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Article

Positional Isomeric Effects on the Physicochemical Properties of Polymeric Matrix and Polymer@TiO2 Nanocomposites

by
Badria M. Al-Shehri
1,
Amina Bekhoukh
2,
Soumia Benkhatou
2,
Imane Moulefera
3,
Afaf Y. Khormi
1,
Rabab A. Hakami
1,
Magbool Alelyani
4,
Jinan Abdelkader
5,
Abdelghani Benyoucef
2,* and
Youssef Bakkour
4,*
1
Department of Chemistry, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia
2
Water Science and Technology Laboratory, University of Mustapha Stambouli Mascara, Mascara 29000, Algeria
3
Chemical Engineering Department, Campus Universitario de Espinardo, University of Murcia, 30100 Murcia, Spain
4
Department of Radiological Sciences, College of Applied Medical Science, King Khalid University, Abha 61421, Saudi Arabia
5
Laboratory of Applied Chemistry, Faculty of Science III, Lebanese University, Tripoli 1352, Lebanon
*
Authors to whom correspondence should be addressed.
Appl. Sci. 2024, 14(5), 2106; https://doi.org/10.3390/app14052106
Submission received: 31 January 2024 / Revised: 22 February 2024 / Accepted: 27 February 2024 / Published: 3 March 2024
(This article belongs to the Section Chemical and Molecular Sciences)
Browse Figures
Versions Notes

Abstract

:
This study investigates the influence of positional isomerism on the physicochemical characteristics of polymeric matrices by examining polyo-anisidine (POA) and polyp-anisidine (PPA) in conjunction with TiO2 nanoparticles. The synthesis of POA@TiO2 and PPA@TiO2 involved chemical oxidative polymerization. X-ray diffraction analysis revealed the anatase structure of TiO2 nanoparticles. Transmission electron microscopy confirmed the successful integration of TiO2 nanoparticles within the polymer matrix. Moreover, FTIR and UV–Vis spectroscopy confirmed the effective interaction between the nanoparticle and the polymer. TGA indicated that POA@TiO2 exhibited a lower weight loss than PPA@TiO2, suggesting an enhancement in thermal stability. Although the incorporation of TiO2 nanoparticles led to a reduction in the electrical conductivity of the pristine polymers (PPA and POA), the resultant nanocomposites retained high conductivities within the range of 0.08 to 0.34 S.cm−1. Furthermore, the POA-based polymer matrix displayed promising electrochemical properties. Significantly, the adherence of the POA layer to TiO2 nanoparticles suggests potential practical applications.

1. Introduction

Conducting polymers (CPs) play an important role in material nanoscience and technology [1] due to their exceptional characteristics and versatile applications. These polymers are characterized by polyconjugated structures, which endow them with distinct electrical properties and stability, setting them apart from conventional polymers [1]. These polyconjugated structures have revolutionized the development of various electronic and electrochemical devices, leading to widespread applications in diverse areas [2], including metallic coatings, diodes, sensors, and microelectronic devices [2,3,4].
The continuous advancement of CPs and nanocomposites has brought attention to the impact of isomeric functional groups on their properties, highlighting the need for in-depth investigations in this area. Understanding how the positioning of functional groups within isomeric polymers affects their behavior and characteristics is crucial for optimizing their performance in various technological applications. They have an essential role in the domain of material science and technology [1]. Polyconjugated structures present in conducting polymers are widely used to determine electrical properties and their stability, which are unique to other conventional polymers [1].
Among the different types of conducting polymers, polyaniline (PAni) and polypyrrole, along with their derivatives, hold particular significance in both academic research and industrial applications [5]. These polymers exhibit a unique combination of electrical conductivity, mechanical flexibility, and chemical stability, making them highly desirable for a wide range of technological advancements. Researchers have extensively explored their properties and functionalities, paving the way for their integration into various cutting-edge technologies.
Given their ability to conduct electricity, these polymers have found use in the development of rechargeable batteries, contributing to the ongoing quest for more efficient and sustainable energy storage solutions. Moreover, their application to metallic coatings has facilitated the production of corrosion-resistant materials, enhancing the durability and longevity of various industrial components. Additionally, their role in the field of sensors has enabled the creation of highly sensitive and selective devices for detecting a wide range of substances and environmental changes. Furthermore, their integration into diodes, transistors, and microelectronic devices has revolutionized the landscape of modern electronics, enabling the development of smaller, faster, and more efficient electronic components. Continuous research and development in this field has not only expanded the fundamental understanding of conducting polymers but has also facilitated the development of novel materials with enhanced properties and functionalities. As a result, conducting polymers continue to be a key area of focus for scientists and engineers, driving innovation and progress in the realm of material nanoscience and technology.
Anisidine is a compound with a methoxy-aromatic amine group (methoxy aniline), considered a pollutant decomposition product of azo dyes. The methoxy (-OCH3) group position has been specified between the three isomers of ortho-, meta-, and para-anisidines [6]. It is inexpensive and has good solubility in water [7]. Additionally, poly(o-anisidine) is a polyaniline derivative with high stability and good mechanical properties. However, regarding human health hazards, it is classified as an inhalation toxicant due to its ability to form methemoglobin associated with humans and found in cats [6]. On the other hand, poly (P-anisidine) is a polyaniline isomer that increases a material’s specific capacitance and presents high stability as well as poly(o-anisidine) due to the methoxy group. Both polymers exhibit interesting characteristics such as high surface areas, electrochemical stability, and excellent redox [1].
Over the past decades, semiconductor photocatalysis has attracted considerable attention as an affordable and uncomplicated technology for wastewater treatment. Thus, extensive research has been conducted on nanostructured metal-oxide (MO) semiconductors such as TiO2 [8,9]. Despite being one of the more commonly employed photocatalytic materials [10], TiO2 has a relatively wide band gap ranging from 3.0 to 3.3 eV [8,11]. As a result, bare TiO2 only exhibits photoactivity under UV excitation, making it a disadvantage from this perspective. For this reason, researchers are exploring and developing TiO2-based photocatalyst systems with an improved visible-light response [10,11]. This effect has been obtained by coupling conducting polymers (PCs) with TiO2 photocatalysts, improving TiO2 photocatalytic efficiency [8,12]. However, conjugated polymers and their derivatives can act as photosensitizers and have shown excellent stability due to their extending π-conjugated electron systems. Therefore, the synergistic impact of combining these two types of materials (CPs and TiO2) to create a composite (CP@TiO2) may enhance one another and improve photocatalysis features including stability, quick reaction, and recovery [13]. On the other hand, pure TiO2 is typically considered an insulating material that is known for its high surface area. Hence, incorporating TiO2 into a CP matrix can lead to synergistic effects and increase the available surface area for electrolyte interactions, potentially improving charge storage and increasing electrical conductivity and electrochemical properties [14]. Understanding the interplay between phase structure and TiO2 addition is crucial for tailoring materials to meet specific requirements in photocatalyst and energy storage applications.
The main objectives of this work are to highlight the important role of a functional group’s position in isomers for polymer and nanocomposite properties, as well as to characterize the final composite obtained by doped isomers with TiO2 oxide such as FTIR, XRD, diffraction, TG analysis, and electrochemical properties.

2. Materials and Methods

2.1. Materials and Chemicals

The two isomers of anisidine (monomers), P-Anisidine (PA) and O-Anisidine (OA) (from Aldrich, Madrid, Spain.), were used as received. Chemicals such as perchloric acid (HClO4, 70% purity), hydrochloric acid (HCl, 37% purity), titanium (IV) oxide (TiO2, 99.98% purity), ammonium persulfate (APS, 98% purity), N-methyl-2-pyrrolidone (NMP), and ammonia solution (NH4OH, 25% purity) used in this work were of analytical purity and supplied by Merck KGaA (Darmstadt, Germany). The ultrapure water used in all the experiments was obtained from the Elga-Lab Water-Pure lab system.

2.2. Chemical Synthesis of Hybrid Materials

The two polymers (PPA and POA) and their corresponding nanocomposites with TiO2, PPA@TiO2, and POA@TiO2 were prepared via chemical oxidation [15,16,17]. Firstly, the desired TiO2 was dispersed in (1M) HCl under magnetic stirring for 30 min to activate the surface of TiO2 nanoparticles. Afterward, 0.25 mol of PA or OA monomers were prepared and preserved at room temperature in HCl. We added 0.5 g of a TiO2-activated mass to the previous solution, stirred it for 1 h to obstruct nanoparticle agglomeration, and allowed the electrostatic interaction to deposit monomers onto the TiO2 surface. Then, an APS (1M) was added dropwise at room temperature for 24 h. Afterward, the precipitates were placed in 50 mL of NH4OH (1M) at 25 °C while stirring for 2 h. Finally, the resultant mixtures were filtered, rinsed several times with H2O, and dried for 24 h at 65 °C [15,18,19].
Figure 1 depicts the polymerization process of PPA@TiO2 and POA@TiO2 nanocomposites [20]. In an acidic environment, the surface charge of TiO2 becomes positive, causing Cl– ions to adhere to the nanoparticle surface to balance the positive charges. Simultaneously, the monomers (PA or OA) undergo transformation into cationic anilinium ions under the same acidic conditions. This process causes electrostatic attraction between the Cl– ions attached to the surface and the cationic anilinium ions.

2.3. Physicochemical Characterization

The crystal structures of the prepared samples were studied using a Bruker CCD-Apex (Madison, WI, USA) model X-ray diffractometer (XRD). The specific micromorphology of the samples was observed by transmission electron microscopy (JEOL-JEM-2010; Peabody, MA, USA). A Hitachi U-3000 spectrophotometer was used to obtain UV–visible spectra. A Bruker–Alpha spectrophotometer (Varian, Inc., Palo Alto, CA, USA) was used to measure FT–IR and evaluate the functional units of the samples. A Hitachi STA–7200 instrument (Fukuoka, Japan) was used to perform thermogravimetric analysis (TGA) under nitrogen. About 10 mg of nanocomposites were heated to 900 °C with a heating rate of 20 K.min−1 [18,19].

2.4. Electrochemical Analyses

We studied the electrochemical behavior of the samples using cyclic voltammetry (CV). The material was initially dissolved in NMP. Subsequently, the dissolved polymers were extracted from the nanocomposites [15]. Afterward, a small volume of the resultant solution was deposited onto a glassy carbon electrode with a geometrical area of 0.07 cm2. The solution was dried using an infrared lamp to eliminate NMP. Electrochemical tests were conducted with a conventional 3–electrode cell setup. RHE (reversible hydrogen electrode) and platinum (Pt) were employed as reference and counter electrodes, respectively. A 1M solution of HClO4 was used as the electrolyte for all experiments, which were performed at a 50 mV.s−1 scan rate.

2.5. Electrical Conductivity Characterization

We used LucasLab resistivity equipment (Rochester, NY, USA) with 4-in-line probes to perform conductivity assessments. Before taking measurements, the materials underwent a drying process for 24 h. Pellets, each possessing a diameter of 0.013 cm, were fashioned using a mold of FTIR. These pellets were created by subjecting the materials to a pressure of 7.4 × 108 Pa.

3. Results and Discussion

3.1. FTIR Analysis

Figure 2a displays the FTIR spectra of TiO2 nanoparticles, POA, PPA, POA@TiO2, and PPA@TiO2. The locations of characteristic bands associated with the respective chemical bonds are summarized in Table 1.
The bands of TiO2 nanoparticles are associated as follows: the band at 3449 cm−1 is ascribed to stretching vibrations of the surface OH– or adsorbed H2O molecules; a band at 1634 cm−1 can be assigned to a vibration of –OH on the surface of TiO2, and the bands at 825 cm−1 and 661 cm−1 are due to Ti–O stretching modes [21].
The results in Table 1 demonstrate some differences between PPA and POA. The IR spectrum of pure POA exhibited a characteristic absorption band at 3185 cm−1 due to N–H stretching vibrations [22,23,24]. The bands at 2933 cm−1 are indicative of C–H stretching vibrations [25]. The two bands at 1591 cm−1 and 1499 cm−1 correspond to the quinoid and benzenoid groups, respectively [26,27]. The band at 1116 cm−1 is associated with C–O aromatics [12]. Moreover, a band appearing at 1418 cm−1 may be due to the presence of a CH3 group or aromatic characteristics [28]. The band observed at 1283 cm−1 can be attributed to the C–O–C vibrations of the ether group [12,29]. Additionally, the bands observed at 1146 cm−1 and 1338 cm−1 may be related to C–N and C=N stretching modes [22,30]. The band at 1018 cm−1 corresponds to the 1–4 substitution on the benzene ring [26,27] and the bands at 925 cm−1 and 809 cm−1 may be due to the C–H out–plane bending vibrations of 1,2,4 trisubstituted aromatic rings [23]. Therefore, these distinctive spectral features confirmed successful POA formation by FTIR spectroscopic analysis.
The findings presented in Table 1 highlight notable disparities between PPA and POA, notably in the position and intensity of their respective bands. IR spectra reveal that POA@TiO2 and PPA@TiO2 nanocomposites exhibit the principal characteristic bands found in pure polymers (POA and PPA). However, the discernible shift in all bands suggests an interaction between pure polymers and TiO2. Moreover, the presence of Ti–O bands between 716 cm−1 and 556 cm−1 in the FTIR spectra of nanocomposites serves as definitive evidence of the successful integration of TiO2 into the polymer matrix. This finding substantiates the notion of a chemical interaction occurring between TiO2 nanoparticles and the polymer structure, influencing spectral characteristics and affirming their amalgamation within composite materials [28,31].

3.2. XRD Analysis

The XRD patterns depicted in Figure 2b illustrate the XRD analyses of the POA polymer, PPA polymer, TiO2 nanoparticles, and PPA/TiO2, POA/TiO2 nanocomposites. The XRD pattern of PPA and POA conducting polymers exhibits a broad peak around 2θ (20°–30°). This specific value indicates an amorphous nature [30], possibly attributed to polymer chains scattering at interplanar spacings [23].
The XRD of both the POA@TiO2 and PPA@TiO2 nanocomposites was compared to those of the polymers (PPA and POA) and revealed distinct features. Notably, prominent peaks were observed at 2θ values of 25.28°, 36.9°, 37.81°, 38.57°, 48.05°, 53.85°, 55.03°, 62.12°, 62.69°, and 68.76° and were ascribed to the (101), (103), (004), (112), (200), (105), (211), (204), and (116) crystal planes of anatase TiO, respectively [28,32]. These findings decisively confirm the presence of TiO2 within both POA and PPA matrices. The XRD analysis also indicated that TiO2 retains its structural integrity even after dispersion within the polymer matrix following the polymerization process [28]. Additionally, a small, low-intensity peak around 32°, observed specifically in the hybrid material, likely corresponds to the presence of polymer@TiO2 materials via a chemical oxidation method [21], further supporting the successful integration and structural integrity of the hybrid materials.

3.3. Electrical Conductivity (EC)

The EC of polymers hinges significantly on the mobility and quantity of charge carriers, closely linked to the material’s morphology and chemical composition. Factors such as type, crystallinity degree, and tactile properties are pivotal in evaluating polymers’ electrical traits [33,34]. EC was determined for all products that underwent the previously described experimental conditions; the results are displayed in Table 2. As shown in Table 2 the polymer solids exhibited notably high conductivity at standard room temperature. Specifically, the POA sample displayed a conductivity of approximately 0.34 S·cm−1, whereas the PPA sample showed a lower conductivity of 0.22 S·cm−1. This discrepancy confirms that the PPA sample holds the least concentration of emeraldine salts, whereas the POA boasts the highest concentration. However, the introduction of nanocomposites resulted in a considerable decrease in conductivity levels. This reduction primarily stems from stereochemical variations among these nanocomposites.
The oxidized polymer displayed an almost linear structure, contributing to a minimal ionization potential because of the robust delocalization of electrons. This structural characteristic significantly impacts its conductivity. In this context, the decline in conductivity of nanocomposites suggests that the presence of TiO2 nanoparticles hampers or disrupts electron transportation pathways within the polymers. This interference likely occurs by potentially diminishing the length of polymer chains, which affects the material’s overall conductivity.

3.4. UV–Visible Analysis

Figure 3a presents the UV–visible spectra of POA, PPA, and PPA@TiO2, POA@TiO2 nanocomposites, where these materials were dissolved in an NMP solution. The three samples show two peaks: A peak near 298–378 nm, which can be attributed to transitions in the benzenoid structure [35,36], and a peak around 452–530 nm, which may correspond to quinine–imine group transitions [36,37]. These results reveal that polymer deprotonation by NH4OH forms emeraldine bases [38].
Intense band changes after inserting TiO2 nanoparticles and a notable redshift of the peaks were observed for pure polymers compared to nanocomposites. The redshift distribution of POA@TiO2 was larger than PPA@TiO2 likely due to interchain species, which profoundly impact the conjugated polymers’ process [28]. These results are in accord with nanocomposites’ decreased conductivity (various transitions are included in Table 3). The continuous variation in the UV–visible peaks’ wavelength and intensity confirms the interaction between polymers and nanoparticles.

3.5. TGA Analysis

In this work, TGA analysis was used to test the thermal stability of TiO2 nanoparticles, POA, PPA, POA@TiO2, and PPA@TiO2. The TGA profiles as a function of temperature in all synthesized materials are shown in Figure 3b.
The TGA curve of TiO2 presents minor weight loss below 450 °C, which can be associated with the elimination of H2O, ethanol, and partial dihydroxylation of TiO2 nanoparticles [12].
The TGA of all samples underwent four weight loss steps. An initial weight loss (5%) at temperatures over 120 °C was attributed to the evaporation of entrapped H2O, solvent, and monomers in the samples [39,40,41]. The second step of decomposition takes place at 160 °C to 450 °C and corresponds to the elimination of the oxidant. The third step of weight loss was observed in the range of 300 °C–500 °C and attributed to the removal of the acid dopant. Finally, the complete decomposition of polymer chains began near 500 °C and continued up to 630 °C for PPA and its nanocomposite PPA@TiO2 [41]. By contrast, it was 700 °C for POA, and even after 700 °C, total decomposition did not occur [42]. POA@TiO2 showed lower weight loss between 410 °C and 800 °C and the residue remaining in this zone provided an approximate estimate of filler content.
Moreover, at temperatures up to 600 °C, 62.5% of the PPA and 47% of the POA had decomposed. The POA@TiO2 nanocomposite presented greater thermal stability with a total mass loss of 25%. By contrast, PPA@TiO2 presented a higher mass loss of 32%. These results indicate that the interaction between the TiO2 particles and polymer chains may have limited the thermal motion of TiO2 particles and provided thermal stability to nanoparticles [43].
The weight mass loss of the three prepared polymeric samples displayed finite differences in their thermogravimetric analysis, indicating a minor decrease in the polymers’ weight mass loss compared to nanocomposites. Therefore, the nanocomposites’ thermal degradation presents higher stability than polymers. Additionally, the results show that the TGA curve of POA@TiO2 lost less weight than the PPA@TiO2 nanocomposite.

3.6. Electrochemical Study

CV was performed to test the polymers’ electroactivity. Figure 4 shows the CV curves of PPA, POA, POA@TiO2, and PPA@TiO2 materials obtained in HClO4 (1M) at 50 mV.s−1 scan rate. Regarding POA, three overlapping redox processes were observed. The first occurred at 0.45/0.20 V and resulted in a potential peak separation (Ep) of 250 mV. Another redox pair at 0.86/0.74 V presented an Ep close to 120 mV. This redox process was assigned to the leucoemeraldine/emeraldine and emeraldine/pernigraniline transitions, respectively [23,30].
The POA had similar CV shapes and peak potentials to the POA@TiO2 nanocomposite; however, the peak pairs were shifted to higher potentials and lower intensity. The CV profile of the PPA@TiO2 nanocomposite shows a unique redox process corresponding to 0.43/0.33 V and Ep = 100 mV, which corresponds to the leucoemeraldine/pernigraniline reaction [15]. Therefore, CV results may have been due to an earlier (lower) POA oxidation potential, i.e., higher POA reactivity than PPA [39]. Additionally, the anodic and cathodic peaks of PPA were symmetrical (EP/2C = EP/2a), indicating that the relevant redox events were highly reversible [40]. This reversible system corresponds to the p-doping of the polymer (oxidized) and n-doping of the polymer (reduced) represented by the oxidation wave and reduction wave, respectively. These findings show that the electrochemical properties of anisidine isomers depend on functional groups’ (-OCH3) relative position to one another, their arrangement in the polymer chain, and the existence of metal oxides in the polymer matrix.

3.7. TEM Analyses

Figure 5 displays TEM images of TiO2 nanoparticles and POA@TiO2 and PPA@TiO2 nanocomposites. TiO2 presents an almost spherical shape and uniform nanoparticle size with a diameter of about 100 nm, similar to those reported in the literature [44,45,46]. Moreover, all products had a spherical morphology, which was likely induced by absorbing monomers on the surface of TiO2 through H-bonding and electrostatic attraction after HCl acidified the TiO2 spheres. The TiO2 surface was modified during the acidification stage, and no other surface treatments were necessary [43]. Moreover, TEM images of the nanocomposites indicate that TiO2 particles were successfully dispersed into the polymer matrix [47].

4. Conclusions

In this study, two polymers incorporating the positional isomers para-anisidine (PPA) and ortho-anisidine (POA), along with their respective polymer@TiO2 nanocomposites, were prepared via in situ chemical oxidation with HCl as a dopant and APS as an oxidant. The physicochemical properties of all samples were influenced by positional isomeric differences. Significantly, POA demonstrated higher electrical conductivity and favorable electrochemical responses. Various analytical techniques, including XRD, TEM, FTIR, and UV–visible spectroscopy, confirmed the successful integration of TiO2 into the polymer matrix. This confirmation was evident through observed shifts in the peaks and bands within the spectra, indicating interactions between nanoparticles and the polymer. TGA revealed that the presence of nanocomposites improved the thermal stability of the polymers. Additionally, the electrochemical characteristics of POA@TiO2 outperformed those of PPA@TiO2.

Author Contributions

Conceptualization: B.M.A.-S., A.B. (Amina Bekhoukh), S.B. and I.M.; methodology: B.M.A.-S., A.B. (Amina Bekhoukh), S.B., I.M. and A.B. (Abdelghani Benyoucef); software: B.M.A.-S., A.B. (Amina Bekhoukh), S.B. and I.M.; validation: A.B. (Amina Bekhoukh), S.B., J.A. and A.B. (Abdelghani Benyoucef); visualization: A.B. (Amina Bekhoukh), S.B. and I.M.; formal analysis: A.B. (Amina Bekhoukh), A.Y.K., R.A.H., J.A. and A.B. (Abdelghani Benyoucef); investigation: A.B. (Amina Bekhoukh), J.A., M.A., Y.B. and A.B. (Abdelghani Benyoucef); data curation: B.M.A.-S., A.B. (Amina Bekhoukh) and Y.B.; writing—original draft preparation: B.M.A.-S., A.B. (Amina Bekhoukh), S.B., A.B. (Abdelghani Benyoucef) and Y.B.; supervision, A.B. (Abdelghani Benyoucef) writing, review and editing: B.M.A.-S., A.B. (Amina Bekhoukh), S.B., Y.B. and A.B. (Abdelghani Benyoucef). All authors have read and agreed to the published version of the manuscript.

Funding

This work was funded by the Deanship of Scientific Research at King Khalid University under grant number RGP2/358/44. The APC was also funded by King Khalid University.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Data are contained within the article.

Data Availability Statement

The datasets used in the current study are available from the corresponding author upon reasonable request.

Acknowledgments

The Deanship of Scientific Research at King Khalid University financially supported this work through Grant No. RGP2/358/44. Moreover, the authors also want to thank their parental universities for providing the facilities to accomplish this investigation.

Conflicts of Interest

The authors declare no conflict of interest.

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Applsci 14 02106 g001
Figure 1. Schematic representation of polymer@TiO2 nanocomposite preparation.
Figure 1. Schematic representation of polymer@TiO2 nanocomposite preparation.
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Figure 2. (a) FTIR analysis and (b) XRD powder diffraction patterns of TiO2 nanoparticles and PPA, POA, POA@TiO2, and PPA@TiO2 nanocomposites.
Figure 2. (a) FTIR analysis and (b) XRD powder diffraction patterns of TiO2 nanoparticles and PPA, POA, POA@TiO2, and PPA@TiO2 nanocomposites.
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Applsci 14 02106 g003
Figure 3. (a) UV–Vis spectra of samples; (b) TGA analysis of TiO2, POA, PPA, POA@TiO2 and PPA@TiO2 nanocomposites.
Figure 3. (a) UV–Vis spectra of samples; (b) TGA analysis of TiO2, POA, PPA, POA@TiO2 and PPA@TiO2 nanocomposites.
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Figure 4. CV recorded on glassy carbon electrode modified by synthesis samples in HClO4 (1 M) at a 50 mV.s−1 scan rate.
Figure 4. CV recorded on glassy carbon electrode modified by synthesis samples in HClO4 (1 M) at a 50 mV.s−1 scan rate.
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Figure 5. TEM images of (a) TiO2 nanoparticle; (b) PPA@TiO2, and (c) POA@TiO2 nanocomposites.
Figure 5. TEM images of (a) TiO2 nanoparticle; (b) PPA@TiO2, and (c) POA@TiO2 nanocomposites.
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Table 1. IR peaks of TiO2 nanoparticles and PPA, POA, POA@TiO2, and PPA@TiO2 nanocomposites.
Table 1. IR peaks of TiO2 nanoparticles and PPA, POA, POA@TiO2, and PPA@TiO2 nanocomposites.
Peak AssignmentPOAPPAPOA@TiO2PPA@TiO2TiO2
–NH Stretching vibrations3185319832713246//
–CH Stretching vibrations2933299828462840//
Quinonoid1591157215811566//
Benzenoid1499150415081501//
–C–N1338137513931305//
B–N+H–B & Q=N+H–B1018104010241024//
C–O aromatic1116115411231166//
CH3 group1418145014491443//
C–O–C1283129512461248//
TiO////716–556729–571825–544
Table 2. The EC values of POA, PPA, and PPA@TiO2, POA@TiO2 nanocomposites.
Table 2. The EC values of POA, PPA, and PPA@TiO2, POA@TiO2 nanocomposites.
SamplesPPA@TiO2POA@TiO2PPAPOA
EC (S.cm−1)0.080.090.220.34
Table 3. Absorption bands and redox peaks of prepared materials.
Table 3. Absorption bands and redox peaks of prepared materials.
MaterialsRedox Peak (V)Absorption Band (nm)
Epa1Epc1 Epa2Epc2
PPA0.400.360.040.740.710.03328503
POA0.410.300.110.670.510.16298530
POA@TiO20.450.280.170.670.560.11314512
PPA@TiO20.430.330.10///318452
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Al-Shehri, B.M.; Bekhoukh, A.; Benkhatou, S.; Moulefera, I.; Khormi, A.Y.; Hakami, R.A.; Alelyani, M.; Abdelkader, J.; Benyoucef, A.; Bakkour, Y. Positional Isomeric Effects on the Physicochemical Properties of Polymeric Matrix and Polymer@TiO2 Nanocomposites. Appl. Sci. 2024, 14, 2106. https://doi.org/10.3390/app14052106

AMA Style

Al-Shehri BM, Bekhoukh A, Benkhatou S, Moulefera I, Khormi AY, Hakami RA, Alelyani M, Abdelkader J, Benyoucef A, Bakkour Y. Positional Isomeric Effects on the Physicochemical Properties of Polymeric Matrix and Polymer@TiO2 Nanocomposites. Applied Sciences. 2024; 14(5):2106. https://doi.org/10.3390/app14052106

Chicago/Turabian Style

Al-Shehri, Badria M., Amina Bekhoukh, Soumia Benkhatou, Imane Moulefera, Afaf Y. Khormi, Rabab A. Hakami, Magbool Alelyani, Jinan Abdelkader, Abdelghani Benyoucef, and Youssef Bakkour. 2024. "Positional Isomeric Effects on the Physicochemical Properties of Polymeric Matrix and Polymer@TiO2 Nanocomposites" Applied Sciences 14, no. 5: 2106. https://doi.org/10.3390/app14052106

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