Breakdown of Dynamic Scaling in Thin Film Binary Liquids Undergoing Phase Separation
The kinetics of phase separation in thin polymer blend films displaying discrete and bicontinuous domain morphologies are examined. For discrete domains, the correlation length ξ grows as t1/3, in agreement with a coalescence model. By plotting ξ/d vs t/ti (initiation time), universal growth behavior is obtained for thickness values (d) from 1000 to 190 nm. In contrast, bicontinuous domains grow with a decreasing exponent, 0.62 to 0.28, as d decreases from 900 to 90 nm (i.e., no universal growth). This slowing down with reduced dimensionality suggests suppression of lateral hydrodynamic pumping.