IR Spectroscopic Ellipsometry to Characterize Microfiltration Membranes

The porosity and thickness of microfiltration membranes are critical characteristics to understand the performance and properties. Here, we demonstrate the nondestructive characterization of two commercial microfiltration membranes using IR ellipsometry. The porous nature of these membranes effectively scatters visible light, but the longer IR wavelengths decrease depolarization and enable ellipsometric characterization of freestanding membranes with useful ellipsometric data primarily in the fingerprint region. Fits of the ellipsometric data provided the membrane thickness and both local and average porosity from the dielectric constant. The thicknesses of the membranes from ellipsometry agreed well with the measured thickness from SEM cross sections, while the average porosity estimated from the density of the membrane was slightly higher than the ellipsometry analysis, which can be accounted for by considering the incomplete densification of the membrane used to determine the refractive index of the polymer matrix. Moreover, the fit of the ellipsometric data indicated that the membranes are not uniform but rather have a measurable gradient in porosity that is difficult to detect from SEM alone. This work demonstrates the characterization of freestanding microfiltration membranes with IR ellipsometry, overcoming the limitation of visible light ellipsometry, and points toward potential for nondestructive determination of chemical and porosity gradients through the thickness of microfiltration membranes.

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Appl. Polym. Mater., copyright © 2023 American Chemical Society after peer review and technical editing by the publisher.

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Work Title IR Spectroscopic Ellipsometry to Characterize Microfiltration Membranes
Access
Open Access
Creators
  1. Huseyin Kaya
  2. Shouhong Fan
  3. Seong H. Kim
  4. Yifu Ding
  5. Bryan D. Vogt
Keyword
  1. Membranes
  2. Porosity
  3. Optical characterization
  4. PVDF
  5. Gradients
License In Copyright (Rights Reserved)
Work Type Article
Publisher
  1. ACS Applied Polymer Materials
Publication Date May 22, 2023
Publisher Identifier (DOI)
  1. https://doi.org/10.1021/acsapm.3c00083
Deposited May 06, 2024

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Version 1
published

  • Created
  • Added IRSE_MAST_final-1.pdf
  • Added Creator Huseyin Kaya
  • Added Creator Shouhong Fan
  • Added Creator Seong H. Kim
  • Added Creator Yifu Ding
  • Added Creator Bryan D. Vogt
  • Published
  • Updated
  • Updated Keyword Show Changes
    Keyword
    • Membranes, Porosity, Optical characterization, PVDF, Gradients