Polymer Engineering Faculty Research

Polymer viscoelasticity and residual stress effects on nanoimprint lithography

Alamgir Karim


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