Skip to main page 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.

Https

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.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2008 Feb 21;4(3):564-569.
doi: 10.1039/b713263h.

Creasing instability of surface-attached hydrogels

Affiliations

Creasing instability of surface-attached hydrogels

Verónica Trujillo et al. Soft Matter. .

Abstract

The unidirectional expansion of a thin surface-attached polymer gel upon swelling by solvent generates a biaxial compressive stress within the gel. For sufficiently large stresses, a mechanical instability can occur in which the free surface locally buckles and folds against itself to form creases. This instability has important implications for the design of biomaterials, smart surfaces, and sensors, since it places a fundamental limit on the amount of swelling that a surface-attached polymer layer may undergo without forming topographical features. However, while this instability was first observed more than a century ago, the amount of compression necessary to form creases has never been systematically studied. Using a model system of poly(acrylamide-co-sodium acrylate) hydrogels, we establish that the onset of creasing corresponds to an effective linear compressive strain of ∼ 0.33, or a change in thickness by a factor of ∼ 2. Remarkably, this value varies only slightly with modulus over a range of ∼ 0.6-24 kPa and is independent of gel thickness from 3 μm-1 mm, in excellent agreement with theoretical predictions. This instability is reversible, with creases disappearing as the degree of swelling is lowered, but surfaces exhibit a significant memory for crease locations when subsequently re-swelled.

PubMed Disclaimer

Similar articles

Cited by

LinkOut - more resources

-