Previous
work has shown that a surface wave on amorphous <i>o</i>-terphenyl (OTP) decays by viscous flow at high temperatures
and by surface diffusion at low temperatures. We report that the surface
mass transport can be efficiently suppressed by low-concentration
polymers. Surface-grating decay has been measured for OTP containing
1 wt % polystyrene (PS, <i>M</i><sub>w</sub> = 1–8
kg/mol), which is miscible with OTP. The additive has no significant
effect on the decay kinetics in the viscous-flow regime, but a significant
effect in the surface-diffusion regime. In the latter case, surface
evolution slows down and becomes nonexponential (decelerating over
time). The effect increases with falling temperature and the molecular
weight of PS. These results are attributed to the very different mobility
of PS (slow) and OTP (fast) and their segregation during surface evolution,
and relevant for understanding the surface mobility of multicomponent
amorphous materials
