DIFFUSIVE 2-DIMENSIONAL SPREADING OF A POLYMER

We have measured the thickness profiles of ultrasmall (picoliter volume) droplets of polydimethylsiloxane during their spreading on a silver surface at central thicknesses below one monolayer. The resulting profile shapes can be approximated well by spherical caps, and the diffusion dynamics are quite different from those expected for pointlike particles. The experimental data are in remarkable agreement with Monte Carlo simulations of a spreading two-dimensional polymer lattice-gas, which are performed using the bond fluctuation method.