Novel Colloidal Assembly Methods for the Preparation of Core-Shell Composite Materials

摘要

Colloidal assembly is a process by which particles ranging in size from nanometers to micrometers are organized into structures by mixing two or more particle types. Assembly is controlled by either specific or non-specific interactions between particles. Examples include chemical bonding, biological interactions, electrostatic interactions, capillary action and physical adsorption. The assembly process is performed such that smaller particles assemble around larger ones. In this paper, we report on colloidal assembly of polymer nanoparticles (50-200 nm diameter) onto silica particles (3-5 μm diameter) using specific chemical interactions (i.e. amine-aldehyde). Annealing the assembled composites at temperatures above the glass transition (T_g) of the polymer nanospheres allows polymer to flow and uniformly coat the microsphcrc surfaces. Polystyrene and poly(methyl methacrylate) nanospheres were used to produce such materials. Shell composites were created by mixing both nanosphere types prior to assembly/annealing. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the materials presented herein.