Effect of bending flexibility on the phase behavior and dynamics of rods

Abstract

Articles you may be interested inThe phase behavior, structure, and dynamics of rodlike mesogens with various flexibility using dissipative particle dynamics simulation J. Chem. Phys. 133, 144911 (2010) Effect of bending flexibility on the phase behavior and dynamics of rods Saber Naderi 1,2,a) and Paul van der Schoot 1,3 We study by means of molecular and Brownian dynamics simulations the influence of bending flexibility on the phase behavior and dynamics of monodisperse hard filamentous particles with an aspect ratio of 8 and persistence lengths equal to 3 and 11 times the particle length. Although our particles are much shorter, the latter corresponds to the values for wild-type and mutant fd virus particles that have been subject of a recent experimental study, where the diffusion of these particles in the nematic and smectic-A phase was investigated by means of video fluorescence microscopy [E. Pouget, E. Grelet, and M. P. Lettinga, Phys. Rev. E 84, 041704 (2011)]. In agreement with theoretical predictions and simulations, we find that for the more flexible particles (shorter persistence length) the nematic (N) to smectic-A (Sm-A) phase transition shifts to larger values of the particle density. Interestingly, we find that for the more rigid particles (larger persistence length), the smectic layer-tolayer distance decreases monotonically with increasing density, whereas for the more flexible ones, it first increases, reaches a maximum and then decreases. For our more flexible particles, we find a smectic-B phase at sufficiently high densities. Moreover, in line with experimental observations and theoretical predictions, we find heterogeneous dynamics in the Sm-A phase, in which particles hop between the smectic layers. We compare the diffusion of our two types of particle at identical values of smectic order parameter, and find that flexibility does not change the diffusive behavior of particles along the director yet significantly slows down the diffusion perpendicular to it. In our simulations, the ratio of diffusion constants along and perpendicular to the director decreases just beyond the N-Sm-A phase transition for both our stiff and more flexible particles. © 2014 AIP Publishing LLC.

Modeling the Effect of Polymer Chain Stiffness on the Behavior of Polymer Nanocomposites

“…65,66 More generally, the I/N phase transition has been reported to be intimately related to the ratio l/p. 64,67 Consequently, the value of K θ at which we observe the I/N phase transition, would not be conserved after modifying the length or the density of chains in the system. We also notice that stiff rod-like chains might not form a nematic phase if their length-to-diameter ratio is not large enough, regardless of the value of K θ , and an isotropic-to-smectic phase transition would be rather observed.…”

The smectic phase in semiflexible polymer materials: A large scale molecular dynamics study

“…From these considerations it is clear that such simulations require the use of an efficient but also versatile simulation software allowing the study of systems containing of the order of million effective monomeric units. Previous efforts using a model with strongly overlapping beads, restricted attention to a single chain length (N = 9) using N = 600 chains in total [18], or N = 4464 chains with N = 17 beads [19], or N = 4608 chains with 13 ≤ N ≤ 21 [20]. The aim of the present work, however, is the study of much larger systems, e.g., with up to N N = 1694784 monomeric units to ensure that the results are not affected by systematic finite size effects.…”

Self-organisation of semi-flexible rod-like particles

“…Over the past few decades, interest in lyotropic liquid crystals has increased significantly, in part because of potential applications and in part because of the development of wellcontrolled model particles 8,9 . Indeed, lyotropic liquid crystals have been intensively investigated experimentally [10][11][12][13] , theoretically [14][15][16][17][18] and with the aid of computer simulations [19][20][21][22][23][24][25] .…”