Localization and stretching of polymer chains at the junction of two surfaces

Abstract

We present a molecular dynamics study on the stretching of a linear polymer chain that is adsorbed at the junction of two intersecting flat surfaces of varying alignments. We observe a transition from a two-dimensional to one-dimensional (1D) structure of the adsorbed polymer when the alignment, i.e., the angle between the two surfaces that form a groove, θ, is below 135°. We show that the radius of gyration of the polymer chain Rg scales as Rg ∼ N(3/4) with the degree of polymerization N for θ = 180° (planer substrate), and the scaling changes to Rg ∼ N(1.0) for θ < 135° in good solvents. At the crossover point, θ = 135°, the exponent becomes 1.15. The 1D stretching of the polymer chain is found to be 84% of its contour length for θ ⩽ 90°. The center of mass diffusion coefficient D decreases sharply with θ. However, the diffusion coefficient scales with N as D ∼ N(-1), and is independent of θ. The relaxation time τ, for the diffusive motion, scales as τ ∼ N(2.5) for θ = 180° (planar substrate), which changes to τ ∼ N(3.0) for θ ⩽ 90°. At the crossover point, the exponent is 3.4, which is slightly higher than the 1D value of 3.0. Further, a signature of reptation-like dynamics of the polymer chain is observed at the junction for θ ⩽ 90° due to its strong 1D localization and stretching.

Scaling Behavior of Polymers at Liquid/Liquid Interfaces

“…11,12 If the experimental characterization of macromolecule dynamics at soft interfaces is difficult, their simulation is also challenging. The available literature [11][12][13][14][15][16][17][18] focuses only on the modelling of polymer confined between solid surfaces (flat as in a slit pore or rounded as in cylindrical pores) dissolved in a good solvent often modelled as a continuum defined by a friction coefficient and therefore ignoring any HI. For example Mukherji et al 19 performed molecular dynamics (MD) simulations of a beadand-spring polymer model adsorbed on an attractive corrugated solid surface using implicit (good) solvent.…”

Molecular shear heating and vortex dynamics in thermostatted two dimensional Yukawa liquids

“…This method of calculating temperature only depends upon the configurational information of the system, hence named configurational temperature. Influenced by the concept of configurational temperature a new method of thermostatting namely configurational thermostat, has been introduced by Delhommelle and Evans [25,26], Patra and Bhattacharya [27] and, Braga and Travis [23,24]. Due to its relative simplicity in implementation, we have chosen the Braga-Travis version of PUT.…”