  Surface stress and surface energy are two fundamental parameters that
determine the surface properties of any materials. While it is commonly
believed that the surface stress and surface energy of liquids are identical,
the relationship between the two parameters in soft polymeric gels remains
debatable. In this work, we measured the surface stress and surface energy of
soft silicone gels with varying weight ratios of crosslinkers in soft wetting
experiments. Above a critical density, $k_0$, the surface stress was found to
increase significantly with crosslinking density while the surface energy
remained unchanged. In this regime, we can estimate a non-zero surface elastic
modulus that also increases with the ratio of crosslinkers. By comparing the
surface mechanics of the soft gels with their bulk rheology, the surface
properties near the critical density $k_0$ were found to be closely related to
the underlying percolation transition of the polymer networks.
