Computational studies of polymer nanocomposites from mineral clays
Polymer nanocomposites have attracted considerable interest and investment in research and development worldwide in the past decade. Clay minerals are regarded as promising precursors for nanoparticles due to their unique layered structure, rich intercalation chemistry and low cost. This project aims to investigate, by means of molecular modeling techniques, the fundamentals of organoclays and polymer nanocomposites, in particular, their interfacial molecular structure and interactions. Such fundamental understanding will provide a guideline for the surface modification of clays, the dispersion of clay platelets in the target polymer matrix as well as the design, manufacturing and property controlling of polymer nanocomposites.
Major achievements
As an extension of our previous study on intercalated nanocomposites, molecular models of exfoliated nanocomposites have been developed which consist of one clay plates surrounded by a number of surfactants and nylon 6 chains.
Evaluation has been made to various force fields for their potential application to clay-polymer nanocomposite systems. The Consisten Valence Force Field (CVFF) with moderate improvement was found to be an ideal force field.
A series of molecular dynamics (MD) simulations have been performed to study the molecular structure and interactions at the interface of nylon 6-clay exfoliated nanocomposites. Quantification has been made to the effective thickness of the polymer-clay interface and effective nanoparticle size based on the simulated molecular structure and behaviours.
Future plans and directions
In the future, we will use MD simulation to calculate the mechanical properties of the effective clay platelet, which is a great step toward the prediction of the mechanical properties of clay-polymer exfoliated nanocomposites. Meanwhile, the effects of various factors (e.g., cationic exchangeable capacity of clay, surfactant) on the effective interface thickness and platelet properties will be studied.
Collaborations
Prof Donald R Paul, University of Texas at Austin (USA)
