Dispersion and orientation patterns in nanorod-infused polymer melts

Abstract

Introducing nanorods into a polymeric matrix can enhance the physical and mechanical properties of the resulting material. In this paper, we focus on understanding the dispersion and orientation patterns of nanorods in an unentangled polymer melt, particularly as a function of nanorod concentration, using Molecular Dynamics (MD) simulations. The system is comprised of flexible polymer chains and multi-thread nanorods that are equilibrated in the NPT ensemble. All interactions are purely repulsive except for those between polymers and rods. Results with attractive versus repulsive polymer-rod interactions are compared and contrasted. The concentration of rods has a direct impact on the phase behaviour of the system. At lower concentrations rods phase separate into nematic clusters, while at higher concentrations more isotropic and less structured rod configurations are observed. A detailed examination of the conformation of the polymer chains near the rod surface shows extension of the chains along the director of the rods (especially within clusters). The dispersion and orientation of the nanorods is a result of the competition between depletion entropic forces responsible for the formation of rod clusters, the enthalpic effects that improve mixing of rods and polymer, and entropic losses of polymers interpenetrating rod clusters.

Revealing the reinforcing effect of a nanorod network on a polymer matrix through molecular dynamics simulations

“…The dispersion state of NRs is determined by the interfacial interactions, which include NR–NR interfacial interactions ( ε nn ) and NR–polymer interfacial interactions ( ε np ). 36 We commence with the discussion of the NR dispersion behavior at various ε nn , as displayed in Fig. 1(a).…”

Dynamic dielectric function and phonon self-energy from electrons strongly correlated with acoustic phonons in 2D Dirac crystals

“…where we have integrated over ξ y . The employment of numerical methods in different branches of physics and science has become more common in recent years [57][58][59][60][61]. Using a MAT-LAB routine, we solve equation (11) numerically by sums.…”

Complex Smectic Phases in Polymer-Grafted Shape-Uniform Cellulose Nano-Crystals

“…However, to our knowledge, no systematic studies into the LC behavior of polymer grafted CNCs have been performed to date. While simulations of nanorod–polymer mixtures are now relatively widespread, − very few simulations of polymer grafted nanorods exist, and it is only very recently that computational attempts have been made to understand their self-assembly. These studies have been so far limited to single molecules, , disordered thin films in which polymer grafting is noted to disrupt the LC ordering and bulk studies into mechanical properties, dispersion effects, , graft locations and extremely low grafting densities where single polymer chains are attached to the rod tip which are computationally less demanding and allow for their LC behavior to be explored. , In none of these studies, however, is LC like behavior observed, likely due to low effective aspect ratios of short rods grafted with long polymers, patchy grafting, or improper crystallization protocols used to grow LC phases.…”