Structural Properties of Prepared PANI/TiO 2 Nanocomposite by Chemical Polymerization

A progression of Polyaniline (PANI) and Titanium dioxide (TiO 2 ) nanoparticles (NPs) were prepared by an in-situ polymerization strategy within the sight of TiO 2 NPs. The subsequent nanocomposites were analyzed using Fourier-transform infrared spectra (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray Analysis (EDX) taken for the prepared samples. PANI/TiO 2 nanocomposites were prepared by various compound materials (with H 2 SO 4 0.3 M and without it, to compare the outcome of it) by the compound oxidation technique using ammonium persulfate (APS) as oxidant within the sight of ultrafine grade powder of TiO 2 cooled in an ice bath. Nanocomposites were prepared by the addition of TiO 2 with two weight ratios (0.3 and 0.5 wt. %) during the polymerization of PANI. The outcomes showed good collaboration between PANI and TiO 2 . FTIR spectral shows a shift to higher wave numbers in the peaks of PANI/TiO 2 nanocomposites, due to the Coulomb force that resulted from the interaction between the TiO 2 nanoparticles with PANI. SEM results show that the TiO 2 nanoparticles enwrap the polyaniline and agglomeration of uneven distribution of TiO 2 particles can be seen in the PANI matrix. The intensity of the peak in the EDX analyses was found to appear by adding the nanoparticles. XRD pattern of PANI polymerization and PANITNCs shows that the TiO 2 NPs and PANI affected the crystallization performance of nanocomposites, it was identified that the TiO 2 NPs form a relatively irregular distribution in the PANI chain.


Polyaniline (PANI)
Polyaniline (PANI) is a renowned conductive polymer, and it got gigantic consideration from specialists in the areas of nanotechnology to improve sensors and optoelectronic devices. PANI is effectively doped with various acids because of its simple blend and amazing ecological stability [1]. Researchers have focused on creating conductive polymers that are accomplished in the fields of optics, devices, energy, etc. [2,3]. PANI was known first as dark aniline and then came in various structures relying upon its oxidation levels. Moreover, PANI is known for its simplicity [4], natural steadiness, and capacity to be doped by protonic acids [5]. PANI is associating 1, 4-coupling of aniline monomer parts. PANI could exist in various oxidation states, and it may be described with the FTIR benzenoid to the quinonoid proportions [6]. Formed conductive polymers mainly include polyaniline (PANI), polythiophene (PTH), polypyrrole (PPY), and their items [7].
Moreover, conductive polymers are used, for example, leading fillers in protecting polymer substrates to gain directing polymer compounds [10][11][12]. These mixtures have possible applications in electromagnetic interference shields, electronic equipment, and display device electrodes [13]. PANI is a kind of material showing reflecting detection at room temperature and useful activity, this way is an appealing possibility for the improvement of various gas sensors. PANI properties, including its detecting qualities, were viewed as changed by dopants or by connection point collaboration in the composite [14].

Titanium Dioxide (TiO 2 ) Nanoparticles
The titanium dioxide (TiO 2 ) nanoparticles are a typical oxide metal, n-type of semiconductor that displays fascinating photocatalytic and some electronic properties that were able to open many promising applications in photograph voltaic, photocatalysis, photograph electrochromic, and sensors. TiO 2 , particularly in the rutile structure, can oxidize natural materials straightforwardly because of its solid oxidative action. The presence of TiO 2 nanoparticles in the PANI lattice may cause a few changes and achieve some new fascinating properties [15]. Because of such presumptions, some research was done on the impact of the TiO 2 nanoparticles on gas detecting qualities of the PANI/TiO 2 blended by the in-situ method of synthetic polymerization [16].

Preparation
Aniline 99.0% (ANI), TiO 2 NPs rutile, and ammonium persulphate (APS, Kanto Chemical Co. Inc.) were used as starting materials for synthesizing the PANI/ TiO 2 nanocomposites. Every one of the materials was used as received. The system was completed with various compound materials (with H 2 SO 4 0.3 M and without it) as follows: a solution of 10 ml of ethanol and different proportion of TiO 2 (as displayed in Table 1) was on the stirrer for 30 min to make a solution of TiO 2 . The TiO 2 solution was then treated with a solution of 0.5 ml aniline (0.1M) and 0.3 M H 2 SO 4 (total solution 50ml). Then, a solution of 5 g ammonium persulphate with 50 ml distilled water was added dropwise to the ANI and TiO 2 solution blend. The two solutions were kept for 1 hr at 0 o C to polymerize. The solution was left to settle down until the following day. The precipitated PANI was gathered in filter papers. From that point onward, PANI powder was kept in a desiccator and left to dry in the air for about 3 days at room temperature to keep away from any impact of moisture absorption. The nanocomposite synthetic construction was investigated by FTIR, X-Ray diffraction analysis, Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray Analysis (EDX) taken for the prepared samples.

FTIR studies
The most important peaks observed in the FTIR spectra of raw materials shown in Fig. 1 and the FTIR spectra of the PANI/TiO 2 nanocomposites (PANITNCs) were it contains (PANI 0.1 M water-based only) and (PANI 0.1 M with H 2 SO 4 0.3M) are shown in Fig. 2. Pure aniline characteristic peaks (in Fig.1) were observed at 965 cm -1 C=C bending, 1141 cm -1 C=N imines bending, the stretching mode 1295 cm -1 C-N for benzenoid ring N=Q=N 1562 cm -1 C=C for the quinoid ring, 1491 cm -1 C=C benzenoid ring stretching N=B=N [17]. The bands at 760 cm -1 , 680 cm -1 , 560 cm -1 , 500 cm -1 and 468 cm -1 are related to (Ti-O-Ti) vibrations [18]. From the FTIR spectrum of TiO 2 nanoparticles in Fig. 1, it can be seen that the bands for Ti-O and Ti-O-Ti bonds are available in the 800 -400 cm -1 , the former being determined in a better wave number than the latter [19]. The 800 cm -1 peak is assigned to a (Ti-O) vibration, in which the oxygen atom is in a nonbinding situation.
The B-N H-B, which is shaped for the duration of protonation. The stretching frequency at 3431-3456 cm -1 is of the NH of the aromatic amine. Areas at 2852 to 2923 cm -1 are of CH vibration. The peaks in 1298-1301, and 1242-1245 cm -1 belong to the C-N stretching of the benzenoid ring. Peaks at 1242 cm -1 indicate the protonated form of polyaniline. The PANI bands at 1558, 1577, and 1481cm -1 belong to the C=N and the C=C modes of vibrations for quinonoid. and benzenoid. [20]. The results of FTIR demonstrated a shift of the peaks of PANI/TiO 2 nanocomposites to higher wave numbers due to the Coulomb force that resulted from the interaction between the TiO 2 nanoparticles and PANI, confirming that the structural and morphological changes in the nanocomposites have occurred. These assignments of vibrational modes of PANI and nanocomposites bands are listed in Table 2.   H, H1, H2, W, W1, and W2)   These peaks, in Fig.3, confirm the TiO 2 degree of crystalline, which is confirmed with JCPDS card numbers 21-1272 [21]. The XRD patterns are correlated with the same articles explaining and confirming the preparation of TiO 2 NPs. The peak value of 25.654°, which is one of the peaks for TiO 2 NPs, its correlated crystalline plane was (101). The crystalline size for the samples was observed from the Scherrer equation (Eq. (1) below) [22]:

X-Ray diffraction analysis
where: λ is the wavelength and D is the crystallite size, β-is the FWHM (full width out half maximum) of the XRD peak. The average crystalline size calculated for the prepared TiO 2 NPs was around 12 nm. The pure PANI peaks showed that a small peak is around 2θ = 18.495, 20.148, and 25.195, with a d spacing of 4.7933Å, 4.4037Å, and 3.5318Å indicating the conducting PANI; this also confirms the low crystalline structure. The crystalline size of the PANI is around 11 nm, which was calculated from the Scherrer equation [23].
For PANI/TiO 2 nanocomposites, the peak of the pure TiO 2 NPs phase indicates the amorphous nature of nanocomposites. PANI is polycrystalline in structure as shown in Fig.4, which may be allocated to the scattering of PANI chain at d spacing. Ammonium persulfate is mixed to the preparation technique; polymerization happens initially on the surface of TiO 2 NPs due to the restrictive impact of the surface. Thereafter, crystalline PANI combines the crystalline behaviors of TiO 2 NPs to obtain a polycrystalline structure. Therefore, the degree of crystalline of PANI decreases, and the X-ray diffraction peaks revealed combined and decreased with TiO 2 NPs peaks, and then, cannot be distinguished [24].
Comparing pure TiO 2 and pure PANI with nanocomposites, it is clear that the XRD of the PANI/TiO 2 nanocomposites is not identical to the crystalline structure of those of TiO 2 NPs. This explains that PANI polymerization of TiO 2 NPs has affected the crystallization performance of nanocomposites, it was identified that the TiO 2 NPs form a relatively irregular distribution in the PANI chain. Tables 3 & 4 listed the values of (2θ) of the strong peaks for the pure PANI and the nanocomposites. W1,  H1 (0.3%), and W2, H2(0.5%).

Scanning Electron Microscopy (SEM & EDX)
The morphologies of the pure PANI and 0.5 wt% TiO 2 (PANI/ TiO 2 ) nanocomposites were studied by SEM and EDX as shown in Fig.5. The SEM images show 2D nanosheet morphology. The nanocomposite sheets are rippled and crumpled, with dimensions ranging from 5 to 500 micrometers.  are noticed, and the strands are ordinary and uniform. Additionally, these strands will generally agglomerate into interconnected networks, which show numerous multiple different pores [25]. Fig.5-b shows the SEM images of the (PANI/TiO 2 ) nanocomposites. The change in surface morphology is observed with the addition of TiO 2 (0.5%) in PANI. An agglomeration of uneven distribution of TiO 2 particles can be seen in the PANI matrix. The diffraction pattern from particles of nanocomposite suggests that the TiO 2 nanoparticles are deposited on the surface of PANI and show a typical rutile phase. The EDX analyses of the polymer and nanocomposite are also performed to confirm the incorporation of the nanoparticles in the PANI matrix. The intensity of the NPs in the nanocomposites peaks is found to appear by adding the nanoparticles.

Conclusions
PANI/TiO 2 nanocomposite was synthesized with the aid of using in-situ chemical polymerization by various substance materials (with H 2 SO 4 0.3 M and without it), and the resulting PANI and PANI/TiO 2 nanocomposite base on the water is less efficient when contrasted with doping by H 2 SO 4 . An acidic medium promotes the solubilization of the monomer, the aniline, in water and limits the secondary reactions. The nature of the acid influences the polymerization time, morphology, physicochemical properties, and molar mass. It was displayed in the attributes of PANI/TiO 2 by XRD and FTIR that the nanoparticles will generally fix along the PANI chain with expanding TiO 2 concentration. The nanocomposite results were obtained with FTIR studies, which confirmed the formation of PANI/TiO 2 nanocomposites. It showed a shift to higher wave numbers in the peaks of PANI/TiO 2 nanocomposites. XRD pattern showed that the TiO 2 NPs and PANI significantly affected the crystallization performance of nanocomposites. SEM images show that the TiO 2 NPs enwrap the polyaniline and agglomeration uneven distribution of TiO 2 NPs can be seen in the PANI matrix. It was identified that the TiO 2 NPs form a relatively irregular distribution in the PANI confirming that structural and morphological changes in the nanocomposites occurred.