In this study we exemplify raster-scan abrasion with an AFM probe at high force (in "contact mode") to shear-displace relative soft (organic, polymeric) films on hard substrates, and nonperturbatively analyze the results at lower force. We delve into extra detail on Polyacrylamide films chemisorbed on silanized glass surfaces via ultraviolet-initiated attachment and crosslinking. This ultrathin film system is a technological platform for DNA microassays; more generally, thicker Polyacrylamide films are added as lubricious coatings on medical devices, [surmodics] One problem of interest to those engineering such films is measuring the degree of film swelling under aqueous immersion (and its relation to processing parameters). We present a methodology for this measurement using force-distance curve mapping over the scan-abraded and surrounding region. We demonstrate that conventional topographic imaging (i.e., under setpoint feedback) of this region is an erroneous means of quantifying swollen film thickness because of substantial mechanical compliance atop the swollen polymer; whereas force-distance mapping accounts for this compliance, and furthermore reveals interesting macromolecular behavior. We exemplify some algorithms for more advanced and quantitative analyses of these datasets.
|Original language||English (US)|
|Title of host publication||TechConnect Briefs 2018 - Advanced Materials|
|Editors||Matthew Laudon, Fiona Case, Fiona Case, Bart Romanowicz|
|Number of pages||4|
|State||Published - Jan 1 2018|
|Event||11th Annual TechConnect World Innovation Conference and Expo, Held Jointly with the 20th Annual Nanotech Conference and Expo,the 2018 SBIR/STTR Spring Innovation Conference, and the Defense TechConnect DTC Spring Conference - Anaheim, United States|
Duration: May 13 2018 → May 16 2018
|Name||TechConnect Briefs 2018 - Advanced Materials|
|Conference||11th Annual TechConnect World Innovation Conference and Expo, Held Jointly with the 20th Annual Nanotech Conference and Expo,the 2018 SBIR/STTR Spring Innovation Conference, and the Defense TechConnect DTC Spring Conference|
|Period||5/13/18 → 5/16/18|
Bibliographical noteFunding Information:
Support was provided by the Industrial Partnership for Research in Interfacial and Materials Engineering at the University of Minnesota and by Surmodics, Inc. Parts of this work were carried out in the University of Minnesota's materials Characterization Facility, which has received partial support from NSF through the MRSEC program.
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- Atomic force microscopy
- Biocompatible polymer
- Ultrathin films