Skip to main content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Quantifying Strain via Buckling Instabilities in Surface Modified Polymer Brushes



Cassandra M. Reese, Wei Guo, Brittany J. Thompson, Phillip K. Logan, Christopher M. Stafford, Derek L. Patton


We present a quantitative method of measuring the compressive strain of wrinkled polymer films and coatings with knowledge of the “skin” thickness, wrinkle wavelength, and wrinkle amplitude. The derived analytical expression is validated with a well-studied model system, e.g., stiff, thin film (PS) bonded to a thick, compliant substrate (PDMS), comparing the applied strain and calculated strain for a series of PS film thicknesses. After validation, we use the analytical expression to quantify the applied swelling strain of previously reported wrinkled poly(styrene-alt-maleic anhydride) brush surfaces after surface modification, where the swelling strain was determined to increase with anhydride conversion in the “skin” layer of the modified brush. Finally, the applied strain is used to rationalize the observed persistence length of aligned wrinkles created during AFM lithography and subsequent solvent exposure. The ability to accurately determine the applied strain in wrinkled systems adds another tool to the metrology of instabilities in polymer thin films and coatings.


wrinkling, polymers, thin films, polymer brushes, strain
Created May 21, 2020, Updated June 12, 2020