December 5, 2014 - 3:00pm - 4:00pm
Three-dimensional (3D) self-assembly of mixed poly(tert-butyl acrylate) (PtBA)/ polystyrene (PS) brushes grafted on 67 nm silica nanoparticles is investigated by transmission electron tomography with or without being embedded in selective polymer matrices. The number-average molecular weights for PtBA and PS brushes are 22.2 and 23.4 kDa and their grafting densities are 0.51 and 0.34 chains/nm2, respectively. When cast from a neutral solvent, chloroform, to a flat surface, the self-assembly morphology is intimately affected by the solvent drying process. When blended in selective polymer matrices, the self-assembly morphology is influenced by the molecular weight of the matrix polymer. When the molecular weight of the matrix polymer is lower than that of the brush, the web-brush scenario is observed. When the molecular weight of the matrix polymer is higher than that of the brush, the dry-brush scenario is seen. This is the first time that detailed 3D self-assembled morphology is clearly observed for mixed homopolymer brushes grafted on nanoparticles.