Using advanced field-based approaches to predict macroscale polymer nanocomposite phase behavior

Predictive phase diagrams significantly improve the refinement and optimization of materials for advanced applications. Unfortunately, theoretical phase diagrams of polymer nanocomposites (PNCs) are lacking, which is a result of limitations with conventional modeling approaches such as computational expense or critical approximations. Here we describe the development of field-based approaches in modeling PNCs and demonstrate their efficacy in modeling macroscale phase behavior. The exciting advances of these field-based approaches have led to the development of phase diagrams for an array of polymer nanocomposite systems. Examples of these systems include grafted nanoparticles in a polymer melt and the assembly of mixed brush nanoparticles in solution. We find the introduction of thermal fluctuations have a significant impact on the overall phase behavior of these systems. Specifically, thermal fluctuations are necessary to properly capture depletion interactions in grafted nanoparticle systems and to describe solution-based assembly where it is understood that thermal fluctuations are significant. Excitingly, we further show the versatility of these methods to other PNC systems and provide comparisons with analogous experiments.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.