Sage Journals: Discover world-class research

Abstract

The etching of polymer surfaces has attracted considerable attention among polymer scientists and engineers owing to its wide range of applications in electronics and photovoltaic devices. In this work, the synergistic effects of HF etching and γ-irradiation at different doses (15, 25, and 35 kGy) on the structural and dielectric properties of PVA/SiO₂/Ag nanocomposites are systematically investigated. The chemical structure of the nanocomposites was analysed using Fourier transform infrared spectroscopy (FTIR). X-ray diffraction (XRD) results revealed an enhancement in the amorphous regions of the nanocomposites upon irradiation at 15 and 35 kGy. Scanning electron microscopy (SEM) images revealed a porous surface morphology, with pore size strongly dependent on the applied irradiation dose. The dielectric properties were found to be highly sensitive to γ-radiation exposure. Among all samples, the HF/PVA/SiO₂/Ag nanocomposite irradiated at 15 kGy exhibited the highest AC conductivity (σ_ac), dielectric constant, and dielectric loss. Quantitatively, this sample showed a maximum concluded DC conductivity (σ_dc) of 1.76 × 10⁻⁶ S·cm⁻¹, which is approximately one order of magnitude higher than that of the unirradiated composite (1.84 × 10⁻⁷ S·cm⁻¹). This enhancement is attributed to increased amorphous content and improved charge carrier mobility, facilitating more efficient hopping conduction pathways. In contrast, the sample irradiated at 25 kGy displayed a significant reduction in electrical performance, indicating that excessive irradiation may induce radiation-induced crosslinking. These findings demonstrate that γ-irradiation is an effective and controllable approach for tailoring the structural and dielectric properties of etched polymer nanocomposites, making them promising candidates for applications in energy storage, radio-frequency devices, and optoelectronics.

Keywords

Etching PVA silicon dioxide silver dielectric

Introduction

Nanocomposites present a promising avenue for a novel category of materials that synergistically combine the intrinsic characteristics of dispersed inorganic nanoparticles and host organic polymers. There has been a surge in the inclination towards nanocomposite materials that incorporate inorganic nanoparticles into polymer matrices in recent times.^1–5 Due to their inherent flexibility and low weight, polymers are ideal for producing nanocomposites, which can be readily processed and molded to meet specific size and shape requirements. Hence, the limitations of manipulating nanostructured matters can be surmounted by utilizing a polymer as a host matrix to incorporate nanoparticles.

Polyvinyl alcohol (PVA) is the world’s leading product of water-soluble synthetic resins. PVA resins’ physical, chemical, and biodegradable qualities make them useful. PVA is odorless and colorless. It forms films, emulsifies, and sticks. PVA’s strong tensile strength, flexibility, and barrier qualities make it a popular thin film material. PVA is used in textiles, surgical equipment, paper, food packaging, electronics, radiation shielding, coatings, building materials, and packaging. PVA makes thin, stable nanocomposite films.⁶ The backbone of its carbon chain is composed of methane carbons linked to hydroxyl (-OH) groups.⁷

Silicon is a widely exploited semiconductor owing to its advantageous properties, including a large bandgap, a broad optical transmission window, a wide absorption spectrum, controllable surface roughness, and effective anti-reflection capabilities. Consequently, silicon has been widely used in photonics,⁸ lithium‐ion batteries,⁹ solar cells¹⁰ and polymer composites.^3,4,11

Organic-inorganic hybrid networks, such as the PVA-SiO₂ system, demonstrate advantageous characteristics derived from both the inorganic and organic components, such as biocompatibility, thermal stability, chemical and corrosion resistance, rigidity, non-toxicity, elasticity, processability, flexibility, and high water permeability.¹² PVA/SiO₂ recently used in various applications like solar cell,¹³ sensors,¹⁴ and food packaging.¹⁵

The exceptional properties of silver nanoparticles (AgNPs) have been extensively explored across a wide range of applications, including antibacterial agents,¹² sensors,¹⁶ biosensors, photocatalysis,^17,18 and biomedical applications.¹⁹ Owing to their distinctive optical, electrical, magnetic, and catalytic characteristics, AgNPs are also highly effective as functional fillers for polymer matrices. In particular, their incorporation into polymers such as PVA significantly enhances mechanical strength, thermal stability, and barrier performance.²⁰

The targeted removal of material from polymeric surfaces, commonly called selective etching, has garnered significant attention from polymer scientists and engineers. This is primarily due to its potential applications in electronics and photovoltaics. The primary objectives of selective etching include enhancing surface roughness of polymeric materials, modifying surface chemical composition, eliminating or dissolving low molecular weight species that migrate to the surface, and alleviating residual surface stresses.²¹

Etching may change the shape of the material polymer surface and its chemical characteristics. Etching polymers before metal plating is a primary commercial use. Polymeric surfaces significantly impact metal plate adhesion and durability. Increased surface area increases metal deposition locations. Etching enhances chemical reactivity. Etching polymeric surfaces makes them hydrophilic, making surface treatments easier to apply.²² A novel and facile polymerization-induced assembly-etching strategy was proposed for the manufacture of wrinkled zeolitic imidazolate framework-67@polypyrrole (ZIF-67@PPy) microcages using ammonium persulfate-catalyzed pyrrole polymerization and concomitant acid etching for superior electromagnetic wave absorption (EMA) applications.²³ A one-step synthesis was employed to fabricate polyaniline (PANI)-coated vanadium dioxide (VO₂), in which VO₂ is in situ etched by protonic acid released during aniline polymerization, forming an interconnected nanofiber network. The PANI coating enhances electrical conductivity and strengthens multipolar polarization relaxation, endowing the VO₂@PANI composite with improved EMA performance.²⁴

Most polymeric surfaces are liquid-etched. Liquid etchants include organic solvents, oxidising acids, bases, and combinations of these. Liquid etchants roughen polymeric surfaces. Liquid etchant unsaturation and polar groups may affect a polymeric surface’s electrical state. A liquid etchant may generate a rough surface with many pits and holes by selectively dissolving a component in a heterogeneous mixture. Liquid etchants dissolve and change. Liquid etching removes surface low-molecular-weight fractions.²⁵ The surface modification of poly (lactic acid) (PLA) was achieved through an alkaline wet etching process to alter its properties for potential medical applications. The nano-roughness of treated 3D-printed PLA increased by 1.4 times compared to the control 3D-printed PLA.²⁶

In this work, porous PVA/SiO₂/Ag nanocomposites were successfully fabricated via an etching technique. The etching process was carried out by introducing HF into the PVA solution in the presence of silicon oxide and silver nitrate. The prepared nanocomposites were subsequently subjected to γ-irradiation at different doses to optimize their structural and dielectric properties. The enhanced dielectrical performance observed for the nanocomposites irradiated at 15 kGy indicates that this composition is particularly promising for polymer electrolyte and energy storage applications.

Experimental Techniques

Materials

Polyvinyl alcohol (PVA) (M.wt.: 1.15.000), HF (M.wt. 20.01, 40%), and silicon oxide (M.wt. 20.01:60.08) were gotten. From Loba Chemie, India. Silver nitrate (≥99.0%, M.wt. 169.87) was acquired from Merck specialties private Limited, India. Reagents were used as received.

Preparation of HF/PVA/SiO₂ Ag Nanocomposites

Nanocomposite films were prepared by solution casting. Briefly, HF (5.0 mL) was added to 83 mL of distilled water, followed by the gradual addition of PVA (10 g) under continuous stirring at 60°C until complete dissolution of the polymer. Subsequently, 1.0 g of SiO₂ was introduced, followed by the addition of AgNO₃ (1.0 g), and the mixture was stirred to ensure homogeneity. The resulting solution was transferred into plastic falcon tubes and irradiated with γ-radiation at absorbed doses of 15, 25, and 35 kGy, using a dose rate of 0.467 kGy h⁻¹. After irradiation, the solutions were poured into plastic Petri dishes and dried in an oven at 50°C for 24 hrs to obtain nanocomposite films. The γ-irradiation was performed using a ⁶⁰Co gamma-ray source at the National Centre for Radiation Research and Technology (NCRRT) of the Egyptian Atomic Energy Authority (EAEA). Scheme 1 represent the synthesis steps of HF/PVA/SiO₂/Ag nanocomposites.

Scheme 1.

Preparation of HF/PVA/SiO₂/Ag nanocomposites.

Characterization Techniques

The surface morphology of the polymer nanocomposite films was examined by scanning electron microscopy (SEM, ZEISS EVO 15, UK), and their elemental composition was analyzed using energy-dispersive X-ray spectroscopy (EDX). The chemical structure was investigated by Fourier transform infrared (FT-IR) spectroscopy in the range 400–3600 cm⁻¹. Structural characterization was performed using X-ray diffraction (XRD) with Cu Kα radiation (λ = 1.5405 Å) on a Shimadzu diffractometer operated at 40 kV and 30 mA over a 2θ range of 4°–90°. Dielectric properties and AC conductivity were measured at room temperature using circular disk samples (1 cm diameter, ∼0.1 mm thickness) coated with silver paste on both sides to ensure good electrical contact. Measurements were conducted over a frequency range of 0.1 Hz–10⁷ Hz using an impedance analyzer (IM-3570 RLC bridge, Japan).²⁷

Results and Discussion

FTIR

Infrared serves as a potent instrument for identifying functional groupings (such as vibrational bands like O-H, C-H, C = O) due to the analogous absorption frequencies of those groups across other molecules. Functional groups are structural entities in organic molecules characterized by specific atom and bond configurations. Figure 1 shows FTIR of pure PVA, unirradiated, and irradiated HF/PVA/SiO₂/Ag nanocomposites. The broadband at approximately 3288 cm⁻¹ is attributed to the stretching vibration of OH group in pure PVA, which is intramolecularly bonded. The band is observed to correspond to the asymmetric stretching vibration of CH₂ at approximately 2925 cm⁻¹.²⁸ The stretching mode of C=O has been assigned the peak at 1722 cm⁻¹. The absorption peak at 1430 cm⁻¹ has been attributed to symmetric bending of CH₂. The bands at approximately 1083 cm⁻¹ indicate the C-O elongation of carbonyl groups in the PVA backbone.²⁹ At 836 cm⁻¹, the C-C stretching vibrations of the moderate absorption planar zigzag carbon backbone are observed. The swaying mode of OH is responsible for the peak at 602 cm⁻¹. CH₂ rocking is shown by the peak at 927 cm⁻¹, whereas the peak represents (CH-OH) bending at 1322 cm⁻¹. The band observed at 1247 cm⁻¹ is linked to CH wagging.³⁰

Figure 1.

FTIR spectra of pure PVA film (a), unirradiated HF/PVA/SiO₂/Ag (b), irradiated with 15 kGy (c), 25 kGy (d), and 35 kGy (e).

From Figure 1(b), it is noticed that many changes occurred in the spectra of HF/PVA/SiO₂/Ag nanocomposites compared to pure PVA. For example, the intensities of all bands, such as OH, CH₂, and C-O, have increased. Also, the intensities of the peaks at 1430 cm⁻¹ and 1322 cm⁻¹ increased slightly. On the other hand, the intensity of the peak found at 602 cm⁻¹ decreased and was displaced to a higher wave number at 624 cm⁻¹. Moreover, the peak centered at 1246 cm⁻¹ has disappeared. In addition, new bands at 474 and 590 cm⁻¹ were observed, which were allocated to Si-O and C-F (halo compound) stretching.³¹

Moreover, the band at 1722 cm⁻¹ (C=O) has disappeared, and a new, weak band at 1663 cm⁻¹ indicates the formation of a C=C stretching vibration. All these changes indicate the interaction between PVA and the other components (HF, SiO₂, and silver).³² After irradiation, a new band at 728.6 cm⁻¹ was observed, attributed to C-F stretching and possibly combined with C=C bending. Also, by increasing the irradiation dose from 25 to 35 kGy, most of the band’s intensity found at 840 cm⁻¹ and 3288 cm⁻¹ decreased, which may indicate an increase in amorphisation of the material and the role of radiation in the etching process.^31,33

XRD

The XRD patterns of unirradiated and γ-irradiated HF/PVA/SiO₂/Ag nanocomposites are presented in Figure 2. All samples exhibit a dominant broad diffraction peak centred at 2θ ≈ 19.49°, which is indexed to the (110) crystallographic plane of PVA, confirming the semi-crystalline nature of the nanocomposite system.³⁴ Upon γ-irradiation at absorbed doses of 15 and 35 kGy, a noticeable broadening of the main diffraction peak is observed, as evidenced by an increase in the full width at half maximum (FWHM). This behavior indicates a reduction in crystallite size and an increase in the amorphous phase content.³⁵ The enhancement of amorphous regions can be attributed to radiation-induced free radical formation, hydrogen abstraction, bond cleavage, and the predominance of chain scission over crosslinking at these doses.^1,36 In contrast, irradiation at 25 kGy leads to a relative sharpening of the diffraction peak, indicating an increase in the crystalline phase. This behavior suggests that crosslinking becomes dominant over chain scission at this intermediate dose, thereby improving molecular ordering within the polymer matrix. The observed irradiation-induced structural evolution is expected to significantly influence the electrical behavior of the nanocomposites, with enhanced charge-transport pathways anticipated at optimal irradiation conditions, as discussed in the electrical measurements section.³⁷

Figure 2.

XRD for unirradiated HF/PVA/SiO₂/Ag and irradiated with 15 kGy, 25 kGy, and 35 kGy of γ-ray.

Surface Morphology

Scanning electron microscopy (SEM) is used to describe prepared nanocomposites’ structural morphology and porosity. Figure 3(a)–(d) displays the cross-sectional SEM images of HF/PVA/SiO₂/Ag nanocomposite films in their unirradiated condition and subsequent to γ-irradiation at various absorbed doses.

Figure 3.

Cross-sectional SEM image for unirradiated HF/PV/ASiO₂/Ag nanocomposites (a), irradiated with 15 kGy (b), 25 kGy (c), and 35 kGy (d) of gamma rays.

For the unirradiated sample, the polymer matrix exhibits a continuous, stiff, compact, and homogeneous structure with minimal porosity, indicating effective film formation via solution casting. The inorganic fillers are uniformly integrated within the PVA matrix without significant agglomeration, indicating effective filler dispersion. Following γ-irradiation at 15 kGy (Figure 3(b)), the surface of HF/PVA/SiO₂/Ag exhibits a marked increase in roughness, along with the emergence of microscopic pores and microvoids dispersed throughout the film. This morphological change is attributed to radiation-induced free radical formation and partial disruption of polymer chains, leading to localized matrix reorganization.¹ At an absorbed dose of 25 kGy (Figure 3(c)), the HF/PVA/SiO₂/Ag nanocomposite exhibits a highly porous and interconnected structure characterized by elongated voids and fibrillary elements. The increased porosity indicates significant restructuring of the polymer network induced by radiation. Increasing the irradiation dose to 35 kGy (Figure 3(d)) results in partial collapse of the porous structure and the formation of larger and irregular cavities. This behavior results from excessive radiation exposure, which induces predominant chain scission over crosslinking, thereby diminishing the film’s structural integrity and leading to a less uniform morphology.^38,39

Compositional analysis of synthesized nanocomposites before and after irradiation was performed using an energy-dispersive X-ray spectrometer (EDS).

The EDS analysis of HF/PVA/SiO₂/Ag nanocomposite films, presented in Figure 4, was performed for the unirradiated sample and those subjected to γ-irradiation at different absorbed doses. The EDS spectra of the unirradiated nanocomposite confirm the successful incorporation of all constituent elements. Pronounced peaks corresponding to carbon (C, 58.9 at.%) and oxygen (O, 39.5 at.%), originating from the PVA matrix, are observed, along with silicon (Si, 0.86 at.%) from SiO₂ and silver (Ag, 0.74 at.%). Minor variations in elemental composition are detected following γ-irradiation, which may influence the distribution and detectability of Ag and Si. These changes are attributed to radiation-induced crosslinking and structural rearrangements within the PVA matrix, consistent with previous reports.⁴⁰

Figure 4.

EDX for unirradiated HF/PV/ASiO₂/Ag nanocomposites (a), irradiated with 15 kGy (b), 25 kGy (c), and 35 kGy (d) of γ-rays.

Dielectric Analysis

The complex dielectric permittivity (ε*) characterizes a material’s ability to store electrical energy when subjected to an external electric field. In polymeric materials, dielectric polarization arises from several mechanisms, including dipolar orientation, ionic migration within the polymer matrix, and charge injection from the electrodes. The complex dielectric permittivity of the prepared blends was evaluated using equation (1), which is a key parameter for understanding their electrical behavior⁴¹:

ε^{*} = ε^{'} + j ε^{″}

(1)

where ε′ represents the dielectric constant and ε″ denotes the dielectric loss. These parameters were calculated using the following relations:

\begin{array}{l} ε^{'} = \frac{C d}{ε_{o} A}, & ε^{″} = \frac{σ}{{ω ε}_{o}} \end{array}

(2)

where d is the film thickness, A is the effective cross-sectional area of the electrode, C denotes the measured capacitance, ω is the angular frequency (ω = 2πf), and ε₀ is the permittivity of free space.

Figure 5 illustrates the frequency dependence of the dielectric constant (ε′) and dielectric loss (ε″) for pure PVA as well as unirradiated and γ-irradiated HF/PVA/SiO₂/Ag nanocomposites at room temperature. At low frequencies, the applied electric field varies slowly, allowing different polarization mechanisms—namely electronic, ionic, dipolar (orientational), and interfacial (Maxwell–Wagner–Sillars, MWS). As a result, high ε′ values are observed in this frequency regime. With increasing frequency, dipoles and mobile charge carriers can no longer follow the rapidly alternating field, leading to the gradual suppression of polarization processes and, consequently, a decrease in ε′.⁴²

Figure 5.

Dielectric constant (a) and Dielectric loss (b) dependency on frequency for pure PVA film (a), unirradiated and irradiated HF/PVA/SiO₂/Ag nanocomposites.

Pure PVA exhibits relatively low ε′ values across the entire frequency range due to its limited number of free charge carriers and the dominance of localized dipolar polarization associated with –OH groups along the polymer backbone.

In contrast, the ε′ value of the HF/PVA/SiO₂/Ag nanocomposites reaches approximately 4.65 × 10⁴ at 100 Hz, which is nearly five thousand times higher than that of pure PVA (ε′ ≈ 9.73) at the same frequency. This pronounced enhancement is attributed to strong interfacial (Maxwell–Wagner–Sillars) polarization arising from heterogeneous interfaces between conductive Ag species, insulating SiO₂ domains, and the polymer matrix.⁴³

Gamma irradiation significantly influences the dielectric response of the nanocomposites. At an absorbed dose of 15 kGy, both ε′ and ε″ increase relative to the unirradiated sample. This behavior is attributed to radiation-induced chain scission and bond rearrangements within the polymer matrix,⁴⁴ thereby increasing the amorphous content and enhancing dipolar flexibility. The higher amorphous phase facilitates dipolar orientation and ion–dipole interactions, thereby improving charge storage capability.

Consequently, irradiation at 15 kGy enhances the dielectric energy storage performance of the HF/PVA/SiO₂/Ag nanocomposites.

In contrast, increasing the irradiation dose to 25 kGy results in a reduction in ε′, associated with decreased amorphicity and the onset of dominant crosslinking effects. Crosslinking restricts the mobility of dipolar groups along the polymer chains, limiting their response to the alternating electric field and reducing polarization efficiency.

This dielectric behavior can be rationalized based on the combined effects of HF etching, Ag⁺ coordination, and γ-irradiation. In the presence of AgNO₃, Ag⁺ ions are homogeneously coordinated by the hydroxyl groups of PVA and partially interact with silica surfaces. HF selectively attacks amorphous SiO₂ through protonation of siloxane bonds followed by fluoride-induced dissolution, forming soluble hexafluorosilicate species:

{SiO}_{2} + 6 HF \to H_{2} {SiF}_{6} + 2 H_{2} O

(3)

Transient Ag⁺–F^- interactions locally enhance fluoride availability near silica domains, promoting controlled and localized etching. Partial removal of SiO₂ generates nanoscale voids, disrupts PVA–SiO₂ hydrogen bonding, and increases the polymer free volume. As a result, stable nanoporous structures are formed, while Ag⁺ species become confined near pore walls, contributing to the dielectric response.

Upon γ-irradiation, these confined Ag⁺ species are readily reduced to metallic Ag nanoparticles by radiation-induced electrons and polymer radicals. This spatial confinement promotes uniform distribution of Ag nanoparticles along the pore walls, enhancing interfacial polarization and significantly contributing to the observed dielectric enhancement. Overall, the synergistic effects of HF-induced silica dissolution, Ag⁺-mediated etching modulation, and γ-irradiation-induced structural rearrangements produce a porous nanocomposite with tunable dielectric properties. At 15 kGy, chain scission dominates, increasing amorphous content and charge carrier mobility, whereas at 25 kGy, enhanced crosslinking restricts dipolar motion and reduces dielectric performance.⁴⁵

A partial recovery of ε′ at 35 kGy can be attributed to competing effects between further structural rearrangements and localized degradation, although excessive irradiation generally limits long-range dipolar motion.

From Figure 5, the dielectric loss (ε″) decreases with increasing frequency for all specimens. The higher ε″ observed at lower frequencies can be attributed to mobile charges within the polymer matrix. At higher frequencies, the rapid oscillation of the applied electric field limits ion migration along the field direction, thereby reducing polarization contributions.⁴²

The elevated ε″ values of the nanocomposite irradiated at 15 kGy are further ascribed to the enhanced chain mobility of the polymer matrix. This increased mobility arises from a higher amorphous phase content, as confirmed by XRD analysis.³⁶

An important characteristic of polymeric nanocomposites is their AC conductivity (σ_ac), which underpins their applicability in electrical and electronic devices. The σ_ac of the nanocomposite was calculated using equation (4)⁴⁶

σ_{ac} = 2 π f ε^{'} ε_{ο} τ \tan δ

(4)

where tan δ represents the dissipation factor, f denotes the applied signal frequency, and ε_ο and ε′ represent the dielectric constants of free space and the material, respectively.

Figure 6 presents logarithmic plots of the σ_ac dependency on frequency for pure PVA, unirradiated, and irradiated nanocomposites. It has been shown that all samples’ σ_ac increase with frequency. This effect arises because an external electric field causes charge carriers to move more freely. In addition, releasing trapped charges is responsible for the change in alternating current conductivity.⁴⁷ The σ_ac dependency on frequency contains three different regions: low-frequency, intermediate, and high-frequency dispersion regions.

Figure 6.

AC conductivity dependency on frequency for pure PVA film (a), unirradiated and irradiated HF/PVA/SiO₂/Ag nanocomposites.

The high-frequency range corresponds to the collective relaxation of mobile ions due to Coulombic interactions between charge carriers. The intermediate region is attributed to ion mobility via a hopping mechanism, driven by long-distance diffusion. The low-frequency domain is ascribed to polarization of space charge at the interface of electrolyte-electrode, which is attributable to the electrode blocking.³⁶

Jonscher’s power law governs the behavior of AC conductivity, as follows:

σ_{ac} = σ_{dc} + A ω^{n}

(5)

The DC conductivity (σ_dc) of the nanocomposite is represented by the variables A and n, where A is the pre-exponential parameter and n is the power exponent, with 0 < n < 1. According to Arya et al. findings,⁴⁸ the values of n for an ideal Debye dielectric dipolar-type and ionic-type material are zero and one, respectively. Table 1 summarizes the parameter values. The augmented σ_dc of the HF/PVA/SiO₂/Ag nanocomposite compared to pure PVA is attributed to the increased mobility and concentration of charge carriers upon incorporation of fillers into the polymer matrix.³⁶ Also, it was observed that the nanocomposites irradiated with HF/PVA/SiO₂/Ag at 15 kGy have the highest σ_dc among the irradiated samples. This behavior is due to gamma-ray-induced chain scission at 15 kGy, which increases the amorphous phase, lowers the energy barrier, and enables easier ion transport.⁴⁹ In contrast, nanocomposites irradiated with 25 kGy have the lowest σ_dc among the nanocomposites due to a higher degree of crystallinity ascribed to radiation-induced crosslinking, which is consistent with XRD results.³⁷

Table 1.

Fitting parameters from Jonscher’s power law σdc, A and n for different samples.

Sample	σ_dc (S cm⁻¹)	A	Frequency exponent (n)
Pure PVA	6.6E-12	9.33E-13	0.922
HF/PVA/SiO₂/Ag unirrad.	1.84E-7	5.69E-9	0.511
HF/PVA/SiO₂/Ag 15 kGy	1.76E-6	2.957E-8	0.457
HF/PVA/SiO₂/Ag 25 kGy	1.4E-9	3.34E-11	0.54
HF/PVA/SiO₂/Ag 35 kGy	1.25E-8	2.01E-11	0.73

The dielectric modulus provides a more comprehensive understanding of charge transport processes, including relaxation mechanisms and ion dynamics, as they vary with frequency. The electric modulus (M^∗) may be computed by taking the reciprocal of the complex relative permittivity (ε^∗), as expressed in equation (6)⁵⁰:

M^{*} = 1 / ε^{*} = M^{'} + {iM}^{″}

(6)

where M′ and M″ refer to the real and imaginary components of M^∗ provided by⁵¹:

M^{'} = ε^{'} / (ε^{'} + ε^{″})

(7)

M^{″} = ε^{″} / (ε^{'} + ε^{″})

(8)

Figure 7 depicts the relationship between frequency and M′ and M″ for pure PVA and unirradiated and irradiated HF/PVA/SiO₂/Ag nanocomposites at room temperature.

Figure 7.

Real part of dielectrical constant (a) and imaginary part dielectrical constant (b) dependency on frequency for pure PVA film (a), unirradiated and irradiated HF/PVA/SiO₂/Ag nanocomposites.

It is evident that both M′ and M″ increase as the frequency rises, which indicates a contrasting behavior when compared to the patterns of ε′ and ε″.

Figure 7 also shows that M′ and M″ follow the typical pattern observed in various disordered materials. The observation of a lower M′ value for pure PVA at lower frequencies than ε′ indicates inhibition of electrode polarisation. It has been observed that Mʹ increases in frequency and attains a maximal saturation value at high frequencies, resulting from a short range of charge-carrier mobility.⁵² Due to the contemporaneous rise in the real component of permittivity, the observed pattern shows a reduction in Mʹ for HF/PVA/SiO₂/Ag nanocomposites.⁵³ The system irradiated with 15 kGy exhibits a lower M″ value than the unirradiated ones. Both have lower values than pure PVA, potentially attributable to increased charge-carrier mobility.⁵⁴ The M″ values exhibit a notable decrease at lower frequencies across all samples, suggesting the effective elimination of electrode polarisation. The observed increase in M″ with increasing frequency can be attributed to the distribution of relaxation across a range of frequencies.⁵⁴ Compared to other samples, the nanocomposite irradiated with 25 kGy has the highest M″, which is consistent with its lowest conductivity, as described earlier. The lack of a relaxation peak indicates an experimental frequency constraint, perhaps due to the increased ion density and the enhanced mobility of charge carriers in both irradiated and unirradiated systems.⁵⁴

Conclusion

Porous HF/PVA/SiO₂/Ag nanocomposites were effectively synthesized using the drop-casting method. Gamma irradiation induced significant, dose-dependent structural alterations in the nanocomposites. Irradiation at 15 and 35 kGy led to an elevated amorphous phase, attributed to the dominance of chain-scission mechanisms over crosslinking at these dosages. Irradiation at 25 kGy decreased amorphosity, indicating the prevalence of radiation-induced crosslinking and improved molecular organization. The dielectric response of the nanocomposites was strongly governed by the applied irradiation dose. The sample irradiated to 15 kGy exhibited the greatest enhancement in dielectric performance, with the highest σ_ac, dielectric constant, and dielectric loss among all investigated compositions. Also, this sample achieved the maximum σ_dc of 1.76 × 10⁻⁶ S·cm⁻¹, reflecting improved charge transport. This improvement is mainly linked to radiation-induced chain scission, which boosts charge-carrier mobility. In contrast, the prevalence of crosslinking at 25 kGy constrained dipolar motion, leading to diminished dielectric characteristics; hence, this sample displayed the greatest electric modulus values owing to its lowest conductivity. These findings indicate that γ-irradiation is a potent and manageable method for modifying the structural and dielectric characteristics of HF-etched polymer nanocomposites. The nanocomposite irradiated at 15 kGy is determined to be the best composition for energy-storage applications based on the integrated structural, dielectric, and modulus evaluations.

Footnotes

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

MM Atta

References

Atta

Taha

Abdelreheem

. Nitrogen plasma effect on the structural, thermal, and dynamic mechanical properties of PVA/starch/graphene oxide nanocomposite. Appl Phys A 2021; 127: 532. https://doi.org/10.1007/s00339-021-04671-x

Awad

Raslan

Abou‐Laila

, et al. Synthesis and characterization of waste polyethylene/Bi₂O₃ composites reinforced with CuO/ZnO nanoparticles as sustainable radiation shielding materials. Polym Eng Sci 2024; 64: 2747–2759. https://doi.org/10.1002/pen.26723

Gahramanli

Jafarov

Muradov

, et al. Structural, morphological, and optical properties of SiC/PVP nanocomposite materials by changing the SiC concentration in PVP. RSC Adv 2025; 15: 49990–50000. https://doi.org/10.1039/D5RA08712K

Gahramanli

Jafarov

Muradov

, et al. Correlation of SiC content with structural, optical, and dielectric characteristics in PVA-based nanocomposites: a comprehensive study. J Mater Sci 2025; 60: 17561–17579. https://doi.org/10.1007/s10853-025-11503-3

Shirinova

Surkhayli

Pashayev

, et al. Preparation, characterization and thermal properties of the PS+ Si based polymer nanocomposites. J Thermoplast Compos Mater 2025; 38: 1785–1798. https://doi.org/10.1177/08927057241288195

Atta

Abou‐Laila

Abdelwahed

, et al. Structural, mechanical, and thermal features of PVA/starch/graphene oxide nanocomposite enriched with WO3 as gamma–ray radiation shielding materials for medical applications. Polym Eng Sci 2023; 63: 3843–3854. https://doi.org/10.1002/pen.26490

Kalyani

Muthupandeeswari

. Investigation on the altered properties of PVA filled magnesium oxide composite (PVA@ xMgO) thin films. Polym Bull 2022; 79: 10115–10134. https://doi.org/10.1007/s00289-021-04004-1

Pavesi

DJL

. Lorenzo, silicon fundamentals for photonics applications, Springer2004. https://doi.org/10.1007/978-3-540-39913-1_1

Feng

Liu

, et al. Silicon‐based anodes for lithium‐ion batteries: from fundamentals to practical applications. Small 2018; 14: 1702737. https://doi.org/10.1002/smll.201702737

10.

Andreani

Bozzola

Kowalczewski

, et al. Silicon solar cells: toward the efficiency limits. Adv Phys X 2019; 4: 1548305. https://doi.org/10.1080/23746149.2018.1548305

11.

Jiang

Shi

Zhang

, et al. Recent advances in UV/thermal curing silicone polymers. Chem Eng J 2022; 435: 134843. https://doi.org/10.1016/j.cej.2022.134843

12.

Dippong

Toloman

Levei

E-A

, et al. A possible formation mechanism and photocatalytic properties of CoFe₂O₄/PVA-SiO₂ nanocomposites. Thermochim Acta 2018; 666: 103–115. https://doi.org/10.1016/j.tca.2018.05.021

13.

Alawi

Al-Bermany

. Newly fabricated ternary PAAm-PVA-PVP blend polymer doped by SiO₂: absorption and dielectric characteristics for solar cell applications and antibacterial activity. Silicon 2023; 15: 5773–5789. https://doi.org/10.1007/s12633-023-02477-5

14.

Hashim

. Fabrication and characteristics of flexible, lightweight, and low-cost pressure sensors based on PVA/SiO₂/SiC nanostructures. J Mater Sci Mater Electron 2021; 32: 2796–2804. https://doi.org/10.1007/s10854-020-05032-9

15.

Sabr

Hussein

Obaid

. Improving mechanical and morphological characteristics Pva/Sio2 nanocomposites for food packing applications. In: IOP Conference Series: Materials Science and Engineering. IOP Publishing, 2021, p. 012146. https://doi.org/10.1088/1757-899X/1094/1/012146

16.

Sahu

Kurrey

Khalkho

, et al. α-Cyclodextrin functionalized silver nanoparticles as colorimetric sensor for micro extraction and trace level detection of chlorpyrifos pesticide in fruits and vegetables. Colloids Surf A Physicochem Eng Asp 2022; 654: 129947. https://doi.org/10.1016/j.colsurfa.2022.129947

17.

Tene

Gahramanli

Muradov

, et al. Graphene/Ag–Ag₂S based hybrid nanostructure for methylene blue degradation. Front Chem 2025; 13: 1695385. https://doi.org/10.3389/fchem.2025.1695385

18.

Gahramanli

Muradov

Baghirov

, et al. Synthesis, characterization, and photocatalytic performance of 2D/1D graphene/Ag–Ag₂S hybrid nanocomposites. Dalton Trans 2025; 54: 15118–15133. https://doi.org/10.1039/D5DT01999K

19.

Chandraker

Lal

Dhruve

, et al. Bioengineered and biocompatible silver nanoparticles from Thalictrum foliolosum DC and their biomedical applications. Clean Technol Environ Policy 2022; 24: 2479–2494. https://doi.org/10.1007/s10098-022-02329-7

20.

Mostafa

Menazea

. Polyvinyl alcohol/silver nanoparticles film prepared via pulsed laser ablation: an eco-friendly nano-catalyst for 4-nitrophenol degradation. J Mol Struct 2020; 1212: 128125. https://doi.org/10.1016/j.molstruc.2020.128125

21.

Mijovic

Koutsky

. Etching of polymeric surfaces: a review. Polym-Plast Technol Eng 1977; 9: 139–179. https://doi.org/10.1080/03602557708055838

22.

Huang

Xie

Yang

, et al. Optical fiber fabry–perot humidity sensor based on porous Al₂O₃ film. IEEE Photon Technol Lett 2015; 27: 2127–2130. https://doi.org/10.1109/LPT.2015.2454271

23.

Ban

Liu

, et al. Polymerization-induced assembly-etching engineering to hollow co@ N-doped carbon microcages for superior electromagnetic wave absorption. Carbon 2023; 215: 118506. https://doi.org/10.1016/j.carbon.2023.118506

24.

Chu

Cheng

, et al. In situ etching by released proton in aniline polymerization to form network VO₂ doped polyaniline composites with variable infrared emissivity for electromagnetic absorption application. Adv Compos Hybrid Mater 2022; 5: 2760–2771. https://doi.org/10.1007/s42114-022-00566-4

25.

Eun

D-S

Bae

C-H

Kong

D-Y

, et al. Fabrication of microcylinder on silicon. Sensor Mater 2006; 18: 103–113.

26.

Kumara

SNBS

Senevirathne

Mathew

, et al. Nano-roughness modification of 3D printed poly (lactic acid) polymer via alkaline wet etching towards biomedical applications. 淡江理工學刊 2025; 28: 1331–1340. https://doi.org/10.6180/jase.202506_28(6).0015

27.

Atta

Zakaly

Almousa

, et al. Nitrogen plasma synthesis of flexible supercapacitors based on reduced graphene oxide/aloe vera/carbon nanotubes nanocomposite. Carbon Lett 2023; 33: 1639–1648. https://doi.org/10.1007/s42823-023-00548-6

28.

Eid

El-Arnaouty

Salah

, et al. Radiation synthesis and characterization of poly (vinyl alcohol)/poly (N-vinyl-2-pyrrolidone) based hydrogels containing silver nanoparticles. J Polym Res 2012; 19: 1–10. https://doi.org/10.1007/s10965-012-9835-3

29.

El-Arnaouty

Eid

Salah

, et al. Preparation and characterization of poly vinyl alcohol/poly vinyl pyrrolidone/clay based nanocomposite by gamma irradiation. J Macromol Sci, Part A 2012; 49: 1041–1051. https://doi.org/10.1080/10601325.2012.728466

30.

Eid

El-Arnaouty

Salah

, et al. Radiation synthesis and characterization of poly (aniline/glycidyl methacrylate)–Ag₂O nanocomposites. Inorg Chem Commun 2020; 114: 107844. https://doi.org/10.1016/j.inoche.2020.107844

31.

Johnson

Gao

Shields

IV , et al. Elastomeric microparticles for acoustic mediated bioseparations. J Nanobiotechnol 2013; 11: 1–8. https://doi.org/10.1186/1477-3155-11-22

32.

Kawady

Elkattan

Salah

, et al. Fabrication, characterization, and gamma ray shielding properties of PVA-based polymer nanocomposite. J Mater Sci 2022; 57: 11046–11061. https://doi.org/10.1007/s10853-022-07213-9

33.

Huseynov

Hakhiyeva

Mehdiyev

. FTIR study of nanocrystalline titanium carbide (TiC) particles exposed to gamma radiation. Solid State Commun 2024; 378: 115417. https://doi.org/10.1016/j.ssc.2023.115417

34.

Yassin

. Impedance, structural and thermal analyses of polyvinyl alcohol/polyvinyl pyrrolidone blend incorporated with Li+ ions for lithium-ion batteries. J Mater Res Technol 2021; 15: 754–767. https://doi.org/10.1016/j.jmrt.2021.08.063

35.

Hakhiyeva

Abiyev

Huseynov

. Comprehensive analysis of gamma irradiation-induced crystallographic transformations in TiC nanoparticles using X-ray diffraction techniques. Radiat Phys Chem 2025; 227: 112363. https://doi.org/10.1016/j.radphyschem.2024.112363

36.

Bhavsar

Patel

Singh

, et al. A comparative study on gamma and carbon ion irradiations induced modification in structural and electrical properties of PVA/H₃PO₄/SiO₂ nanocomposite polymer electrolyte. Radiat Phys Chem 2022; 192: 109916. https://doi.org/10.1016/j.radphyschem.2021.109916

37.

Aldosari

Atta

Henaish

, et al. Modulating structural, dielectrical and optical properties of PVA/methylcellulose/WO₃ nanocomposites for energy storage and optoelectronics applications. Polym Eng Sci 2025; 65: 215–227. https://doi.org/10.1002/pen.27003

38.

Bekhit

Fathy

Sharaf

, et al. Impact of gamma irradiation on physico-chemical and electromagnetic interference shielding properties of Cu₂O nanoparticles reinforced LDPE nanocomposite films. Sci Rep 2024; 14: 4144. https://doi.org/10.1038/s41598-024-54426-w

39.

Muradov

Baghirov

Eyvazova

, et al. Influence of gamma radiation on structure, morphology, and optical properties of GO and GO/PVA nanocomposite. Radiat Phys Chem 2023; 208: 110926. https://doi.org/10.1016/j.radphyschem.2023.110926

40.

Chahal

Mahendia

Tomar

, et al. γ-Irradiated PVA/Ag nanocomposite films: materials for optical applications. J Alloys Compd 2012; 538: 212–219. https://doi.org/10.1016/j.jallcom.2012.05.085

41.

Chen

Tang

Zhong

, et al. The dielectric constant and quality factor calculation of the microwave dielectric ceramic solid solutions. Ceram Int 2017; 43: 7383–7386. https://doi.org/10.1016/j.ceramint.2017.02.092

42.

El-Shamy

Attia

Abd El Kader

. Enhancement of the conductivity and dielectric properties of PVA/Ag nanocomposite films using γ irradiation. Mater Chem Phys 2017; 191: 225–229. https://doi.org/10.1016/j.matchemphys.2017.01.026

43.

Wan

Tao

Cao

, et al. Enhanced dielectric properties of homogeneous Ti₃C₂Tx MXene@ SiO₂/polyvinyl alcohol composite films. Ceram Int 2020; 46: 13862–13868. https://doi.org/10.1016/j.ceramint.2020.02.179

44.

Prabha

Jayanna

. Study the frequency dependence of dielectric properties of gamma irradiated PVA (1-x) PS x polymer blends. Open J Polym Chem 2015; 5: 47–54. https://doi.org/10.4236/ojpchem.2015.54006

45.

Mogoda

Ahmad

Badawy

. Characterization of stain etched p-type silicon in aqueous HF solutions containing HNO₃ or KMnO₄. Mater Chem Phys 2011; 126: 676–684. https://doi.org/10.1016/j.matchemphys.2010.12.063

46.

Elashmawi

Abdelrazek

Hezma

, et al. Modification and development of electrical and magnetic properties of PVA/PEO incorporated with MnCl₂. Phys B Condens Matter 2014; 434: 57–63. https://doi.org/10.1016/j.physb.2013.10.038

47.

Atta

Abdelhamied

Abdelreheem

, et al. Effects of polyaniline and silver nanoparticles on the structural characteristics and electrical properties of methylcellulose polymeric films. Inorg Chem Commun 2022; 135: 109085. https://doi.org/10.1016/j.inoche.2021.109085

48.

Arya

Sharma

. Structural, electrical properties and dielectric relaxations in Na+-ion-conducting solid polymer electrolyte. J Phys Condens Matter 2018; 30: 165402. https://doi.org/10.1088/1361-648X/aab466

49.

Abdelrazek

Abdelghany

Tarabiah

, et al. AC conductivity and dielectric characteristics of PVA/PVP nanocomposite filled with MWCNTs. J Mater Sci Mater Electron 2019; 30: 15521–15533. https://doi.org/10.1007/s10854-019-01929-2

50.

Ahmed

Ibrahiem

El-Bayoumi

, et al. Structural, mechanical, and dielectric properties of polyvinylchloride/graphene nano platelets composites. Int J Polym Anal Char 2021; 26: 68–83. https://doi.org/10.1080/1023666X.2020.1845493

51.

Abdullah

Aziz

Saeed

. Structural and electrical properties of polyvinyl alcohol (PVA): methyl cellulose (MC) based solid polymer blend electrolytes inserted with sodium iodide (NaI) salt. Arab J Chem 2021; 14: 103388. https://doi.org/10.1016/j.arabjc.2021.103388

52.

Kandhol

Wadhwa

Chand

, et al. Study of dielectric relaxation behavior of composites of poly (vinyl alchohol)(PVA) and reduced graphene oxide (RGO). Vacuum 2019; 160: 384–393. https://doi.org/10.1016/j.vacuum.2018.11.051

53.

Psarras

Manolakaki

Tsangaris

. Dielectric dispersion and ac conductivity in—Iron particles loaded—polymer composites. Compos Appl Sci Manuf 2003; 34: 1187–1198. https://doi.org/10.1016/j.compositesa.2003.08.002

54.

Hema

Tamilselvi

Pandaram

. Conductivity enhancement in SiO₂ doped PVA: PVDF nanocomposite polymer electrolyte by gamma ray irradiation. Nucl Instrum Methods Phys Res Sect B Beam Interact Mater Atoms 2017; 403: 13–20. https://doi.org/10.1016/j.nimb.2017.04.074

Gamma irradiation-induced modifications in structural and dielectric behavior of hydrofluoric acid-etched PVA/SiO 2 /Ag nanocomposites

Abstract

Keywords

Introduction

Experimental Techniques

Materials

Preparation of HF/PVA/SiO2 Ag Nanocomposites

Characterization Techniques

Results and Discussion

FTIR

XRD

Surface Morphology

Dielectric Analysis

Conclusion

Footnotes

Declaration of Conflicting Interests

Funding

ORCID iD

References

Preparation of HF/PVA/SiO₂ Ag Nanocomposites