Miscibility and Nanoparticle Diffusion in Ionic Nanocomposites.

Argyrios Karatrantos,Yao Koutsawa,Martin Kröger,Nigel Clarke,Philippe Dubois

doi:10.3390/polym10091010

Abstract

We investigate the effect of various spherical nanoparticles in a polymer matrix on dispersion, chain dimensions and entanglements for ionic nanocomposites at dilute and high nanoparticle loading by means of molecular dynamics simulations. The nanoparticle dispersion can be achieved in oligomer matrices due to the presence of electrostatic interactions. We show that the overall configuration of ionic oligomer chains, as characterized by their radii of gyration, can be perturbed at dilute nanoparticle loading by the presence of charged nanoparticles. In addition, the nanoparticle’s diffusivity is reduced due to the electrostatic interactions, in comparison to conventional nanocomposites where the electrostatic interaction is absent. The charged nanoparticles are found to move by a hopping mechanism.

Highlights

For a longer polymer matrix (N = 200), nanoparticle dispersion is not achieved for our polymers who carry charges at their terminals only
We have observed that the average radius of gyration of short polymers (N = 10 and N = 20) increases, in comparison to its bulk value, in ionic nanocomposites but only at low nanoparticle loading (10%) and as long as R g < R (Figure 4)
We investigated the structure and conformations of polymers and nanoparticle diffusion, for the first time in ionic nanocomposites containing small spherical nanoparticles up to high volume fraction, using a coarse grained model for nanoparticles and polymers by means of molecular dynamics simulations

Summary

Introduction

In the past three decades, polymer nanocomposites [1,2,3,4], where spherical, cylindrical or plate-like nanoparticles are finely distributed and dispersed [5,6,7] in a polymer matrix, have become of growing importance to industry and academia due to their advanced mechanical [8,9,10], thermal [11,12,13], tribological [14], rheological [15], and electrical properties [16] comparable to polymer blends.Because nanoparticles are increasingly being added to polymers, there is a motivation to explore how nanoparticles impact polymer dynamics [17,18,19,20], structure [21,22,23,24], morphology [25,26,27,28,29], stability [30], and how these features are correlated and how they impact macroscopic properties [1].Nanoparticle dispersion [31,32,33,34,35,36] (high degree of distribution/dispersion is needed for effective reinforcement [28,33] in the matrix) allows property “tuning” [24] and provides appropriate functionalities. In the past three decades, polymer nanocomposites [1,2,3,4], where spherical, cylindrical or plate-like nanoparticles are finely distributed and dispersed [5,6,7] in a polymer matrix, have become of growing importance to industry and academia due to their advanced mechanical [8,9,10], thermal [11,12,13], tribological [14], rheological [15], and electrical properties [16] comparable to polymer blends. There are three main ideas on how to achieve better nanoparticle dispersion. The second is to achieve a chemical favorable interaction between nanoparticle and polymer matrix [41,42,43,44]. The third idea is to let the interaction between nanoparticles and chains to be of ionic nature [5,6]. Nanoparticle aggregation has been observed for conventional polymer nanocomposites with weak interactions, such as polystyrene–silica

Methods

Results

Conclusion