Abrasive scanning with AFM on biocompatible polymers: Measuring dry vs. swollen film thickness and probing properties

G. Haugstad, K. Wormuth

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

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 languageEnglish (US)
Title of host publicationTechConnect Briefs 2018 - Advanced Materials
EditorsMatthew Laudon, Fiona Case, Fiona Case, Bart Romanowicz
PublisherTechConnect
Pages16-19
Number of pages4
Volume1
ISBN (Electronic)9780998878225
StatePublished - Jan 1 2018
Event11th 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 2018May 16 2018

Publication series

NameTechConnect Briefs 2018 - Advanced Materials
Volume1

Conference

Conference11th 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
CountryUnited States
CityAnaheim
Period5/13/185/16/18

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Keywords

  • Atomic force microscopy
  • Biocompatible polymer
  • Lubricity
  • Nanotribology
  • Swelling
  • Ultrathin films

Cite this

Haugstad, G., & Wormuth, K. (2018). Abrasive scanning with AFM on biocompatible polymers: Measuring dry vs. swollen film thickness and probing properties. In M. Laudon, F. Case, F. Case, & B. Romanowicz (Eds.), TechConnect Briefs 2018 - Advanced Materials (Vol. 1, pp. 16-19). (TechConnect Briefs 2018 - Advanced Materials; Vol. 1). TechConnect.