Deconvolution of Stress Interaction Effects from Atomic Force Spectroscopy Data across Polymer-Particle Interfaces

David W. Collinson, Matthew D. Eaton, Kenneth R. Shull, L. Catherine Brinson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Atomic force microscopy (AFM) is a powerful technique for imaging polymer nanocomposites as well as other systems with heterogeneous material properties on the nanoscale. However, the quantitative measurement of modulus is highly susceptible to convoluting structural effects due to the finite tip radius and stress field interactions with particles and substrates which are often termed the "substrate effect" or "thin film effect". We present an empirical master curve that can model the change in measured modulus (EMC) due to structural effects in an AFM indentation on a soft material near a stiff filler, using N121 and N660 carbon black-styrene-butadiene rubber nanocomposites as examples. Finite element analysis is combined with experimental AFM data across an interface at increasing indentation depths to create a robust method for confirming or rejecting the presence of an interphase layer in AFM. From the raw data, which is initially inconclusive, we reasonably estimate the width of the loosely bound layer (ζint) surrounding each (strongly interacting) N121 particle to be 50-60 nm after deconvolving the substrate effect. In comparison, we found no significant loosely bound layer around the (weakly interacting) N660 particles. While we have demonstrated this technique for polymer nanocomposites, we believe the strategy is broadly applicable to multiphase soft materials.

Original languageEnglish (US)
Pages (from-to)8940-8955
Number of pages16
JournalMacromolecules
Volume52
Issue number22
DOIs
StatePublished - Nov 26 2019

Funding

This work was supported by The Goodyear Tire & Rubber Company (PO#4510883960), NIST (70NANB14H012), NSF (BCS-1734981), and AFOSR (FA9550-18-1-0381) and made use of the EPIC and SPID facilities of Northwestern University’s NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. D.W.C. acknowledges financial support from Ryan Fellowship through the IIN at Northwestern University and a Fulbright Program grant sponsored by the Bureau of Educational and Cultural Affairs of the United States Department of State. M.D.E. acknowledges the support of the Department of Defense (DoD) through the National Defense Science and Engineering Graduate (NDSEG) program. The authors would like to thank the reviewers for their helpful and insightful comments.

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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