Interfacial Compatibilization in Ternary Polymer Nanocomposites: Comparing Theory and Experiments

In this work, we examine binary and ternary nanocomposites of poly­(methyl methacrylate) grafted silica nanoparticles (PMMA-NP), in poly­(styrene-ran-acrylonitrile) (SAN), and poly­(methyl methacrylate) matrices as a platform to directly probe governing parameters guiding phase behavior and nanoparticle assembly in composite materials. Through the addition of PMMA matrix chains similar in molecular weight to the grafted PMMA chains and significantly smaller than the SAN matrix chains, we observe increased nanoparticle miscibility in off-critical compositions due to interfacial segregation of PMMA matrix chains. A simple interfacial model provides a general guideline for predicting the extent of compatibilization. Further insights on compatibilization behavior are provided by polymer particle pair correlation functions and structure factors obtained using polymer reference interaction site model theory calculations as well as polymer concentration profiles from molecular dynamics simulations. This study serves as a guideline to facilitate PNC processing and design of materials for a broad range of technological applications.