Dynamics of pulled desorption with effects of excluded volume interaction: The p-Laplacian diffusion equation and its exact solution

Abstract

We analyze the dynamics of desorption of a polymer molecule which is pulled at one of its ends with force $f$, trying to desorb it. We assume a monomer to desorb when the pulling force on it exceeds a critical value $f_c$. We formulate an equation for the average position of the $n^{th}$ monomer, which takes into account excluded volume interaction through the blob-picture of a polymer under external constraints. The approach leads to a diffusion equation with a $p$-Laplacian for the propagation of the stretching along the chain. This has to be solved subject to a moving boundary condition. Interestingly, within this approach, the problem can be solved exactly in the trumpet, stem-flower and stem regimes. In the trumpet regime, we get $\tau ={\tau }_0{n}_d^2$ where $n_d$ is the number of monomers that have desorbed at the time $\tau$. ${\tau }_0$ is known only numerically, but for $f$ close to $f_c$, it is found to be ${\tau }_0\sim f_c/(f^{2/3}-f_c^{2/3})$. If one used simple Rouse dynamics, this result changes to {\normalsize $\tau \sim f_c{n}_d^2/(f-f_c)$.} In the other regimes too, one can find exact solution, and interestingly, in all regimes $\tau \sim n_d^2$.

6 pages, 2 figures

References in corpus (4)

• Nonequilibrium dynamics of polymer translocation and straightening
• Force-induced desorption of a linear polymer chain adsorbed on an attractive surface
• Forced-induced desorption of a polymer chain adsorbed on an attractive surface - Theory and Computer Experiment
• Pulling an adsorbed polymer chain off a solid surface

Cited by in corpus (2)

• Dragging a polymer in a viscous fluid: steady-state and transient
• Polymer Detachment Kinetics from Adsorbing Surface: Theory, Simulation and Similarity to Infiltration into Porous Medium