Cover Image, Volume 50, Issue 22


original image

The cover shows thermal wrinkles that develop on the surface of a metal capped polymer thin film, as presented by Edwin P. Chan, Qinghuang Lin, and Christopher M. Stafford on page 1556. These wrinkles form in composite thin films at elevated temperatures due to thermal expansion differences of the materials. The wrinkle wavelength evolves with annealing time and temperature, and can be directly related to the elastic and viscous properties of the polymer. In this work, thermal wrinkling is demonstrated as a thin film measurement tool for quantifying the elastic and viscous properties of polymer layers with varying degrees of crosslinking.