Department of Physics, SSA Government First Grade College, Ballari – 583101, India
The significance of low-dimensional, particularly nanosized particles, is underscored by the sol-gel method adopted for the preparation of TiO2. A nanocomposite of TiO2 doped with a PANI-PVA matrix was synthesized using the in-situ polymerization method. The prepared PANI nanocomposite was subjected to Fourier Transform Infrared Spectroscopy (FTIR) to elucidate its structural characteristics, while Scanning Electron Microscopy (SEM) was employed to analyze its surface morphology. The direct current (DC) conductivity measurements indicate that the conductivity of the PANI nanocomposite increases with rising temperature, exhibiting a three-step conductivity behaviour. The real part of permittivity (?') as a function of X-band frequency indicates that the permittivity values of PVA, PANI, and PANI-TiO2 nanocomposites decrease with increasing frequency. The nanocomposite containing 3 wt% TiO2 in the PANI/PVA matrix exhibits a low tangent loss value of 0.34, which decreases to 0.084 as the frequency increases. In the 3 wt% TiO2 PANI-PVA nanocomposites, the reflection loss (RL) peak reaches 16.4 dB at 57.1 GHz, while the electromagnetic interference shielding effectiveness (EMI SE) improves from approximately -35.2 dB for pure PANI to about -55.6 dB for the PANI-PVA-TiO2 nanocomposite. Therefore, the PANI-PVA-TiO2 nanocomposite can be utilized as a shielding material to create a protective surface layer.
The demand for advanced materials in electronics and communication systems continues to grow, making the need for effective electromagnetic interference (EMI) shielding solutions paramount. Among the various materials investigated for this purpose, conducting polymers have garnered significant interest due to their lightweight nature, flexibility, and tunable electrical properties [1]. Electromagnetic interference (EMI) can negatively impact the performance and reliability of electronic circuits, resulting in operational failures and signal degradation. As a result, there is a high demand for effective shielding materials that can mitigate EMI [2]. Among various conductive polymers, polyaniline (PANI) is particularly notable due to its tunable conductivity, environmental friendliness, and ease of synthesis. However, its effectiveness as an EMI shielding material can be significantly enhanced when combined with high-conductivity materials such as carbon nanotubes (CNTs), graphene, and metal oxide nanoparticles. The development of PANI-based composites, especially the PVA-ZnO blend, offers a promising approach to improving electromagnetic interference (EMI) shielding [3]. Polyaniline's intrinsic electrical conductivity and environmental stability make it a prime candidate for electromagnetic interference (EMI) applications. When combined with polyvinyl alcohol (PVA) and zinc oxide (ZnO), the resulting composite can potentially harness the unique properties of each component to enhance shielding effectiveness and improve mechanical properties [4]. Research indicates that polyaniline composites exhibit improved EMI shielding when combined with dielectric materials such as PVA, which enhances the dielectric properties crucial for attenuating electromagnetic waves. One of the primary considerations for any EMI shielding material is its effectiveness in reducing electromagnetic wave transmission [5]. The incorporation of zinc oxide (ZnO) not only enhances the conductivity of the composite but also improves its capacitive and inductive properties, resulting in superior electromagnetic interference (EMI) shielding efficiency. The mechanism of EMI shielding in these composites typically involves the absorption, reflection, and multiple scattering of electromagnetic waves, with enhanced absorption attributed to the conductive nature of polyaniline (PANI) and the dielectric loss associated with titanium dioxide (TiO2). In addition to EMI shielding performance, the mechanical and thermal properties of the PANI-PVA-TiO2 nanocomposite are of significant interest. The blend of polyvinyl alcohol (PVA), known for its excellent film-forming capabilities and flexibility, provides good mechanical stability to the composite, making it suitable for practical applications [6 -8]. Kanavi et al., [9] reported the in-situ polymerization of polyvinyl alcohol-polyaniline composite films with varying concentrations of zinc oxide (ZnO) (0.2%, 0.4%, 0.6%, and 1%), which were then cast and dried. Several methods were used to characterize the ZnO and PPZ film samples. It was discovered that the AC conductivity of PPZ1 was 20.06 S/m at 150 °C and 1% ZnO content. The PPZ films' usefulness is demonstrated by such conductivity behaviour samples. Moreover, the thermal stability of the composite tends to improve with the inclusion of ZnO, which aids in heat dissipation, an essential feature for materials used in electronics exposed to heat. Shakir et al., [10] reported the electromagnetic interference (EMI) shielding properties of PS/PANI blend films in the microwave and near-infrared (NIR) spectrums were examined. A shielding effectiveness of 45 dB was found in the frequency range of 9 GHz to 18 GHz. The NIR analysis of CPBs revealed a transmittance of less than 1%. In the presence of a homogeneous magnetic field of 0.5 T, Ge et al. created a hollow spherical nanostructure of PANI/CoS/CDs; the nanostructure under a 0.5 T magnetic field shown improved results [11]. The core-shell structural MnFe3O4@SiO2 nanocomposite was developed by Zhu et al. [12] and in order to create a ternary composite and analyze the microwave absorption, they combined them with polyaniline and polyvinylidene fluoride. They explained that the dielectric and magnetic loss are significantly impacted by the ternary compound of MnFe3O4@SiO2 with PANI and PVDF. Luo et al. [13] investigated the microwave absorption characteristics of polyaniline (PANI) and erbium (Er) doped strontium ferrites. A polyurethane (PU)-PANI composite sheet, measuring 1.9 mm in thickness, exhibits an average shielding effectiveness (SE) of approximately 10 dB in the X-band, achieving a maximum electromagnetic interference (EMI) SE of about 26.7 dB at 8.8 GHz. According to Saini et al. [14], the PANI-multiwall CNT dispersed polystyrene (30 weight percent) composite, with a thickness of 1 mm, exhibits an electromagnetic interference shielding effectiveness (EMI SE) of approximately 24 dB in the Ku-band (12.4–18 GHz). Furthermore, it was reported that an EMI SE of 40 to 45 dB could be attained in the same frequency band by increasing the thickness to 2 mm. Hong et al. [15] investigated the electromagnetic interference (EMI) shielding effectiveness (SE) of polyaniline emeraldine salt (PANI ES) films over a wide frequency range of 50 MHz to 13.5 GHz. They observed that the PANI ES film, with a thickness of 90 µm, exhibits an EMI SE of approximately 18 dB, which includes an EMI SE from absorption (SEA) of about 12 dB and an EMI SE from reflection (SER) of around 6 dB [16-18]. In the present study, we have reported the preparation of PANI – PVA – TiO2 nanocomposite by solvent casting method. The prepared nanocomposite employed for FTIR and SEM analysis.
MATERIALS AND METHOD
All the chemicals used for the preparation of PANI – PVA – TiO2 nanocomposite are analytical grade. The aniline monomer (C6H5NH2) with mol.wt 93.13 and 99.5 % purity, ammonium persulfate (APS) with 99.9 % purity, titanium nitrate (Ti(NO3)4) with 99 % purity, and 99 % purity isopropyl alcohol (C3H8O), sodium dodecylbenzene sulfonate (SDBS) with 99 % purity, and hydrochloric acid (HCl) were procured from Merck. All the obtained chemicals were used directly in experiments except aniline, which was first distilled, and then it was put in a cool and dark place before usage.
2.1 Synthesis of Titanium dioxide
Titanium dioxide nanoparticles were synthesized through aqueous sol–gel route in acidic medium. 14.64 g of titanium nitrate (Ti(NO3)4) were added to a mixture of solvents i.e. isopropyl alcohol and water in 1:4 ratio. 10 mL of glycerin were added and pH of the aqueous solution was maintained at 1 using nitric acid. The mixture was stirred constantly for two hours at 70 ?. The sol formed was also dried at 70 ? for 24 h. The gel thus obtained was ground and calcined for 2 hrs at 500 ? to obtain titanium dioxide which is further washed with distilled water followed by acetone several times until get colourless aliquant [19, 20].
2.2 Synthesis of Polyaniline (PANI)
Synthesis 0f PANI was carried out by in-situ chemical oxidation polymerization Technique. Aniline (0.1M) was mixed in 1M hydrochloric acid with 1M sodium dodecylbenzene sulfonate (SDBS) and stirred for 15 to 20 min to form aniline hydrochloride. To this solution, add 0.1M of ammonium persulphate, which acts as an oxidizer was slowly added drop-wise with continuous stirring at 0-50C for 4 hrs to get polymerized. The precipitate was filtered, washed with distilled water, acetone and finally dried in an oven at 600C for 24 hrs to achieve a constant mass. In this way, polyaniline (PANI) is synthesized [21].
2.3 Synthesis of Polyaniline – Polyvinyl alcohol (PVA) – TiO2 nanocomposite
Nanocomposite were prepared by doping 3 wt % of TiO2 in PANI via in-situ polymerization method [22]. The prepared nanocomposite blend was prepared by 0.3 wt % of polyvinyl alcohol (PVA) is mixed with PANI by mechanical grinding in acetone for 1 hr. 1.82 gm of PANI – PVA – TiO2 nanocomposite is dissolve in N-Methyl-2-pyrrolidone (NMP) stirred for 6 hrs and poured onto the glass plate to form a thin film [23].
3. Characterization
A Nicolet 750 spectrometer with a wavenumber range of 4000-400 cm-1 was utilized for Fourier Transform Infrared Spectroscopy (FTIR) measurements. For the examination of morphology, a scanning electron microscope (SEM) with specifications - JEOL JAPAN, model JSM-6610 LV, operated in high vacuum mode at 20 kV, with adjustable voltage (1-30 kV), magnification (× 5 to × 300,000), and resolution (3 nm) was utilised. The SEM images of the powder of the fabricated composites of PANI and PANI-PVA-TiO2 nanocomposite were captured at different resolutions. A two-port vector network analyzer (VNA) (Make- Agilent N5230C, 10 MHz – 40GHz PNA-L) was employed to study the dielectric properties and shielding effectiveness of the composites. Using the imaginary part of complex permittivity, the AC conductivity (σac = 2πfεo ε”) of composites was calculated.
RESULTS AND DISCUSSION
4.1 Fourier Transform Infrared Spectroscopy
Figure 1 (a – d) shows the FTIR spectra of TiO2, PVA, PANI and PANI – PVA – TiO2 nanocomposite. Figure 1 (a) curve indicates that the characteristics peaks at 409 cm-1 is corresponds to Ti – O bending out of the plane, 483 cm-1 Ti – O stretching vibration in symmetrical plane, 612 cm-1 for Ti – O – Ti stretching vibration, and 3364 cm-1 for bending of hydroxyl (- OH) group of moisture molecules [24]. Figure 1 (b) curve shows the characteristics peaks of PVA at 1093 cm-1 is due to the C – O stretching of vinyl group, 1419 cm-1 for C – H bending of ether, 2862 cm-1 for C – H stretching in symmetry and 3225 cm-1 for hydroxyl (- OH) group of moisture molecules. Figure 1 (c) curve the FTIR spectra of PANI, which indicates the characteristic peaks at 834 cm-1 for aromatic C –H vibration in-plan, 1061 cm-1 for C – N stretching of aromatic ring, 1150 cm-1 for B–(NH+) = Q structure stretching, 1301 cm-1 is due to the long chain of aromatic ring used to determine the delocalization of charge carriers, 1454 cm-1 is attributed to the -C=C benzenoid ring stretching vibration, 1581 cm-1 for N=Q=N quinoid ring stretching vibration, and 3820 cm-1 for hydroxyl ion H(–OH) of water molecules [25]. Figure 1 (d) curve shows the PANI – PVA – TiO2 nanocomposite which indicates the following peaks at 409 cm-1, 483 cm-1, 612 cm-1, 913 cm-1, 1093 cm-1, 1180 cm-1, 1301 cm-1, 1419 cm-1, 1496 cm-1, 1636 cm-1, 2862 cm-1 and 3395 cm-1. It is observed that the PVA and TiO2 peaks appeared in PANI nanocomposite which confirms the formation of PANI – PVA – TiO2 nanocomposite [26].
S. Manjunatha*, Fabrication P-N Heterostructure Of Polyaniline Polyvinyl Alcohol Tio2 Nanocomposite for Effective Electromagnetic Shielding Application, Int. J. Sci. R. Tech., 2025, 2 (4), 390-403. https://doi.org/10.5281/zenodo.15245566
10.5281/zenodo.15245566
