Making Organic-Inorganic Nanocomposites via Selective Dispersion of PS-Tethered SiO2 Particles in Polystyrene-Block-Polymethylmethacrylate Copolymer

SiO2 nanoparticles have been dispersed selectively in the polystyrene (PS) microdomain of polystyrene-block-polymethylmethacrylate (PS-b-PMMA) block copolymer via the blending of PS-b-PMMA with PS-tethered SiO2. As observed by atomic force microscopy and scanning electron microscopy, the incorporation of SiO2 particles not only enlarges the PS microdomain but also reduces the surface energy of the PS microdomain and transforms the morphology from either lamellar layers or cylinders to islanded bicontinuous microstructures. Blending SiO2 particles with an excessive amount or with a particle size larger than that of the PS microdomain would pose an extreme constraint on the molecular rearrangement, unstabliize the microdomain separation, and even make the microdomain separation unobservable. The nanosize and the uniform distribution of the PS microdomain in the PS-b-PMMA polymer have thus enabled us to achieve a uniform distribution of the inorganic SiO2 particles in the organic polymeric matrix.