Substrate-dependent dispersion behavior of polymer-protected Pt colloid studied by SPM

The dispersion behavior of PVP-protected platinum colloids on mica and gold is studied by scanning probe microscopy (STM and AFM). Both the distribution pattern and morphology of colloids are different on the two substrates. It is found that the dispersion results are determined not only by lateral capillary force but also by the evaporation rate of solvent. For dispersion on mica surfaces, the colloids form regular patterns at the edges of polymer patches that are stripped off the colloids. On gold surfaces, the protected colloids disperse randomly and preserve their core-shell structures. The reason is attributed to the different evaporation rate of solvent on two substrates, which in turn induces the difference in the effect of the lateral capillary force.