\makeatletter \@ifundefined{HCode} {\documentclass[screen,CRCHIM,Unicode,biblatex,published]{cedram} \addbibresource{crchim20241025.bib} \newenvironment{noXML}{}{} \def\tsup#1{$^{{#1}}$} \def\tsub#1{$_{{#1}}$} \def\ndash{\text{--}} \usepackage[T1]{fontenc} \def\thead{\noalign{\relax}\hline} \def\tbody{\noalign{\relax}\hline} \def\endthead{\noalign{\relax}\hline} \def\xxtabnote#1{\vskip4pt\parbox{.65\linewidth}{#1}} \def\tabnote#1{\vskip4pt\parbox{.88\linewidth}{#1}} \def\ttabnote#1{\vskip4pt\parbox{.92\linewidth}{#1}} \def\xxxtabnote#1{\vskip4pt\parbox{.95\linewidth}{#1}} \RequirePackage{etoolbox} \def\jobid{crchim20241025} %\graphicspath{{/tmp/\jobid_figs/web/}} \graphicspath{{./figures/}} \newcounter{runlevel} \let\MakeYrStrItalic\relax \csdef{Seqnsplit}{\\} \def\refinput#1{} \def\back#1{} \def\botline{\\\hline} \def\dollar{\$} \def\og{\guillemotleft} \def\fg{\guillemotright} \def\mn{\phantom{$-$}} \def\0{\phantom{0}} \usepackage{multirow} \def\nrow#1{\@tempcnta #1\relax% \advance\@tempcnta by 1\relax% \xdef\lenrow{\the\@tempcnta}} \def\morerows#1#2{\nrow{#1}\multirow{\lenrow}{*}{#2}} \usepackage{hyperref} \def\Lbreak{\newline} \makeatletter \g@addto@macro{\UrlBreaks}{\UrlOrds} \gappto{\UrlBreaks}{\UrlOrds} \DOI{10.5802/crchim.418} \datereceived{2024-12-08} \dateaccepted{2025-09-04} \ItHasTeXPublished } {\documentclass[crchim]{article} \usepackage[T1]{fontenc} \def\CDRdoi{10.5802/crchim.418} \let\refinput\input \makeatletter \let\splittabular\relax \def\xxtabnote#1{\tabnote{#1}} \def\xxxtabnote#1{\tabnote{#1}} \def\ttabnote#1{\tabnote{#1}} } \makeatother \usepackage{upgreek} \dateposted{2025-11-19} \begin{document} \begin{noXML} \CDRsetmeta{articletype}{research-article} \title{Smart fabric using continuous deposition of graphene and aniline, application to electromagnetic shielding} \alttitle{Tissu intelligent utilisant le d\'{e}p\^{o}t continu de graph\`{e}ne et d'aniline, application au blindage \'{e}lectromagn\'{e}tique} \author{\firstname{Mourad} \lastname{Makhlouf}\CDRorcid{0000-0002-6157-5073}\IsCorresp} \address{Scientific and Technological Research Directorate, Cherchell Academy DPHB, 42000, Tipaza, Algeria} \address{Laboratory of Energy Processes and Nanotechnology, University of Blida, Algeria} \email[M. Makhlouf]{makhlouf.amc@gmail.com} \author{\firstname{Sabrina} \lastname{Bouriche}\CDRorcid{0009-0000-0037-1168}} \addressSameAs{2}{Laboratory of Energy Processes and Nanotechnology, University of Blida, Algeria} \author{\firstname{Zoubir} \lastname{Benmaamar}\CDRorcid{0000-0001-9469-7301}} \addressSameAs{2}{Laboratory of Energy Processes and Nanotechnology, University of Blida, Algeria} \author{\firstname{Didier}\nobreakauthor\lastname{Villemin}\CDRorcid{0000-0002-6266-3817}} \address{Laboratory of Molecular and Thio-organic Chemistry, UMR CNRS 6507, INC3M, FR 3038, ENSICAEN and Research Center, University of Caen, France} \shortrunauthors %\def\thanksname{} %\thanks{} \keywords{\kwd{Cotton fabric} \kwd{Graphene} \kwd{Polyaniline} \kwd{Electromagnetic shielding} \kwd{Conductivity} \kwd{Recycling}} \altkeywords{\kwd{Tissu en coton} \kwd{Graph\`{e}ne} \kwd{Polyaniline} \kwd{Blindage \'{e}lectromagn\'{e}tique} \kwd{Conductivit\'{e}} \kwd{Recyclage}} \begin{abstract} This study presents the development of conductive textiles for effective electromagnetic interference (EMI) shielding, achieved through the modification of cotton fabric with graphene and polyaniline. Graphene, obtained by electrochemical exfoliation of recycled graphite from spent batteries, and polyaniline, synthesized in situ using hydrogen peroxide as a novel oxidant, were selectively deposited on the cotton fibers to ensure strong adhesion and uniform dispersion. The electrical conductivity and EMI shielding effectiveness (SE) of the modified fabrics were evaluated in the 8--9 GHz frequency range as a function of nanofiller content. Experimental results showed excellent electrical conductivity and significant EMI shielding performance, with a maximum SE value of 15.4 dB. The synergistic conductive network formed by the integration of electrochemically exfoliated graphene and chemically synthesized polyaniline played a critical role in enhancing the electromagnetic wave attenuation. This work demonstrates a sustainable approach for the preparation of high-performance EMI shielding textiles using recycled materials and a novel synthesis route, and demonstrates the potential of graphene and polyaniline as effective conductive nanofillers for advanced EMI shielding applications. \vspace*{-2pt} \end{abstract} \begin{altabstract} Cette \'{e}tude pr\'{e}sente le d\'{e}veloppement de textiles conducteurs pour un blindage efficace contre les interf\'{e}rences \'{e}lectromagn\'{e}tiques (EMI), obtenu par la modification d'un tissu de coton avec du graph\`{e}ne et de la polyaniline. Le graph\`{e}ne, obtenu par exfoliation \'{e}lectrochimique de graphite recycl\'{e} provenant de batteries usag\'{e}es, et la polyaniline, synth\'{e}tis\'{e}e in situ en utilisant le peroxyde d'hydrog\`{e}ne comme nouvel oxydant, ont \'{e}t\'{e} d\'{e}pos\'{e}s s\'{e}lectivement sur les fibres de coton pour assurer une forte adh\'{e}rence et une dispersion uniforme. La conductivit\'{e} \'{e}lectrique et l'efficacit\'{e} de blindage (SE) EMI des tissus modifi\'{e}s ont \'{e}t\'{e} \'{e}valu\'{e}es dans la gamme de fr\'{e}quences 8--9 GHz en fonction de la teneur en nanocharges. Les r\'{e}sultats exp\'{e}rimentaux ont montr\'{e} une excellente conductivit\'{e} \'{e}lectrique et une performance de blindage EMI significative, avec une valeur maximale de SE de 15,4 dB. Le r\'{e}seau conducteur synergique form\'{e} par l'int\'{e}gration du graph\`{e}ne exfoli\'{e} \'{e}lectrochimiquement et de la polyaniline synth\'{e}tis\'{e}e chimiquement a jou\'{e} un r\^{o}le essentiel dans l'am\'{e}lioration de l'att\'{e}nuation des ondes \'{e}lectromagn\'{e}tiques. Ce travail d\'{e}montre une approche durable pour la pr\'{e}paration de textiles de blindage EMI haute performance en utilisant des mat\'{e}riaux recycl\'{e}s et une nouvelle voie de synth\`{e}se, et met en \'{e}vidence le potentiel du graph\`{e}ne et de la polyaniline en tant que nanocharges conductrices efficaces pour des applications avanc\'{e}es de blindage EMI. \end{altabstract} \maketitle \twocolumngrid \end{noXML} \section{Introduction}\label{sec1} Textile engineers can design fabrics with electromagnetic shielding properties, which are particularly valuable in aerospace, military, and medical applications. Electrically conductive fabrics offer excellent electromagnetic interference (EMI) shielding capabilities, making them suitable for a wide range of uses~\cite{1}. Krishnasamy et~al.~\cite{2} have developed and characterized various EMI shielding materials, including textiles, designed to protect against radio waves, radar signals, and other forms of electromagnetic energy. Rube\v{z}ien\.{e} et~al.~\cite{3} demonstrated that the distribution and thickness of poly (3,4-ethylenedioxythiophene) (PEDOT) coatings significantly influence the shielding effectiveness (SE) of textiles. These fabrics represent a promising approach to electromagnetic shielding, with a clear correlation established between their electrostatic properties and shielding performance. Patel et~al.~\cite{4} provide a comprehensive analysis of recent advancements in photocatalytic, super-hydrophobic, and EMI shielding textile treatments using nanomaterials. While these developments offer significant advantages for both users and manufacturers, it is crucial to address the challenges and limitations associated with the integration of nanomaterials. The SE of treated fabrics depends on the fabric's geometry and the quantity of metal present. Such textiles can be used as protective workwear to shield individuals from electromagnetic radiation or as covers to block electromagnetic fields~\cite{5}. Recent research has focused on innovative strategies, primarily based on passive textile designs, to enhance thermal conductivity~\cite{6}. Shukla et~al.~\cite{7} optimized the thickness of a carbon layer to develop a porous Fe$_{3}$O$_{{4}}$/C shell, achieving an electromagnetic wave attenuation of 38.8 dB at a thickness of 2.1 mm. Guo et~al.~\cite{8} successfully created novel graphene-based foams that are remarkably lightweight (0.011~g/cm$^3$) and exhibit exceptional electromagnetic wave attenuation capabilities. These foams demonstrate an average attenuation of 37.2 dB with a graphene loading of just 0.105{\%}, highlighting their impressive SE. According to Liu et~al.~\cite{9}, increasing the content of functional particles (such as graphite, graphene, and silver-coated copper powder) up to 60{\%} within the frequency range of 0.01--3.0 GHz optimizes the shielding properties of the coating. However, exceeding this threshold may degrade absorption capabilities due to the formation of conductive structures that alter the material's dielectric properties. The resulting graphene nanosheet (GNS)/water-based polyurethane (WPU) composites exhibit exceptional EMI shielding performance, achieving approximately 32 dB while maintaining flexibility and lightweight characteristics. Notably, these composites demonstrate high electrical conductivity, reaching 5.1 S/m at a low GNS content of 5{\%} by volume (approximately 7.7{\%} by weight)~\cite{10}. Sol--gel and in situ polymerization are the most commonly employed methods for ferrite fabrication. Polyaniline (PANI) nanocomposites, created by combining ferrite nanoparticles with PANI, show promising properties for EMI shielding~\cite{11}. Avloni et~al.~\cite{12} demonstrated that fabrics coated with polypyrrole (PPy) provide effective electromagnetic shielding (37 dB), comparable to other conductive polymers. These fabrics allow precise tuning of surface resistivity, enabling control over their SE. Akif Kaynak's research~\cite{13} further underscores the \mbox{excellent} electromagnetic shielding capabilities of PPy-coated textiles. These findings highlight that conductive textiles based on polymers are lightweight, high-performance shielding materials, opening new opportunities in this field. Graphene-based composites are also widely used in biological applications, including tissue engineering, drug and gene delivery, and bioimaging. Table~\ref{tab1} summarizes the remarkable properties and diverse applications of various graphene-based composites in tissue engineering. %tab1 \begin{table*} \caption{\label{tab1}Properties and diverse applications of various graphene-based composites in tissue engineering} \begin{tabular}{llllc} \thead Composite & Production & Effects & Applications & Ref. \vspace*{3pt}\\ \endthead PLA/GO & \parbox[t]{3.5cm}{\raggedright Fused deposition modeling} & \parbox[t]{5.5cm}{\raggedright Increase mechanical properties, benefit cell proliferation} & Tissue engineering & \cite{14} \\ PLA/PU & - &\parbox[t]{5.5cm}{\raggedright Remarkable improvement in antibacterial capacity} & Tissue engineering & \cite{15} \\ TCP/PLA & - & \parbox[t]{5.5cm}{\raggedright Showing swelling profile, improved biomineralization capacity, and alkaline phosphatase (ALP) activity} & Tissue engineering & \cite{16} \\ PE/rGO & - & \parbox[t]{5.5cm}{\raggedright High mechanical strength, thermal stability, electrical property, and antibacterial capacity} & Tissue engineering & \cite{17}\\ Gr-ZnO & \parbox[t]{3.5cm}{\raggedright Depositing zinc oxide on graphene nanosheet surfaces} & \parbox[t]{5.5cm}{\raggedright Exhibit superior antimicrobial effects} & Tissue engineering & \cite{18,19}\vspace*{2pt} \botline \end{tabular} \end{table*} The table highlights the potential of graphene in tissue engineering by combining it with other materials to create composites with enhanced mechanical properties, antibacterial characteristics, and improved biomineralization capacity, among other benefits. These attributes are particularly relevant for developing materials designed to interact with living tissues, such as implants or scaffolds for tissue regeneration~\cite{20}. The primary objective of our work is to develop high-performance smart textiles specifically designed to provide enhanced protection for humans against the harmful effects of electromagnetic waves. To achieve this, we have developed an innovative process for functionalizing fabrics using nanomaterials, particularly graphene obtained through the electrochemical exfoliation of recycled graphite from spent batteries. Simultaneously, we synthesized a conductive polymer, polyaniline, using a novel alternative oxidant, hydrogen peroxide. By integrating these two nanomaterials into textile fibers, we have created composite materials that exhibit excellent electrical conductivity and significant electromagnetic shielding capabilities, particularly within the 8--9 GHz frequency range. \section{Experimental}\label{sec2} \subsection{Preparation of graphene}\label{sec21} We employed an electrochemical method to exfoliate graphite rods into graphene using a sulfuric acid electrolyte. In this study, electrochemical exfoliation was carried out using graphite rods sourced from electrical battery units, which served as the electrodes, along with a container filled with a mixture of H$_{{2}}$SO$_{{4}}$ and H$_{{2}}$O as the electrolyte. This process yielded high-performance, large-area thin graphene sheets. The presence of graphene in the synthesized material was confirmed using advanced characterization techniques, including Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), BET (Brunauer--Emmett--Teller) surface area analysis, Fourier transform infrared spectroscopy (FT-IR), and X-ray fluorescence analysis (XRF)~\cite{21,22,23}. \section{Preparation of polyaniline}\label{sec22} The standard method for preparing polyaniline (PANI) involves the chemical polymerization of aniline in an acidic environment, using an oxidant as a catalyst. This process results in the formation of a polymeric chain composed of repeating aniline units, which can exist in various oxidation states depending on the synthesis conditions. The production protocols for PANI vary based on factors such as operating conditions, including temperature and pH of the reaction medium~\cite{24}. Table~\ref{tab2} summarizes the different PANI synthesis protocols. %tab2 \begin{table*} \caption{\label{tab2}Production protocol for PANI} \begin{tabular}{llllc} \thead Composite name & Preparation method & Properties & Application & Ref. \\ \endthead \parbox[t]{3.2cm}{\raggedright PANI/graphite} & \parbox[t]{4cm}{\raggedright In situ chemical oxidative polymerization} & \parbox[t]{2.5cm}{\raggedright Increased thermal stability} & \parbox[t]{3cm}{\raggedright Antistatic coating} & \cite{25} \\ \parbox[t]{3.2cm}{\raggedright PANI/exfoliated graphene} & \parbox[t]{4cm}{\raggedright In situ chemical oxidative polymerization} & \parbox[t]{2.5cm}{\raggedright Better cyclic stability} & \parbox[t]{3cm}{\raggedright Supercapacitor and sodium battery cathode} & \cite{26} \\ \parbox[t]{3.2cm}{\raggedright PANI/magnetic graphene} & \parbox[t]{4cm}{\raggedright Hydrothermal method} & \parbox[t]{2.5cm}{\raggedright High sensitivity} & \parbox[t]{3cm}{\raggedright Biosensors} & \cite{27} \\ \parbox[t]{3.2cm}{\raggedright PANI/graphene oxide} & \parbox[t]{4cm}{\raggedright Precipitation polymerization} & \parbox[t]{2.5cm}{\raggedright Good selectivity} & \parbox[t]{3cm}{\raggedright Electrochemical sensor} & \cite{28} \\ \parbox[t]{3.2cm}{\raggedright PANI/reduced graphene oxide} & \parbox[t]{4cm}{\raggedright In-situ interfacial polymerization method} & \parbox[t]{2.5cm}{\raggedright Excellent mechanical properties} & \parbox[t]{3cm}{\raggedright Anticorrosion, antistatic, and antibacterial applications} & \cite{29}\\ \parbox[t]{3.2cm}{\raggedright Graphene oxide/PANI manganese oxide} & \parbox[t]{4cm}{\raggedright In situ chemical oxidative polymerization} & \parbox[t]{2.5cm}{\raggedright Synergic behavior of PANI} & \parbox[t]{3cm}{\raggedright Adsorbent application} & \cite{30} \\ \parbox[t]{3.2cm}{\raggedright SnO$_{2}$/reduced graphene oxide/PANI} & \parbox[t]{4cm}{\raggedright In situ chemical oxidative polymerization} & \parbox[t]{2.5cm}{\raggedright Improved chemical stability} & \parbox[t]{3cm}{\raggedright Ammonia gas sensing} & \cite{31} \\ \parbox[t]{3.2cm}{\raggedright PANI/graphene obtained by recycling graphite from spent batteries} & \parbox[t]{4cm}{\raggedright In situ chemical oxidative with H$_{2}$O$_{2}$ polymerization} & \parbox[t]{2.5cm}{\raggedright Good screen against EMI} & \parbox[t]{3cm}{\raggedright Continuous dyeing for intelligent fabrics} & This work\vspace*{3pt} \botline \end{tabular} \vspace*{-3pt} \end{table*} The synthesis protocol for PANI comprised three essential steps: \subsection{Pretreatment of monomer (aniline)}\label{sec23} To prevent side reactions and enhance polymerization yield, aniline (analytical grade, Merck) was purified using vacuum distillation. The purified aniline was then stored in a cool, dark environment. \subsection{Protonation of aniline monomer}\label{sec24} \vspace*{-2pt} As PANI is a base-conjugated semiconductor, the dopant plays a critical role during polymerization. To initiate the reaction, 50 mL of hydrochloric acid (HCl, 37{\%}) was added dropwise to purified aniline under continuous mechanical stirring for one hour. This step facilitates the cleavage of N--H and N--C bonds in aniline, enabling the attachment of protons (H$^+$) to nitrogen atoms, which act as polymerization initiators in the presence of an oxidant. \vspace*{-2pt} \subsection{Polymerization}\label{sec25} \vspace*{-2pt} Following protonation, polymerization was initiated by slowly adding hydrogen peroxide (H$_2$O$_2$) as the oxidant dropwise over 4--6~h. The oxidant-to-monomer ratio ([H$_2$O$_2$]/[aniline]) was maintained at 1.15, and the reaction temperature was held at ${-}$5~\textdegree C. The resulting dark green PANI powder was filtered under vacuum, washed sequentially with 0.1 N HCl, methanol, and deionized water, and dried in an oven at 60~\textdegree C for 24~h. \vspace*{-2pt} \section{Continuous dyeing process}\label{sec3} \vspace*{-2pt} Two dispersions were prepared: (G) Graphene dispersion: 1 g of graphene was dispersed in 100 mL of distilled water and sonicated for 1 h; (PANI) Polyaniline dispersion: 1~g of PANI was dispersed in 100 mL of acetic acid and sonicated for 1~h. Both dispersions were simultaneously applied to a plain-weave cotton fabric (properties listed in Table~\ref{tab3}), yielding three samples: T/G: Fabric coated with graphene. T/PANI: Fabric coated with polyaniline. T/G/PANI: Fabric coated with graphene and polyaniline. %tab3 \begin{table*} \caption{\label{tab3}Characteristics of the cotton fabric\vspace*{-1pt}} \begin{tabular}{llllll} \thead Characteristic & \parbox[t]{2.5cm}{\raggedright Weave structure} & \parbox[t]{2.5cm}{\raggedright Warp and weft density} & \parbox[t]{2.5cm}{\raggedright Thread count} & Weight & \parbox[t]{1.5cm}{\raggedright Hand feel}\vspace*{2pt} \\ \endthead Value & Plain-weave & \parbox[t]{2.5cm}{\raggedright 100 threads per inch (TPI)} & \parbox[t]{2.8cm}{\raggedright Approximately 60 threads per inch} & \parbox[t]{2.2cm}{\raggedright Approximately 150 g/m$^{2}$} & Soft \vspace*{2pt} \botline \end{tabular} \vspace*{-1pt} \end{table*} \subsection{Conductivity measurement}\label{sec41} To measure conductivity, a PANI sample was prepared as a film or pellet. Two electrodes were connected to the sample, and a voltage was applied across it. The conductivity $(\sigma )$ of the sample was calculated using the formula: {$$ \sigma = 1/\rho \times t/A $$}\unskip where $\rho$ is the resistivity, $t$ is the thickness of the sample, and $A$ is the cross-sectional area. The conductivity of PANI can vary significantly depending on factors such as the synthesis method, doping level, and sample purity. The conductivity of various materials is summarized in Table~\ref{tab4}. %tab4 \begin{table} \caption{\label{tab4}Conductivity of various materials} \begin{tabular}{ccc} \thead Material & \parbox[t]{2cm}{\centering Conductivity (S${\cdot}$cm$^{-1}$)} & Ref. \vspace*{3pt}\\ \endthead Silver, gold, iron & ${\sim}10^{5}$ & \morerows{4}{\cite{32}} \\ Silicon, germanium & ${\sim}10^{1}$ & \\ Doped polyaniline & ${\sim}10^{1}$ & \\ Undoped polyaniline & ${\sim}10^{-8}$ & \\ Nylon & ${\sim}10^{-14}$ & \\ PANI & 4.$7\times 10^{-1}$ & This work \botline \end{tabular} \end{table} \subsection{Structural characterization by FT-IR}\label{sec42} During FT-IR analysis, PANI is exposed to infrared radiation, which causes the polymer's chemical bonds to absorb specific wavelengths of the radiation. The resulting spectrum reveals absorption frequencies that correspond to vibrational modes of functional groups within PANI. These vibrational modes are compared to standard reference bands to identify functional groups and confirm their presence in the polymer structure. The FT-IR spectrum of the as-synthesized PANI is shown in Figure~\ref{fig1}. A quinoid-ring stretching vibration appears as a band at about 1560 cm$^{{-1}}$, and the peak around 1325 cm$^{{-1}}$ is attributed to the C--N stretching vibration between the benzenoid and quinoid units~\cite{33}. The band at 1475 cm$^{{-1}}$ is due to the C--C stretching vibration in the benzene ring. Another peak appears around 1290 cm$^{{-1}}$, associated with the delocalization of $\uppi $-electrons due to protonation or C--N stretching vibration, while a high absorption band near 1246 cm$^{{-1}}$ is observed due to the deformation of the polaron structure from the C--N stretching mode~\cite{34,35}. The band between 1145 and 1601 cm$^{{-1}}$ corresponds to in-plane C--H bending (N${=}$Q${=}$N and B--NH$^{{+}}$--B where Q ${=}$ NH$^{{+}}$--B and B represents the aromatic ring) resulting from protonation~\cite{36}. Researchers refer to this as the ``electronic-like band'', indicating electron delocalization in PANI~\cite{37}. In addition, the peak at 1090 cm$^{{-1}}$ is attributed to the in-plane bending of aromatic C--H in the 1,4-disubstituted aromatic ring~\cite{38}. Researchers have identified the band at 860 cm$^{{-1}}$ as the out-of-plane bending vibration mode of C--H, as previously discussed for single-walled carbon nanotubes (SWCNTs)~\cite{39}. The band at 640~cm$^{{-1}}$ corresponds to the S--O stretching vibration of sulfonate substituents in aromatic rings, indicating that PANI nanotubes have been doped~\cite{40}. The characteristic bands are \mbox{consistent} for all PANI salts, confirming the presence of the emeraldine salt phase in each compound~\cite{41}. The differences in the intensities of the 1350--1000 cm$^{{-1}}$ peaks among the PANI salts can be explained by the different degrees of protonation~\cite{42}. \begin{figure} \includegraphics{fig01} \caption{\label{fig1}Fourier transform infrared (FTIR) spectrum of the conducting polyaniline (PANI).} \end{figure} \subsection{Contact angle measurement}\label{sec43} Contact angle measurements are used to characterize the hydrophilic/hydrophobic nature of a material, enabling the evaluation of the influence of nanofillers on the wetting properties of the fabric~\cite{43,44}. This technique involves depositing a liquid droplet onto the fabric and measuring the angle formed between the tangent to the droplet surface and the solid surface at any point during the process. This angle, known as the contact angle or sessile angle, describes the interaction between the liquid, solid, and air~\cite{45}. We characterized the shape of the droplets at equilibrium on our substrates using the sessile-drop method and imaging software (Figure~\ref{fig2}). \begin{figure*} \includegraphics{fig02} \caption{\label{fig2}Contact angle degrees: (T) fabric 66.749\textdegree, (T/PANI) fabric coated with polyaniline 137.643\textdegree, (T/G/PANI) fabric coated with graphene and polyaniline 108.635\textdegree.} \end{figure*} The researchers used these measurements to determine whether the modified fabric exhibited hydrophilic or hydrophobic properties. The contact angles of the samples are summarized in Table~\ref{tab5}. %tab5 \begin{table*} \caption{\label{tab5}Contact angles of our samples} \begin{tabular}{cccc} \thead Fabric type & Contact angle & Interval of young & Nature of sample\\ \endthead T & \066.749 & $\upalpha <90$ & Hydrophilic \\ T/PANI & 137.643 & $90<\upalpha<150$ & Hydrophobic\\ T/G/PANI & 108.635 & $90<\upalpha<150$ & Hydrophobic \botline \end{tabular} \end{table*} Our observation was that the contact angle increased with the conductivity of the coating filler, indicating a trend toward a more hydrophobic surface. This shift toward hydrophobicity suggests a change in the surface's polar characteristics. Generally, hydrophilic surfaces (low contact angles) are more polar, exhibiting stronger interactions with \mbox{polar} liquids like water through hydrogen bonding and dipole--dipole interactions. Conversely, \mbox{hydrophobic} \mbox{surfaces} (high contact angles) are typically less polar, with weaker interactions with water, favoring interactions through London dispersion forces. Therefore, our finding that higher conductivity fillers led to higher contact angles implies that these fillers, when integrated into the fabric, resulted in a less polar surface. This could be attributed to the nature of the conductive materials used---graphene and polyaniline---which, in their deposited form, present a less polar surface compared to the untreated fabric. \section{Shielding effectiveness}\label{sec5} A network analyzer is an instrument used to characterize devices in microwave circuits, such as amplifiers, attenuators (both fixed and variable), and cables, among others. It integrates the system and evaluates its impact on signal transmission or reception. This instrument enables the quantification of the S-parameters (short for scattering parameters). These parameters provide critical information, including power, gain and/or attenuation, return loss, and impedance. The rectangular waveguide, based on a quadrupole structure, is a technique used to determine key parameters such as the reflection coefficient and transmission coefficient using a network analyzer. To measure the electromagnetic shielding effectiveness (SE), we placed fabric samples into the waveguide support of a Keysight N5222A vector network analyzer, as illustrated in Figure~\ref{fig3}. \begin{figure*} \vspace*{-2pt} \includegraphics{fig03} \vspace*{-3pt} \caption{\label{fig3}(a) Sample holder; (b) Fabrics (4 cm$^{2}$); (c) Waveguide holder; (d) Vector network analyzer.} \vspace*{-3pt} \end{figure*} The SE experiments were conducted within the frequency range of 8--9~GHz, which is commonly used in both military and civilian communications. Using a two-port vector network analyzer, the S-parameters were measured and analyzed. These parameters are defined as: $S_{11}=b_1/a_1$ (reflection coefficient), $S_{21}=b_2/a_1$ (transmission coefficient), where $a$ and $b$ represent the normalized incident and reflected waves, respectively. The process involves measuring the reflected signal ($S_{11}$) and the transmitted signal ($S_{21}$), as well as calculating the absorbance using the following equations: {\begin{eqnarray} \mbox{Transmittance }T &=& | S_{21}|^2 \label{eq1}\Seqnsplit \mbox{Reflection }R &=& | S_{11}|^2 \label{eq2}\Seqnsplit \mbox{Absorbance }A &=& 1-R -T \label{eq3}\Seqnsplit \mbox{SER }&=& 10{\cdot}\log_{10}(1-R) \label{eq4}\Seqnsplit \mbox{SEA }&=& 10{\cdot}\log_{10}|T/(1-R)| \label{eq5}\Seqnsplit \mbox{SE }&=& \mbox{SER} + \mbox{SEA} \label{eq6} \end{eqnarray}}\unskip We calculate the SEA and the SER of each sample by measuring the $S_{{11}}$ and $S_{{21}}$ parameters of our various samples using a vector network analyzer. \mbox{Figures~\ref{fig4}} and~\ref{fig5} present the results of the SE measurements, illustrating the variation in the effectiveness of the shielding for reflection SER and absorption SEA. It is evident from the plots that the SEA and SER values exhibit a proportional relationship with the frequency at low frequencies, as well as with the type of nanofiller added. Furthermore, the addition of conductive nanofillers primarily contributes to the increases in SEA and SER. The purpose of these tests was to evaluate the electromagnetic SE and obtain values for S-parameters $S_{{11}}$ (reflected incident) and $S_{{21}}$ (transmitted incident). These findings indicate that the SE of the composite fabrics increases with a higher surface conductive charge. For instance, a fabric coated with graphene displayed $S_{{21}}$ and $S_{{11}}$ (S-parameters) values of 5.2 and 10.95 dB, respectively, compared to 9.2 and 7.24 dB for a PANI-coated fabric. On the other hand, a fabric coated with both PANI and graphene displayed $S_{{21}}$ and $S_{{11}}$ values of 11.9 and 10.24 dB, respectively. The increase in conductive loading also led to an increase in the $S_{{21}}$ transmission parameter from 3.15 dB (fabric) to 5.2 dB (graphene-coated fabric), 9.2 dB (PANI-coated fabric), and 11.9 dB (T/G/PANI). In addition, the $S_{{11}}$ reflection parameter increased from 5.2 dB (fabric) to 10.24 dB (graphene and PANI-coated fabric). The S-parameters of different fabrics are summarized in {Table~\ref{tab6}}.\looseness=-1 \begin{figure} \includegraphics{fig04} \caption{\label{fig4}Shielding effectiveness for reflection (SER) in the 8--9~GHz range.} \vspace*{-2pt} \end{figure} \begin{figure} \vspace*{-1pt} \includegraphics{fig05} \vspace*{-3pt} \caption{\label{fig5}Shielding effectiveness for absorption (SEA) in the 8--9~GHz range.} \end{figure} %tab6 \begin{table} \caption{\label{tab6}S-parameters of different fabrics\vspace*{-3pt}} \begin{tabular}{ccc} \thead {Fabric} & $S_{21}$ {(dB)} & $S_{11}$ (dB) \\ \endthead T/G & {\05.2} & {10.95} \\ T/PANI & {\09.2} & {\07.24} \\ T/G/PANI & {11.9} & {10.24} \botline \end{tabular} \vspace*{-3pt} \end{table} %tab7 \begin{table*} \caption{\label{tab7}EMI shielding effectiveness of carbon-coated fabrics\vspace*{-1pt}} \begin{tabular}{ccccccccc} \thead Substrates & Medication routes & Carbon-based materials & EMI SE (dB) & Ref.\vspace*{3pt} \\ \endthead Cotton & Dip-drying process & MWCNTs$^{\mathrm{a}}$ & \09.0 & \cite{46} \\ Vinylon & Blade coating method & Graphite nanosheets & 28.0 & \cite{47} \\ Polyester & Pad-dry-cure method & Nano carbon black & \07.7 & \cite{48} \\ Polyester & Plasma-assisted dip-drying & NH$_{2}$--MWCNTs & 18.2 & \cite{49} \\ Cotton & Knife-over-roll coating & Carbon black & 31\0 & \cite{50} \\ Nonwoven fabric & Knife-over-roll coating & Graphene nanotube & 15\0 & \cite{51} \\ Cotton & Continuous dyeing & Graphene ${+}$ PANI & 15.4 & This work \botline \end{tabular} \tabnote{$^{\mathrm{a}}$Multiwall carbon nanotubes.} \end{table*} %tab8 \begin{table*} \caption{\label{tab8}Microwave absorption properties of various PANI-based composites} \begin{tabular}{ccccc} \thead Absorber & Thickness (mm) & Max RL (frequency) & Bandwidth (GHz) & Ref. \\ \endthead PANI nanoparticles & 2.0 & 18.8~dB (17.2~GHz ) & 14.1--18.0 & \cite{52} \\ BaFe$_{12}$O$_{19}$/PANI & 2.0 & 19.7~dB (14.6~GHz) & 13.0--16.9 & \cite{53} \\ Ba(CoTi)$_{x}$Fe$_{12-2x}$O$_{19}$/PANI & 2.0 & 33.7~dB (14.6~GHz) & 12.0--17.3 & \cite{54} \\ Fe$_{3}$O$_{4}$ microspheres/PANI & 2.0 & 18.6~dB (14.0~GHz) & 12.1--16.0 & \cite{55} \\ Fe$_{3}$O$_{4}$/MWCNT/PANI & 2.0 & 8.0~dB (14.7~GHz) & Undetected & \cite{56} \\ graphite/CoFe$_{2}$O$_{4}$/PANI & 2.0 & 11.0~dB (3.8~GHz) & 3.4--4.0& \cite{57} \\ graphene/PANI & 2.0 & 25.3~dB (16.5~GHz) & 13.9--18.0 & \cite{58} \\ ${\upalpha}$-MoO$_{3}$/PANI & 2.0 & 33.7~dB (16.9~GHz) & 14.2--18.0& \cite{59} \\ Fe$_{3}$O$_{4}$/PANI & 2.0 & 13.8~dB (16.7~GHz) & 16.3--17.2 & \cite{60} \\ Fe$_{3}$O$_{4}$ microspheres/PANI & 2.0 & 37.4~dB (15.4~GHz) & 13.0--18.0 & \cite{61} \\ NiZn ferrite/PANI & 2.0 & 20.0~dB (14.0~GHz) & 12.0--16.6 & \cite{62} \\ Fe$_{3}$O$_{4}$/CIP/PANI & 2.0 & 25.5~dB (10.1~GHz) & 7.1--9.9 & \cite{63} \\ BaTiO$_{3}$/PANI & 2.0 & 13.8~dB (11.6~GHz) & 10.7--12.5 & \cite{64} \\ MnO$_{2}$/PANI & 2.0 & 20.9~dB (13.5~GHz) & 11.4--16.8 & \cite{65}\\ graphene@Fe$_{3}$O$_{4}$@SiO$_{2}$@PANI & 2.0 & 19.4~dB (16.4~GHz) & 10.4--18.0 & \cite{66} \\ Ni/C/PANI & 2.0 & 7.5~dB (10.0~GHz) & Undetected & \cite{67} \\ PPy@PANI-0.8 & 2.0 & 23.3~dB (15.8~GHz) & 13.5--18.0 &\morerows{2}{\cite{68}} \\ PPy@PANI-1.2 & 2.0 & 34.8~dB (13.9~GHz) & 11.9--16.6 & \\ PPy@PANI-1.6 & 2.0 & 31.5~dB (13.6~GHz) & 11.7--16.4 & \\ Textile & 2.0 & 9.53~dB (8.17~GHz) & \morerows{3}{8--9} &\morerows{3}{This work} \\ Textile/Graphene & 2.0 & 11.17~dB (8.17~GHz) & & \\ Textile/PANI & 2.0 & 9.98~dB (8.17~GHz) & & \\ Textile/Graphene/PANI & 2.0 & 15.4~dB (8.17~GHz) & & \botline \end{tabular} \end{table*} However, the PANI/G composite fabric showed a lower $S_{{11}}$ reflection parameter of 10.24 dB compared to the graphene-coated fabric, which had an $S_{{11}}$ value of 10.95 dB~\cite{22}. This decrease can be attributed to the way PANI/graphene is absorbed and retained on the fabric surfaces and within its interstices. Despite this, researchers notably found that all the composite fabrics studied could serve as effective materials for constructing electromagnetic shielding. Figure~\ref{fig6} presents the SE of various samples as a \mbox{function} of frequency within the 8--8.6 GHz range. The data reveals a clear frequency dependence of SE, indicating that both the conductive charge and the specific nature of the fabric's coating significantly influence its shielding capabilities. Table~\ref{tab7} summarizes the electromagnetic interference (EMI) SE of fabrics coated with carbon-based materials. Table~\ref{tab8} lists the electromagnetic SE of some typical PANI-based composites. Max RL (Frequency) refers to the maximum attenuation in decibels (dB), indicating the peak absorption efficiency at a given frequency. Bandwidth (GHz) indicates the frequency range over which absorption exceeds a certain threshold. The results show that the modification of the fabric coating with graphene nanofillers improves SE. The conductive PANI coating on the fabric achieved a SE of 9.98 dB, while graphene used as a coating material increased this effect to 11.17 dB. The effective shielding properties were further improved to a SE of 15.4 dB when the fabric was coated with PANI/graphene. \begin{figure} \includegraphics{fig06} \vspace*{-4pt} \caption{\label{fig6}Electromagnetic shielding effectiveness (SE) for various samples in the 8 to 8.6~GHz range.} \vspace*{-2pt} \end{figure} \vspace*{-4pt} \section{Conclusion}\label{sec6} \vspace*{-3pt} In this work, we report the use of graphene as filler uniformly distributed in the fabric matrix with polyaniline coating to improve its electromagnetic shielding effectiveness up to 15.4 dB from simulation results. The trade-off between the attenuation of electromagnetic waves and reflection loss results in a conductive network with a higher graphene content. Changing the type of carbon nanofillers within the matrix affects the shielding effectiveness, which may be due to the conductivity enhancement in each doped device. \vspace*{-4pt} \section*{Authorship contributions} \vspace*{-3pt} Authors equally contributed to this work. \vspace*{-4pt} \section*{Ethics approval} \vspace*{-3pt} There are no ethical issues with the publication of this manuscript. \vspace*{-4pt} \section*{Data availability statement} \vspace*{-3pt} The authors confirm that the data that supports the findings of this study are available within the article. Raw data that support the findings of this study are available from the corresponding author, upon reasonable request. \section*{Declaration of interests} The authors do not work for, advise, own shares in, or receive funds from any organization that could \mbox{benefit} from this article, and have declared no affiliations other than their research organizations. \back{} \printbibliography \refinput{crchim20241025-reference.tex} \end{document}