Study on diffusion process of nanoparticles in a PDMS layer using SPT technique

The Brownian motions of ZnS-AgInS2 (ZAIS) nanoparticles in a poly(dimethylsiloxane) (PDMS) layer were observed using the single-particle tracking (SPT) technique. The positions of each nanoparticle can be detected with spatial resolution of O(10 nm), and reflect the environment near each nanoparticles; thus, SPT can obtain information on the nanoscale structure or the spatial heterogeneity of the medium. In this study, ZAIS nanoparticles were illuminated by an excitation laser, and the emission of the nanoparticle was taken by using an EM-CCD camera. We analyzed each motion of the nanoparticle in the PDMS layer under two conditions: before and after adding a curing agent. The histograms of the diffusion coefficients had single peak for all of the particles in the layer before adding the curing agent and some particles in the layer after adding the one. On the other hand, the histogram of the other particles had two peaks. This indicates these particles diffused in the heterogeneous layer, showing spatial heterogeneous curing process in the layer.