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arxiv: 1906.10394 · v1 · pith:TNIHOFFCnew · submitted 2019-06-25 · ⚛️ physics.app-ph · cond-mat.mtrl-sci

Graphene/Polyelectrolyte Layer-by-Layer Coatings for Electromagnetic Interference Shielding

Cristina Valles , Xiao Zhang , Jianyun Cao , Fei Lin , Robert J. Young , Antonio Lombardo , Andrea C. Ferrari , Laura Burk
show 2 more authors
Rolf Mulhaupt Ian A. Kinloch
This is my paper

Pith reviewed 2026-05-25 16:19 UTC · model grok-4.3

classification ⚛️ physics.app-ph cond-mat.mtrl-sci
keywords grapheneEMI shieldinglayer-by-layer coatingreduced graphene oxidepolyelectrolyteelectromagnetic interferencespray depositionthin films
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The pith

Layer-by-layer graphene-polyelectrolyte coatings achieve 29 dB electromagnetic shielding at 6 micrometers thickness.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper shows how alternating spray deposition of reduced graphene oxide and a positively charged polyelectrolyte builds thin, ordered conductive films. These films reach high shielding effectiveness despite low thickness and moderate filler loading. A ten-bilayer coating 6 micrometers thick with 19 percent graphene by volume delivers 29 dB of shielding. This value tops results from thicker graphene papers and composites that contain more filler material. The work highlights how flake size and deposition control influence the final electrical and shielding properties.

Core claim

By using a spray layer-by-layer method to assemble reduced electrochemically-exfoliated graphene oxide flakes with polyethyleneimine, the authors create 6 micrometer thick coatings that provide 29 dB EMI shielding at 19 vol.% loading, surpassing previously reported thicker materials with higher graphene contents.

What carries the argument

Alternating self-assembly of negatively charged reduced graphene oxide and positively charged polyelectrolyte through spray layer-by-layer deposition, which orders the flakes to form conductive pathways.

If this is right

  • Microscale thick coatings become viable for EMI shielding in compact devices where space and weight matter.
  • Lower volumes of graphene suffice when flakes are arranged in ordered layers rather than dispersed randomly.
  • Electrical properties can be tuned by selecting graphene flakes of specific diameters and adjusting the number of layers.
  • Scalable spray processing enables application on large or irregular surfaces for practical shielding.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The ordered structure from LbL assembly may reduce the percolation threshold for conductivity compared to bulk composites.
  • Similar techniques could be tested with other two-dimensional materials to create shielding layers with additional functions such as transparency or flexibility.
  • If the spray method proves robust, it could be adapted for roll-to-roll manufacturing of shielding films.

Load-bearing premise

EMI shielding effectiveness values reported in different studies can be compared directly without accounting for variations in measurement setup, frequency range, or sample geometry, and that the stated 19 vol.% loading accurately measures the true graphene content.

What would settle it

Performing EMI shielding tests on the new 6 micrometer coatings and on the thicker reference materials using the exact same instrument, sample mounting, and frequency sweep to check if the 29 dB value still exceeds the others.

Figures

Figures reproduced from arXiv: 1906.10394 by Andrea C. Ferrari, Antonio Lombardo, Cristina Valles, Fei Lin, Ian A. Kinloch, Jianyun Cao, Laura Burk, Robert J. Young, Rolf Mulhaupt, Xiao Zhang.

Figure 1
Figure 1. Figure 1: We show how the microstructure, level of orientation of the graphene flakes and electrical properties of the LbL coatings develop as a function of the amount of reduced graphene oxide deposited per cycle, while keeping the amount of PEI and n constant, and we relate it with their EMI shielding effectiveness. An outstanding maximum EMI SE of 29 dB was obtained for a 6 μm thick (PEI/RGO)10 coating with 19 vo… view at source ↗
Figure 1
Figure 1. Figure 1: Schematic of the spray coating approach used to fabricate the LbL coatings through alternating the absorption of negatively-charged TRGO and a positively-charged polyelectrolyte (PEI) on a PET substrate, rendering (PEI/TRGO)n coatings (n = number of bi-layers). To further characterize the layered microstructure of these coatings, polarized Raman spectroscopy was used. Polarized Raman spectroscopy has been … view at source ↗
read the original abstract

Electromagnetic interference (EMI) shielding coating materials with thicknesses in the microscale are required in many sectors, including communications, medical, aerospace and electronics, to isolate the electromagnetic radiation emitted from electronic equipment. We report a spray, layer-by-layer (LbL) coating approach to fabricate micron thick, highly-ordered and electrically-conductive coatings with exceptional EMI shielding effectiveness (EMI SE >4830 dB/mm), through the alternating self-assembly of negatively-charged reduced graphene oxide (RGO) and a positively-charged polyelectrolyte (PEI). The microstructure and resulting electrical properties of the (PEI/RGO)n LbL structures are studied as function of increasing mass of graphene deposited per cycle (keeping the PEI content constant), number of deposited layers (n), flake diameter and type of RGO. A strong effect of the lateral flake dimensions on the electrical properties is observed, which also influences the EMI SE. A maximum EMI SE of 29 dB is obtained for a 6 um thick (PEI/RGO)10 coating with 19 vol.% loading of reduced electrochemically-exfoliated graphene oxide flakes with diameters ~3um. This SE performance exceeds those previously reported for thicker graphene papers and bulk graphene/polymer composite films with higher RGO or graphene nanoplatelets contents, which represents an important step towards the fabrication of thin and light-weight high-performance EMI shielding structures.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The paper reports a spray-based layer-by-layer (LbL) fabrication method for micron-thick (PEI/RGO)n coatings using reduced graphene oxide flakes and polyelectrolyte. It examines effects of flake diameter, layer number, and RGO type on electrical properties and EMI shielding effectiveness (SE). The central experimental result is a maximum SE of 29 dB achieved with a 6 μm thick (PEI/RGO)10 coating containing 19 vol.% electrochemically exfoliated RGO flakes of ~3 μm diameter; this is claimed to surpass prior thicker graphene papers and bulk composites despite lower thickness and moderate filler loading.

Significance. If the reported SE values and volume-fraction determinations prove reproducible and directly comparable to literature, the work would demonstrate a practical route to thin, ordered conductive coatings with competitive EMI performance. The LbL spray approach offers microstructural control that could be useful for lightweight shielding in electronics and aerospace; the observed dependence of conductivity on flake lateral size is a useful materials insight.

major comments (3)
  1. [Abstract] Abstract: The headline claim that 29 dB at 6 μm and 19 vol.% exceeds prior reports for thicker films with higher loadings is load-bearing for the paper’s contribution, yet the abstract (and presumably the results section) provides neither error bars on the SE value, repeated-measurement statistics, nor the exact frequency band and test geometry (waveguide vs. free-space) used. Without these, direct numerical comparison to literature values cannot be verified.
  2. [Abstract] Abstract / Experimental section: The 19 vol.% RGO loading is stated without describing the determination method (mass balance after deposition, TGA, density measurement, or cross-sectional image analysis). Because the superiority claim rests on achieving high SE at comparatively low loading, an unvalidated vol.% figure undermines the central performance comparison.
  3. [Abstract] Abstract: No baseline data (uncoated substrate SE, pure PEI SE, or single-layer controls) or statistical analysis of the SE versus thickness/loading trends are mentioned. These omissions make it impossible to assess whether the reported 29 dB represents a statistically meaningful improvement over the fabrication variables explored.
minor comments (2)
  1. Notation for the coating (PEI/RGO)n should be defined on first use and kept consistent throughout.
  2. Figure captions should explicitly state the number of independent samples measured and whether error bars represent standard deviation or range.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their careful reading and constructive comments. We address each major comment below and have revised the manuscript to address the concerns.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The headline claim that 29 dB at 6 μm and 19 vol.% exceeds prior reports for thicker films with higher loadings is load-bearing for the paper’s contribution, yet the abstract (and presumably the results section) provides neither error bars on the SE value, repeated-measurement statistics, nor the exact frequency band and test geometry (waveguide vs. free-space) used. Without these, direct numerical comparison to literature values cannot be verified.

    Authors: We agree that these details are necessary to support the central claim. We have revised the abstract to report the SE value with error bars from repeated measurements and to specify the frequency band and test geometry. The same information has been added to the results section for clarity. revision: yes

  2. Referee: [Abstract] Abstract / Experimental section: The 19 vol.% RGO loading is stated without describing the determination method (mass balance after deposition, TGA, density measurement, or cross-sectional image analysis). Because the superiority claim rests on achieving high SE at comparatively low loading, an unvalidated vol.% figure undermines the central performance comparison.

    Authors: We agree that the method used to determine the 19 vol.% RGO loading must be explicitly described. We have added this description to the experimental section of the revised manuscript. revision: yes

  3. Referee: [Abstract] Abstract: No baseline data (uncoated substrate SE, pure PEI SE, or single-layer controls) or statistical analysis of the SE versus thickness/loading trends are mentioned. These omissions make it impossible to assess whether the reported 29 dB represents a statistically meaningful improvement over the fabrication variables explored.

    Authors: We agree that baseline data and statistical analysis are important for evaluating the trends. We have added baseline SE measurements for the uncoated substrate and pure PEI coatings, together with statistical analysis of the SE versus thickness and loading trends, to the results section of the revised manuscript. revision: yes

Circularity Check

0 steps flagged

No circularity; experimental EMI SE values reported directly from measurements.

full rationale

This is a purely experimental paper on fabrication and measurement of LbL coatings. The abstract and text describe spray deposition, structural characterization, and direct EMI SE measurements (e.g., 29 dB for 6 μm coating at 19 vol.% loading). No equations, fitted parameters, predictions, or derivation chains appear. The comparison to prior literature is external benchmarking, not a self-referential reduction. No self-citations are invoked as load-bearing uniqueness theorems or ansatzes. The result is self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

This is an experimental materials fabrication and characterization study; the central claims rest on measured physical properties rather than mathematical derivations or postulated entities.

pith-pipeline@v0.9.0 · 5819 in / 1176 out tokens · 41470 ms · 2026-05-25T16:19:03.107517+00:00 · methodology

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Reference graph

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