# Fabrication and Investigating the Structural and Dielectric Characteristics of In₂O₃-GO/PMMA-PC Nanostructures for Electronics Nanodevices

<figure><img src="image_1.png" /></figure>

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Dhay Ali Sabur<fnref n="1" />, Majeed Ali Habeeb<fnref n="2" /> ID, Ahmed Hashim<fnref n="2" />* ID

Corresponding Author Email: pure.ahmed.hashim@uobabylon.edu.iq

https://doi.org/10.18280/rcma.330108

Received: 2 May 2022

Accepted: 1 February 2023

**Keywords:**

In₂O₃, nanocomposites, PMMA, dielectric properties, graphene oxide

## ABSTRACT

In this work, nanocomposites films of (PMMA-PC/In₂O₃-GO) were prepared using casting with various concentrations of (In₂O₃&GO) nanoparticles (0, 1.4%, 2.8%, 4.2%, and 5.6%). The structural and dielectric characteristics of the nanocomposite system (PMMA-PC/In₂O₃-GO) have been explored for usage in different optoelectronic applications. As a result, the topographical morphology of (PMMA-PC/In₂O₃-GO) nanocomposite films were studied using a scanning electron microscope (SEM). SEM images show many homogeneous and coherent aggregates or chunks on the upper surface. The dielectric characteristics of nanocomposites films were studied in the frequency range (100HZ-5MHZ). The dielectric constant, dielectric loss, and A.C electrical conductivity all rise with adding of (In₂O₃-GO) NPs. The dielectric constant and dielectric loss were reduced, while electrical conductivity was raised with rise in the frequency. Finally, the (PMMA-PC/In₂O₃-GO) nanocomposites may be useful in different electronics fields.

## 1. INTRODUCTION

Nanomaterials are a very important issue in the expanding use of polymers and nanomaterials with different physicochemical characteristics. One of their most distinguishing characteristics is their dielectric properties, which may be greatly altered by varying the shape, size, and conductivity of the combined elements in the polymeric matrix [1, 2]. Nanocomposites have based the concept of creating and fabricating innovative materials with exceptional flexibility and well physical characteristic using nanoscale building components. This definition can encompass porous medium, colloids, gels, and copolymers in the widest concept, although it is most commonly used to refer to the solid combination of a bulk matrix and nano-dimensional phase(s) with characteristics that differ owing to differences in structure and chemistry, the nanocomposites (mechanical, electrical, thermal, optical, catalytic) characteristics, and electrochemical will be extraordinarily different from those of the component materials [3]. Because of various benefits such as low weight, easy production processes, cheap cost, high fatigue strength, and strong corrosion resistance, many applications rely on the contribution of nanomaterial in polymers [4]. Polymethylmethacrylate (PMMA) is a transparent rigid thermoplastic polymer that is extensively employed as a shatter-proof replacement for glass. Due to its various technical advantages over other transparent polymers. It is often employed, in a sheet form, as light weight or shatter-resistant alternative to glass. PMMA is frequently utilized related to its moderate physical and mechanical characteristics, easy processing, and few cost [5]. Nanocomposites with PMMA matrix doped with different materials have various

applications such as electronics, optoelectronics and optics fields [6-9]. Polycarbonate (PC) as a thermoplastic polymeric matrix is considered of hardest polymers materials with the transparency highest level. Then, films of polycarbonate (PC)-based nanocomposites include not only flexibility but as well excellent tensile strength [10]. Grapheneoxide (GO) is an oxidation product of graphene, having several oxygen-containing groups, such as hydroxyl, carboxyl, epoxide, and carbonyl functional groups. The presence of these functional groups makes GO sheets strongly hydrophilic, allowing them to disperse easily into water with great stability [11]. This research aims to fabricate (PMMA-PC/In₂O₃-GO) nanocomposites and investigate the structural and dielectric characteristics to employ them in various dielectric and electronic applications.

## 2. MATERIALS AND METHOD

Polymethylmethacrylate (PMMA), polycarbonate (PC), indium oxide (In₂O₃NPs), and graphene oxide (GO) were employed in this study. The casting technique was used to prepare nanocomposites films (PMMA-PC/In₂O₃-GO). The films were prepared by dissolving 1g of the (PMMA-PC) blend with 80/20 percent in chloroform using a magnetic stirrer. The (In₂O₃-GO) NPs were introduced in the polymeric blend by (1.4, 2.8, 4.2 and 5.8) wt.%. The dielectric properties are determined in the frequency range 100Hz-5MHz using an LCR meter.

The dielectric constant (ε) is given by [12]:

$$ \epsilon = C_p/C_0 \quad (1) $$

<footnote n="1">¹Department of Optics Techniques, Al-Mustaqbal University College, Babylon, 51001, Iraq</footnote>

<footnote n="2">²Department of Physics, College of Education for Pure Sciences, University of Babylon, Babylon, 51002, Iraq</footnote>
$C_o$ and $C_p$ are vacuum and parallel capacitances. The dielectric loss ($ε''$) is determined by [13]:

$$ε'' = \dot{\epsilon} D \qquad (2)$$

D is the dispersion factor. The A.C conductivity was determined using [14]:

$$\sigma_{A.C} = W \epsilon'' \epsilon_0 \qquad (3)$$

W is the angular frequency.

### 3. RESULTS AND DISCUSSION

Figure 1 shows SEM images of (PMMA-PC/In₂O₃-GO) nanocomposites with various concentrations of (In₂O₃-GO)NPs. The surface morphology of the nanocomposites (PMMA-PC/In₂O₃-GO) films can be seen in this figure. SEM image of nanocomposite film at low (In₂O₃-GO) concentration, the image reveals a lot of randomly distributed aggregates or particles on the top surface, which are attributed to the presence of 1.4% of In₂O₃-GO, which are aggregated in clusters form. The results show that when the concentration of nanoparticles rises, the number and size of white dots on the surface increase (In₂O₃-GO). This may be attributed to the formation of larger clusters, which in turn expanded to form network paths of aggregates through the PMMA/PC blend. The surface morphology of the films shows a homogeneous density of grain boundaries. The results also show that nanoparticles prefer to form well-dispersed aggregates in (PMMA-PC) blend films, which might be a symptom of a homogenous growth process. As well as, this change belongs to the strong interfacial interaction of the functional groups on the surface of nanoparticles (In₂O₃-GO) with a blend polymer that displayed an important change in the nanocomposites morphology and mechanical reaction. Figure 2 and Figure 3 indicate the variation of the dielectric constant with frequency and contents of In₂O₃ and GO NPs respectively. The dielectric constant of the (PMMA-PC) blend was increased from 1.6 to 4.3 when In₂O₃-GO nanoparticles contents reached 5.6%. At higher frequencies, directional polarization decreases, resulting in a reduction in the dielectric constant with frequency. At low frequencies, the molecule can be fully oriented, but at middle frequencies, there is limited time for orientation [15]. At high frequencies, molecular orientation is impossible [16]. The shape of the compound, especially if it comprises air gaps and agglomerates, can also have a significant impact on the dielectric constant [17]. Figure 4 indicates the effect of (In₂O₃-GO) concentrations on dielectric loss for (PMMA-PC) blend at 100Hz. The dielectric loss diminishes as the frequency rises to 100 kHz or higher until it approaches a constant value. According to Koop's theory, a polycrystalline material consists of grains and grain boundaries, with the former being more resistant than the latter, when the material is exposed to an alternating electric field charge carriers tend to concentrate at the grain boundary contacts, forming dipoles. Accumulation of charge carriers results in Maxwell Wagner interfacial polarization of space charge polarization. Due to the increasingly resistive nature of the grain boundaries, more charges are restricted in the composite film at the interfaces when the frequency is low. Figure 5 shows the value of dielectric loss increases as the concentration of additives (In₂O₃-GO) NPs increases, this is

due to the rise in charge carriers generated by the additives concentration increase [18, 19].

<figure><img src="image_2.png" /><figcaption>**Figure 1.** SEM images for (PMMA-PC/In₂O₃-GO) Nanocomposites: (A) for pure (B) for 1.4 wt.% In₂O₃-GO NPs (C) for 2.8 wt.% In₂O₃-GO NPs (D) for 4.2wt.% In₂O₃-GO NPs (E) for 5.6 wt.% In₂O₃-GO NPs</figcaption></figure>

<figure><img src="image_3.png" /><figcaption>**Figure 2.** Effect of the content of (In₂O₃-GO) NPs on dielectric constant for (PMMA-PC) blend at 100Hz</figcaption></figure>

Figure 6 shows the variation of A.C electrical conductivity for (PMMA-PC) blend with contents of In₂O₃-GO NPs. As the content of In₂O₃-nanoparticles increases, the A.C electrical conductivity of nanocomposites rises. Because the composition of dopant nanoparticles causes a rise in the number of charge carriers, the resistance of nanocomposites steadily reduces and the A.C electrical conductivity increases [20-22]. Furthermore, the nanoparticles create a route network in nanocomposites [23], particularly at nanoparticle concentrations of (4.8% and 5.6%) for (PMMA-PC/In₂O₃-GO) nanocomposites. Figure 7 shows the A.C electrical conductivity of (PMMA-PC/In₂O₃-GO) nanocomposites changes with frequency, the A.C electrical conductivity of (PMMA-PC/In₂O₃-GO) nanocomposites rises as the
frequency of the electric field increases, the frequency works like a pumping force, in this case, the charge carriers are pushed between various conduction states [24]. At low frequencies, there was a decrease in the number of ionization processes for (In₂O₃-GO) NPs in the (PMMA-PC) mixture because there was a higher charge rise at the electrode-electrolyte interface. In the high-frequency region, charge carriers were more mobile, as a result, the electrical conductivity of (PMMA-PC/In₂O₃-GO) nanocomposites rises with frequency [25, 26]. The values of dielectric constant, dielectric loss, and A.C electrical conductivity for (PMMA/PC/In₂O₃/GO) nanocomposites at 100 Hz listed in Table 1.

<figure><img src="image_4.png" /><figcaption>**Figure 3.** Variation of dielectric constant of (PMMA-PC/In₂O₃-GO) nanocomposites with frequency</figcaption></figure>

<figure><img src="image_5.png" /><figcaption>**Figure 4.** Dielectric loss variation with frequency for (PMMA-PC/In₂O₃-GO) nanocomposites at room temperature</figcaption></figure>

<table><caption>**Table 1.** Values of dielectric constant, dielectric loss, and A.C electrical conductivity for (PMMA/PC/In₂O₃/GO) nanocomposites at 100 Hz</caption><thead><tr><th>Wt.% NPs</th><th>ε'</th><th>ε''</th><th>σ<sub>A.C</sub> (Ω.cm)<sup>-1</sup></th></tr></thead><tbody><tr><td>0</td><td>1.63</td><td>0.111</td><td>6.33×10<sup>-12</sup></td></tr><tr><td>1.4</td><td>1.9</td><td>0.191</td><td>1.06×10<sup>-11</sup></td></tr><tr><td>2.8</td><td>3.49</td><td>1.22</td><td>6.81×10<sup>-11</sup></td></tr><tr><td>4.2</td><td>3.69</td><td>2.22</td><td>1.23×10<sup>-10</sup></td></tr><tr><td>5.6</td><td>4.13</td><td>4.34</td><td>2.41×10<sup>-10</sup></td></tr></tbody></table>

<figure><img src="image_6.png" /><figcaption>**Figure 5.** Dielectric loss for (PMMA-PC) blend at 100Hz as a function of (In₂O₃-GO) NPs content</figcaption></figure>

<figure><img src="image_7.png" /><figcaption>**Figure 6.** Variation of A.C electrical conductivity for (PMMA-PC) blend with contents of In₂O₃-GO NPs</figcaption></figure>

<figure><img src="image_8.png" /><figcaption>**Figure 7.** The change of A.C electrical conductivity for (PMMA-PC/In₂O₃-GO) nanocomposites with frequency</figcaption></figure>
## 4. CONCLUSIONS

This work includes the synthesis of (PMMA-PC/In₂O₃-GO) nanocomposite and studying the structure, and dielectrical properties to use in different electrical applications. SEM shows that aggregates or chunks on the surface that are homogenous and coherent were studied using a scanning electron microscope SEM. The dielectric constant, dielectric loss and A.C electrical conductivity rise as the content of (In₂O₃-GO) increases. The dielectric constant and dielectric loss reduce as frequency rises, although the A.C electrical conductivity increases. When (In₂O₃-GO) NPs concentrations reached 5.6 percent, the dielectric constant of the (PMMA-PC) blend increased by a ratio of 60.61%, also the dielectric loss and A.C electrical conductivity increased by a ratio of 97.37%. The results indicate that the (PMMA-PC/In₂O₃-GO) nanocomposites could be used in a variety of optoelectronics applications.

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