Self-assembly of tin oxide nanoparticles: localized percolating network formation in polymer matrix.

A novel method to prepare transparent antistatic films by trapping nanoparticles in thin surface layers is proposed, and high performance of the product is demonstrated. Coating solutions consisting of surface-active antimony-doped tin oxide (ATO) nanoparticles, an organic solvent mixture of high affinity with poly(methyl methacrylate) substrate, and an ultraviolet curable resin are used for the film formation. Antistatic property of the layer is obtained at ATO concentrations above the critical concentration for percolation. A scaling analysis of the data shows that the critical concentration (0.004 volume fraction) is extremely low as compared to the value predicted by the percolation theory for randomly packed systems as well as the values in ever developed composite films filled with ATO particles. Microscopic observation of the deposited layers indicates that percolating clusters of ATO particles are localized on the layer surfaces. The excellent electrical and optical properties of the layer are attributed to the characteristic microstructure.