Polymer Viscoelasticity and Residual Stress Effects on Nanoimprint Lithography

The decay kinetics of polystyrene (PS) gratings are monitored by tracking the intensity of the first‐order laser diffraction peak as a function of annealing time. For low‐molecular‐mass PS (24 kg mol–1, blue circles), an exponential response suggests that the pattern decay is a surface‐tension‐ driven viscous flow. In high‐molecular‐mass PS (1007 kg mol–1, green circles) a complicated response includes a rapid elastic recovery, a power‐law creep, and a viscouslike flow (see figure).