NMR spin diffusion measurements in disordered polymers: Insights and limitations

Eric G. Sorte, Amalie L. Frischknecht, and Todd M. Alam
Phys. Rev. Materials 3, 045602 – Published 19 April 2019
PDFHTMLExport Citation

Abstract

Nuclear magnetic resonance (NMR) spin diffusion measurements have been widely used to estimate domain sizes in a variety of polymer materials. In cases where the domains are well-described as regular, repeating structures (e.g., lamellar, cylindrical channels, monodispersed spherical domains), the domain sizes estimated from NMR spin diffusion experiments agree with the characteristic length scales obtained from small-angle x-ray scattering and microscopy. In our laboratory, recent NMR spin diffusion experiments for hydrated sulfonated Diels Alder poly(phenylene) (SDAPP) polymer membranes have revealed that assuming a simple structural model can often misrepresent or overestimate the domain size in situations where more complex and disordered morphologies exist. Molecular dynamics simulations of the SDAPP membranes predict a complex heterogeneous hydrophilic domain structure that varies with the degree of sulfonation and hydration and is not readily represented by a simple repeating domain structure. This heterogeneous morphology results in NMR-measured domain sizes that disagree with length scales estimated from the ionomer peak in scattering experiments. Here we present numerical NMR spin diffusion simulations that show how structural disorder in the form of domain size distributions or domain clustering can significantly impact the spin diffusion analysis and estimated domain sizes. Simulations of NMR spin diffusion with differing domain size distributions and domain clustering are used to identify the impact of the heterogeneous domain structure and highlight the limitations of using NMR spin diffusion techniques for irregular structures.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Received 22 January 2019

DOI:https://doi.org/10.1103/PhysRevMaterials.3.045602

©2019 American Physical Society

Physics Subject Headings (PhySH)

Polymers & Soft Matter

Authors & Affiliations

Eric G. Sorte1, Amalie L. Frischknecht2, and Todd M. Alam1,*

  • 1Department of Organic Materials Science, Sandia National Laboratories, Albuquerque, New Mexico 87185 USA
  • 2Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA

  • *Author to whom correspondence should be addressed: tmalam@sandia.gov

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 3, Iss. 4 — April 2019

Reuse & Permissions
Access Options
CHORUS

Article Available via CHORUS

Download Accepted Manuscript
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review Materials

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×