explained by the presence of residual entropy.
82.35.Lr - Physical properties of polymers.
05.20.-y - Classical statistical mechanics.
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