The Effect of Dispersing Solvent Quality on the Microstructures and Properties of Polymer Nanocomposites

When nanoparticles are incorporated into the polymer matrix in polymer nanocomposites (PNCs), a good dispersion is required to achieve the desired physical properties. The size of particle/polymers, surface chemistry of particles, and grafting/adsorption polymer density on nanoparticles can affect the polymer-nanoparticle interactions at the interfaces and thus can change the state of dispersions. However, relatively less attention is paid to the role of the solvent for initial dispersion.
In this study, we show that the initial interaction of particle/polymer with dispersing solvent can be important, changing the final microstructure and rheological property of PNCs. The dispersing solvent only exists for initial dispersions of nanoparticles and completely evaporates during production; however, it can change the adsorption behavior of the polymers onto nanoparticles. The model systems consisted of silica nanoparticles in poly-(ethylene glycol) where dispersing solvents, polymer chain length and particle volume fraction are varied. The detailed characterization was performed with small angle X-ray scattering, NMR, and rheometry experiments.