The control of Silica nanoparticles on the phase separation of poly(methyl methacrylate)/poly(styrene‐co‐acrylonitrile) blends

The influence of silica nanoparticles on the LCST phase behavior and phase separation kinetics of a blend consisting of poly(methyl methacrylate) (PMMA) and poly(styrene-co-acrylonitrile) (SAN), was studied via a high-throughput experimentation (HTE) approach, which combines a composition (f) and a temperature (T) gradient. The evolution of the phase separation process was studied by optical microscopy (OM), small-angle light scattering (SALS), transmission electron microscopy (TEM). Depending on the specific interaction between the silica surface and the polymers, the distribution of silica particles during phase separation can be controlled to be either in one of the polymer phases or at the PMMA/SAN interface. The hydrophilic silica nanoparticles preferentially migrated to the PMMA phase, leading to a slow down of the coarsening rate, which may be related to a reduction of the mobility of PMMA because of an increase of the silica concentration. The hydrophobic silica nanoparticles were localized at the PMMA/SAN interface, the inhibition of coalescence corresponds to the presence of a solid barrier (the nanoparticles) between the polymers which prevents the coarsening process.