Correlating Nanoparticle Dispersion to Surface Mechanical Properties of TiO2/Polymer Composites
The main objectives of this study are to characterize the nanoparticle dispersion in polymeric matrices with different mixing chemistry conditions; and to correlate dispersion to surface mechanical properties of the nanopaticle-polymer system. Two types of TiO2 nanoparticles (with and without surface treatment) were chosen to mix in two polymeric matrices of different chemistries: water-borne butyl-acrylic styrene latex coating (Latex) and solvent-borne acrylic urethane (AU). Nanoparticle dispersion (cluster size and spatial distribution) was characterized using laser scanning confocal microscopy (LSCM). Overall, Particle A (without surface treatment) dispersed better than Particle B (with organic dispersant) in both systems and the Particle A/AU system exhibited the best dispersion state. Surface mechanical properties, such as hardness and Young s modulus at micron and sub-micron length scales were determined from depth sensing indentation. The surface mechanical properties were strongly affected by the dispersion of nanoparticle clusters, and a good correlation was found between locations of the clusters near surface and the modulus-depth mapping.