Chapter-4 CHARACTERIZATION OF POLYANILINE COMPOSITES 4

Chapter-4

CHARACTERIZATION OF POLYANILINE COMPOSITES

4.1 Introduction
It is said that a typical phenylene based polymer having a chemically flexible – NH – group in a polymer chain flanked either side by a phynelene ring is called PANI. Due to the presence of the -NH- group the protonation and deprotonation, and various other physico-chemical properties of PANI and its composites with V2O5, ZrO2 and PbS can be said to be there. Under acidic condition polyaniline and its composites with V2O5, ZrO2 and PbS are the oxidative polymeric products of aniline. Samples of PANI salt and its composites are characterized by Infrared and UV-visible spectroscopy, and by X-ray powder diffraction methods.
All types of electromagnetic radiations travel with the same speed, the velocity of light, but they differ in wavelength or frequency from each other. The increasing order of energies of the electromagnetic radiation is: Radiowaves < Microwaves < Infrared < Visible < Ultraviolet < X-rays < ?- rays n – ?* > ? – ?* > n- ?*, shown in figure 4.20.218-220

E
N
E
R
G
Y
?* Anti-bonding
?* Anti-bonding
n Lone-pair,
Non-bonding
? Bonding
? Bonding

Fig. 4.20

? – ?* is a transition of a electron from a bonding sigma orbital to the higher energy antibonding sigma orbital. This type of transitions not belongs to UV-visible spectra, as it requires high energy in the range of far uv (190-100 nm). n – ?* transition involves the transition of unshared pair electrons to the higher energy antibonding sigma orbital. These transitions require comparatively less energy than ? – ?* transitions. These are sensitive to hydrogen bonding, and occur due to the presence of non-bonding electrons on the hetero atoms and thus require greater energy. ? – ?* (K-band) transition is available in compounds with saturated centres, e.g., simple alkenes, aromatics, carbonyl compounds, etc. It requires lesser energy than n – ?* transition. In , ? – ?* transition, ? – bonding electron transfer to anti-bonding ?* orbital. In, n- ?* transition (R-band), an electron of unshared electron pair on a hetero atom is excited to anti-bonding ?* orbital. It requires least amount of energy than all other transitions and therefore, this transition gives rise to an absorption band at longer wavelengths. This transition is forbidden by symmetry consideration, thus the intensity of the band due to this transition is low, although the wavelength is long.
The band due to ? – ?* transition in a compound with conjugated ? system is usually intense and is frequently referred to as the K-band (German, Konjugierte) 347. The n- ?* transition is referred as R-band (German, Radikal). In conjugated system the energy separation between the ground and excited states is reduced and the system then absorbs radiation of longer wavelengths and with a increased intensity (i.e. K-band is intense and at longer wavelength). Moreover, due to lessening of the energy gap, the n- ?* transition due to presence of the hetero atom, the R-band also undergoes a red shift with little change in intensity. The B-bands i.e., benzonoid bands are characteristics of aromatic and heteroaromatic compoundsd. In benzene the B-band is at 256 nm which displays a fine structure with multiple peaks. Significantly the K-band (at 184 nm and 203.5 nm) and B-band (256 nm) of benzenes have low intensities.
The UV-visible spectrum of a compound is a plot of absorbance of the compound as a function of wavelength of radiation. All molecules in general and organic molecules in particular can absorb radiation in the UV-visible region because they contain electrons, which can be excited to higher energy levels. These electrons in molecules can be classified as sigma (?), pi (?), and nonbonding (n) electrons. The ? electrons are those, which are associated with single covalent bonds. Since they are tightly bound, radiation of high energy is required for their excitation. The electrons associated with multiple bonds are known as ? electrons. The ? electrons are rather easily excited to higher level.
It is well known that the absorption of electromagnetic radiation in the U-V-region of the spectrum provides important information about the energy bands assigning the electronic transitions. Optical absorption in conducting polymer and its composites, which are mostly amorphous or polycrystalline, may be due to the transition of charge carriers through a forbidden energy band, called optical band gap. On doping, it introduces additional energy band on the forbidden region, but it does not interfere with the principal energy band of the original polymer

4.3.2 Experimental Technique
A variety of instruments are available commercially for absorbance measurements in the UV- visible region, the photo calorimeter and the spectrophotometer meter. Photo calorimeter, however can be used to study the absorption of visible light only while spectrophotometers can be generally used, for studying both the UV and visible regions. The UV-visible spectra of the homopolymer, three inorganic additives (V2O5, ZrO2, and PbS) and their 14 composites with PANI under investigation were recorded in the dimethyl formamide (DMF) solvent at room temperature by using SL.171 Elico mini spectrophotometer, at department of pharmacy, R. T. M. Nagpur University, Nagpur.
4.3.3 Result and Discussion
U-V visible spectroscopy is a powerful tool for the study of protonation effect (and hence the formation of different oxidation states of the polymer) as well as for the elucidation of the interaction between the solvent, the dopant and the polymer chains. Figures 4.21 – 4.38 shows UV-Visible spectra for pure PANI and its composites. Each of spectra reveals the presence of two absorption bands, one in the visible region & the other in the UV region. The band in the UV region corresponds to the ?-?* transition and the band in the visible region corresponding to the inter ring charge transfer associated with excitation from benzonoid to quinoid moieties223,224. The ?max , their absorbance and band energies in UV-visible spectra for PANI, inorganic species V2O5, ZrO2, and PbS and their composites are shown in table 4.5.
For pure PANI salt (converted in to base in DMF84), the phenyl capped octa aniline shows two considerable absorption peaks in DMF179 viz., at 324 nm and 613 nm assigning the ? – ?* transition band (interband transition, transition in the benzenoid rings) and n- ?* exciton band (exciton transition from HOMO of benzenoid to LUMO of quinoid ring, or exciton absorption in quinoid rings)140,187,225 with absorbance 0.1464 and 0.0956 respectively, with their respective band gaps 3.826 and 2.022 eV, shows good agreement for conjugated polymer chain in PANI synthesized in aqueous medium. This investigated data is well agreed with the literature reported data. The excitation (n- ?*) leads to formation of molecular exciton, i.e., positive charge on the benzenoid units and negative charge centred on quinoid unit138. This interchain charge transfer may lead to the formation of positive and negative polarons. Both ? – ?* transition band and n – ?* exciton band are abundant in UV-visible spectra of most of the composites.

Table 4.5
Samples ?max (nm) Absorbance Band energy (eV)
? – ?*
Transition
Band n- ?*
Exciton
Band ? – ?*
Transition
Band n- ?*
Exciton
Band ? – ?*
Transition
Band n- ?*
Exciton
Band
PANI 324 613 0.1464 0.0956 3.826 2.0226
V2O5 331 760 0.0336 0.0482 3.745 1.631
ZrO2 265 —– 0.2203 —– 4.678 —–
PbS 333.5 > 800 0.0822 0.13 3.717 > 1.549
Composites
a 316 590 0.0996 0.0457 3.923 2.101
b 367 567 0.3201 0.1201 3.378 2.186
c 372 558 0.2336 0.08 3.333 2.222
d 379 543 0.219 0.1133 3.271 2.283
e 381.5 —– 0.6267 —– 3.25 —–
f 327 615 0.045 0.035 3.791 2.016
g 355.5 —– 0.0115 —– 3.487 —–
h —– —– —– —– —– —–
i 326 621 0.035 0.019 3.803 1.996
j 350.5 628 0.0084 0.009 3.537 1.974
k 327 607 0.3152 0.185 3.791 2.042
l 320 605 0.2154 0.096 3.874 2.049
m 322 595 0.210 0.075 3.850 2.083
n 315.5 604 0.0831 0.055 3.929 2.052

In case of samples a – e of PANI/V2O5 (organic-inorganic) composites, bathochromic shift or red shift (band energy decreases) of ? – ?* band and hypsochromic shift or blue shift (band energy increases) of n – ?* band is observed with increment in weight percent of V2O5 xerogel in composites. Also the absorbance at both bands increases (hyperchromic shift), become considerably high for up to 16% weight of V2O5, indicates the increased charge transfer from benzenoid to quinoid moieties, and decreases (hypochromic shift) for further increment in weight % of V2O5 in PANI/V2O5 organo-inorganic hybrids. High electrical conductivity of this composite has found for 16% weight of V2O5. For the higher weight % (40%) of V2O5 in sample, the peak at n – ?* obscured, corresponds to lowest electrical conductivity, it may because of over oxidation of PANI. These spectral changes indicate the coordination of V2O5 with nitrogen atoms226, and the blue shift of the band in visible region indicates the formation of composites between PANI and V2O5.
Not very regular shifts are observed in samples f – j of PANI/ ZrO2 (organic-inorganic), but with much weak absorbance, for all. Bathocromic shift with increasing weight % of ZrO2 at ? – ?* band is observed for samples f to g, and for i to j (8% to 16%, 32% to 40% wt % of ZrO2). For the samples g and h peaks at n – ?* band obscured, and both peaks at ? – ?* and n – ?* are absent for the sample h. This may because of vanished bonds associates ? – ?* and n – ?* bands in PANI by some undesired structural changes involved by interaction or coupling of ZrO2 with PANI structure. As compared to pure PANI salt, its composites with ZrO2 show strong hypochromic shift from PANI to composites.
All the samples from k to n of PANI/PbS composites shows very regular but slight hypsochromic shift (blue shift) and much large hypochromic shift at about both, transition and exciton bands, with increasing weight % PbS in composites. It indicates the formation of composites between PANI and PbS. But from PANI to PANI/8%PbS show very strong absorbance, more than double, for both bands, indicates the high charge transfer within benzene rings and from benzenoid to quinoid rings and it may desire to think about high conductivity for 8% weight of PbS in composites.
Most of the composites of PANI with inorganic additives, in their UV-visible spectra shows bathochromic (for a to e) shift, hypsochromic shift (k to n), hypochromic shift (for all, except a to b, and d to e), and hyperchromic shift (for a to b, and for d to e), with increasing weight % of inorganic species in composite samples. It quite sufficient to conclude that, the additives chemically interact/coupled with structure of PAN salt.
Spectra of PANI/PbS series show hypsochromic shift in both bands, indicates an increase in band gap brought about through an increase in the torsion angle between the C-N-C plane and the plane of benzene ring thus decreasing the conjugation. Inversely, spectra of a – e series of PANI/V2O5 and f to j series of PANI/ ZrO2 shows bathochromic shift for ? – ?*, indicates the decrease in band gap brought about through decrease in the torsion angle between the C-N-C plane and the plane of benzene ring, thus increasing the conjugation with increasing wt % of V2O5 in samples37,193,227. For all composites, their intrachain absorption lies in the range of band energy 3.929 – 3.25 eV, and interchain absorption in the range 2.283 to 1.974 ev 47.
When UV-Visible spectra of composites compared with the spectra of PANI, the introduction of the impurities in the aromatic ring of aniline produces a blue shift and also red shift for some samples. Ginder227 reported through the theoretical consideration that an increase in the dihedral angle or the ring torsion angle between adjacent aromatic ring of the polymer cause a blue shift. A twist in the torsion angle is expected to increase the average band gap in the ensemble of the polymer composites. Thus the result indicates that a polaron band is created in the band gap of polyaniline oxidation, and increase in the torsion angle (the angle by which the ring is twisted out of the plane of C-N band) will affect the bandwidth as well as average band energies37.
In general the UV- Visible spectra of the synthesized polymer (PANI), its composites with V2O5, ZrO2, and PbS are similar in nature and there is shift in ?max values for most of composite samples due to their structural changes arises by added impurities.

Fig. 4.21 UV-VISIBLE SPECTRA OF PANI

Fig. 4.22 UV-VISIBLE SPECTRA OF V2O5

Fig. 4.23 UV-VISIBLE SPECTRA OF PANI + 8% V2O5 (a)

Fig. 4.24 UV-VISIBLE SPECTRA OF PANI + 16% V2O5 (b)

4.4 X-Ray Diffraction
4.4.1 Introduction
Crystals are built up of small units having the same interfacial angles as the crystal. The distances between the atoms in crystals have been found to be roughly equal to 10-8 cm. So optical and electron microscopes can not be used in this field. X-rays diffracts by means of crystals, because the crystals acts as a three dimensional natural grating for X-rays, and X-rays acts as part of the em radiation with very small wavelength of the order of 10-8 cm. The X-ray diffraction (XRD) pattern depends upon the internal structure of crystal; hence this method is very useful for the structural study of the crystals. The application of XRD method to chemical analysis is primarily in the identification of compounds present from their diffraction pattern, and determination of relative concentrations by the intensities of pattern lines. This method provides information about the dimensions of unit cell of the crystal lattice and the atomic arrangement within the cell. XRD provides qualitative identification of crystalline compounds. This application based on the fact that the XRD pattern is unique for each crystalline substance and so chemical identity can be assumed, if an exact match can be found between the pattern of an unknown and an authentic sample. Qualitative identification of structures can be made by comparison of the interplaner spacing values of the specimen pattern with an index of standard pattern.
Diffraction data are also employed for the quantitative measurement of a crystalline compound in a mixture. The method may provide data that are difficult to obtain by other means. Quantitative analysis is carried out any comparing the intensity of a chosen diffraction line in a compound to the intensity of the same line in a standard mixture. Using this method, the unit cell parameters can be measured with high accuracy. Thus constitution of compounds in which there has been partial isomorphous replacement of one or more atoms in the unit cell can be accurately determined.
Basic Physical Properties of the polymers are governed by supra molecular structure. X-ray have become an important tools for the study of physical properties the matter in the solid state. They are also used to reveal the other characteristics such as crystal size, orientation and strain. Since the polymers cannot be completely crystalline, they do not have perfect crystal Lattice. According to original micellar37 theory of polymer crystallization, the polymeric material consists of numerous small crystallites, which are randomly distributed and linked by the intervening amorphous regions.
X-ray diffraction methods generally used for investigation of the internal structures, these are Laue photographic method, Bragg’s X-ray spectrometer method, rotating crystal method, and Powder crystal method. In the powder method, the crystal sample need not be taken in large quantity but ~ 1 mg of the material is sufficient for the study. This method was devised by Debye and Scherrer (Germany) 219.
The structure of polycrystalline material is investigated by means of the powder photograph method. In this method a beam of monochromatic X-radiations is incident on a polycrystalline sample in powder form. There will always be proportion of small crystal in the sample that is under the condition for which the Bragg’s formula is satisfied; since there may be tiny crystals (crystallites) are oriented randomly in the sample. Upon reflections from each set of parallel planes inside such crystallites for which 2dh,kl sin ? = n? is satisfied. The dependence of intensity of diffracted X-rays on the angle ? can also be obtained from X-ray diffraction pattern from the Debye-Scherrer photograph; and the d value can be calculated from Bragg’s formula
2d sin ? = n ? – – – – – -1,
Where, d is inter planer spacing, n is the order of reflection, ? is the wavelength of monochromatic X-rays, n is the order of reflection and ? is the glancing angle.
The identification of a structure from its powder diffraction pattern is based upon the position of lines (? or 2?) and their relative intensities. The diffraction angle, 2? is determined by the spacing between a particular set of planes. This distance d is readily calculated by making use of Bragg’s equation, provided wavelength of the source and measured angle are known. Line intensities depend upon the number and the kind of atomic reflection centres that exists in each set of planes. In general all polymers can be divided into two groups. The criteria for this classification are furnished by X-ray diffraction.
(a) Crystalline polymer: The type of polymer gives sharply defined set of reflections on X-ray photograph or maxima on diffraction pattern.
(b) Amorphous polymer: This type of polymer gives haloes instead of distinct reflections.
The powder method can be used to determine the degree of crystallinity of the polymer. The non crystalline portion simply scatters the X-ray beam to give a continuous background, while the crystalline portion causes diffraction lines that are not continuous. The amorphous material in the polymer will scatter at all wavelengths and give a scattered pattern; however, the crystalline material will include crystal structures and will produce definite diffraction lines. The ratio of the diffraction peaks to scattered radiation is proportional to the crystalline to noncrystalline material in the polymer. The ultimate quantitative analysis must be confirmed by using standard polymers with known crystallinities and basing the calculation on the known ratio of crystalline diffraction to amorphous scattering.
In orthorhombic case228, starting with a list of sin 2? values in ascending order, the first three reflections are assigned indices 100, 010, 001 respectively. These three values yield calculated values of lattice constant. These lattice constants are used to calculate the indices for further reflections. The chosen indices for those, whose calculated sin 2? values differ from the observed sin 2? values, less than the chosen error. The accepted set of indices gives the best sin 2? agreement. By interaction of this process, all reflections are indexed. For determination of lattice parameters following relations for orthorhombic case is used.
Sin2 ? h,k,l = ?2 h2 + ?2 k2 + ?2 l2
4a2 4b2 4c2

– – – — 2

and
Dhkl = 1
h2 + k2 + l2
a2 b2 c2

– – – — – 3

Many polymers show polycrystalline behavior, i.e. part of material forms an ordered crystallite by folding of the molecule. One and the same molecule may well be folded into two different crystallites and thus form a tie between the two. The tie part is prevented from crystallizing. The result is that the crystallinity will never reach 100%. Powder XRD can be used to determine the crystallinity by comparing the integrated intensity of the background pattern to that of the sharp peaks.
If the crystallites of the powder are very small the peaks of the pattern will broaden. From broadening it is possible to determine an average crystallite size, in Å, by Debye-Scherrer formula:
Dhkl = K ?
? cos ?
= 0.9 ?
? cos ?

– – – – – – – – – – – 4
Where, ? is wavelength of X-rays, ? is Bragg’s angle i.e. position of the maximum diffraction, K is a constant generally taken as unity e.g. 0.9 (k = 0.8 – 1.39), and ? is full width at half maximum of the peak (FWHM) i.e. ? (in radian unit) = half-width (degree) x ? / 180.

4.4.2 Experimental Technique
Now a days, commercial X-ray diffractometer use powder photograph technique for x-ray diffraction studies. Crystal structure, unit cell dimension and crystalline nature of the polymers can be studied by x-ray technique.
Powder diffraction is mainly used for identification of compounds by their diffraction patterns. A diffractometer utilized a monochromatic beam of radiation to yield information about d-spacing and impurities from crystalline powder. The structures of homopolymer and composites, and qualitative and quantitative phases are determined by the collected data from the XRD patterns of PANI and its composites. XRD patterns of PANI, and all its composites (Fig. 4.39 to 4.56) taken on X-ray diffractometrer PW 1710 Philips, Holland using radiation of wavelength (Cu- K?) 1.54056 and 1.54439 Å.

4.4.3 Observations and Calculations
The XRD crystallographic data (observed and calculated) of PANI, inorganic additives (V2O5, ZrO2, and PbS) and their composites is displayed on tables from 4.6 to 4.18 including calculated d-spacing and (h k l), and their calculated interchain lateral distances a, b, and c, cross section area for two chain i.e. A = a x b, and crystallite sizes Dhkl is given in table 4.19.

Table 4.6: XRD data of PANI

2? dobs dcal h k l I/I0
19.233
25.306
44.666
72.622 4.4651
3.5194
2.0288
1.3008 4.4651
3.5192
2.0285
1.3008 2 0 5
0 0 7
1 1 14
2 2 17 42.23
100.00
40.18
25.02
Table 4.8: XRD data of ZrO2

a= 5.1477, b= 5.2030, c= 5.3156 Å
2? dobs I/I0
24.186
28.230
31.423
34.159
40.783
45.092
50.165
55.503
60.006
62.651 3.6799
3.1613
2.8469
2.6249
2.2125
2.0106
1.8185
1.6556
1.5417
1.4816 24.42
100.00
66.41
29.00
16.03
16.07
31.29
19.84
16.03
12.97

Table 4.9: XRD data of PbS
a= 5. 9362 Å
2? dobs I/I0
25.999
30.111
43.112
51.010
53.463
62.560
68.959
71.027
78.999 3.4273
2.9679
2.0983
1.7904
1.7139
1.4835
1.3606
1.3260
1.2110 9.92
100.00
8.39
6.87
2.29
12.97
1.52
3.81
1.52

Table 4.7: XRD data of V2O5
a= 11.51, b= 3.559, c=4.371Å
2? dobs I/I0

15.396
20.295
21.712
26.157
31.026
32.388
34.326
41.584
44.701
47.336
51.270
55.926
58.733
61.173
72.564
5.7553
4.3757
4.0933
3.4069
2.8824
2.7642
2.6125
2.1718
2.0273
1.9204
1.7819
1.6441
1.5720
1.5150
1.3017
61.83
100.00
32.82
92.36
58.01
30.53
33.58
12.21
12.97
21.37
21.37
10.68
8.39
12.97
8.39

Table 4.10: Crystallographic data of PANI + 16% V2O5 (b)

2? dobs dcal h k l I/I0
19.233
20.823
23.331
24.538
26.012
26.731
27.678
29.689
30.086
32.347
33.166
34.230
37.327
39.539
41.680
43.088
43.754
44.545
45.975
50.962
53.593
56.900
62.066
68.627
70.999 4.6147
4.2659
3.8126
3.6278
3.4255
3.3349
3.2229
3.0091
2.9703
2.7676
2.7011
2.6196
2.4091
2.2792
2.1670
2.0994
2.0689
2.0297
1.9740
1.7919
1.7100
1.6182
1.4954
1.3675
1.3265 4.6147
4.2659
3.8118
3.6278
3.4256
3.3349
3.2229
3.0090
2.9703
2.7676
2.7012
2.6193
2.4091
2.2792
2.1670
2.0994
2.0689
2.0297
1.9740
1.7919
1.7100
1.6182
1.4954
1.3676
1.3265 8 8 35
17 5 0
0 7 17
4 0 0
11 12 42
0 0 7
6 0 29
0 11 16
12 14 43
9 0 22
9 0 29
10 0 21
0 23 14
9 0 35
17 13 0
20 0 17
0 28 16
0 26 17
16 16 0
20 16 0
0 21 26
13 34 0
0 22 31
0 32 28
22 0 35 9.07
78.95
56.97
33.02
77.01
100.00
91.29
86.68
81.28
29.93
36.85
7.25
13.29
11.91
22.17
30.08
74.02
68.84
13.17
33.60
10.63
7.56
9.63
7.23
10.91

Table 4.11: Crystallographic data of PANI + 24% V2O5 (c)

2? dobs dcal h k l I/I0
12.114
20.807
23.324
24.536
26.013
26.723
27.699
29.673
30.076
32.353
33.162
34.231
37.338
39.542
41.664
43.026
43.740
44.647
45.973
50.986
53.584
56.679
62.092
68.656
70.929 7.3060
4.2692
3.8139
3.6281
3.4254
3.3360
3.2205
3.0106
2.9713
2.7671
2.7014
2.6195
2.4083
2.2791
2.1677
2.1022
2.0696
2.0296
1.9741
1.7911
1.7103
1.6240
1.4948
1.3670
1.3276 7.3060
4.2692
3.8139
3.6281
3.4254
3.3360
3.2204
3.0104
2.9713
2.7667
2.7016
2.6195
2.4083
2.2790
2.1677
2.1025
2.0697
2.0295
1.9741
1.7911
1.7103
1.6241
1.4947
1.3670
1.3276 9 3 0
0 4 0
0 14 9
4 0 0
24 10 21
0 0 7
0 12 13
9 0 21
7 19 0
8 0 37
0 9 29
8 0 29
29 21 22
30 0 13
17 13 0
18 0 18
28 11 0
11 24 0
18 0 28
0 22 23
15 23 0
0 35 20
23 0 27
0 29 30
22 0 35 27.96
98.16
60.37
39.25
97.17
91.09
83.15
100.00
97.79
40.38
39.22
14.80
17.80
18.77
23.00
56.98
77.79
50.27
17.01
39.72
13.88
14.74
08.14
06.94
16.10

Table 4.12: Crystallographic data of PANI + 32% V2O5 (d)
2? dobs dcal h k l I/I0
10.187
11.647
13.594
16.934
21.532
22.171
25.191
44.693
72.680 8.6833
7.5980
6.5138
5.2357
4.1269
4.0094
3.5352
2.0276
1.2999 8.6833
7.5980
6.5133
5.2357
4.1269
4.0094
3.5352
2.0276
1.2998 0 2 0
0 0 3
5 19 8
3 0 0
24 5 0
5 20 0
24 9 24
26 0 16
26 25 0 10.40
26.23
10.38
13.27
12.79
11.95
100.00
60.0
35.57

Table 4.13: Crystallographic data of PANI + 16% ZrO2 (g)

2? dobs dcal h k l I/I0
20.799
25.390
28.249
31.427
34.218
40.746
44.721
50.144
53.971
55.479
59.852 4.2708
3.5079
3.1591
2.8465
2.6204
2.2145
2.0264
1.8192
1.6989
1.6563
1.5453 4.2711
3.5079
3.1591
2.8460
2.6210
2.2145
2.0264
1.8193
1.6989
1.6558
1.5453 0 14 17
0 0 6
5 0 0
10 14 0
0 25 11
0 8 0
38 11 0
0 15 33
14 31 0
17 0 29
32 0 20 7.01
34.91
100.00
64.73
24.40
9.88
14.77
24.78
9.11
11.78
6.81

Table 4.14: Crystallographic data of PANI + 24% ZrO2 (h)

2? dobs dcal h k l I/I0
24.224
28.176
31.502
34.083
40.701
44.688
50.217
55.338
59.921
62.618
3.6741
3.1671
2.8399
2.6306
2.2168
2.0278
1.8167
1.6601
1.5437
1.4835
3.6741
3.1671
2.8381
2.6306
2.2168
2.0279
1.8168
1.6602
1.5439
1.4835
0 0 6
5 0 0
14 27 21 15 0 14
0 8 0
38 11 0
36 0 16
0 29 21
27 0 23
28 0 24 18.08
100.00
54.39
21.73
10.76
15.89
23.01
12.15
11.31
6.08

Table 4.15: Crystallographic data of PANI + 8% PbS (k)
2? dobs dcal h k l I/I0
20.810
23.285
24.545
25.965
26.680
27.690
29.690
30.090
32.335
33.165
37.300
39.550
41.660
43.715
44.560
45.940
50.880
53.840
56.725
62.050
63.310
64.650
70.935 4.2756
3.8265
3.6328
3.4373
3.3462
3.2269
3.0140
2.9748
2.7732
2.7057
2.4147
2.2824
2.1715
2.0741
2.0367
1.9787
1.7976
1.7056
1.6255
1.4982
1.4714
1.4441
1.3308 4.2756
3.8289
3.6328
3.4373
3.3462
3.2269
3.0140
2.9748
2.7732
2.7057
2.4126
2.2829
2.1715
2.0740
2.0367
1.9787
1.7978
1.7056
1.6255
1.4980
1.4714
1.4441
1.3307 0 4 0
5 20 0
19 6 0
5 37 0
14 11 29
19 7 0
0 0 7
5 0 0
20 12 35
0 8 37
12 0 18
14 14 0
10 25 0
0 38 13
10 0 39
26 0 15
0 23 20
25 0 19
21 0 23
20 0 24
29 0 22
17 30 0
23 25 0 74.3
43.8
28.2
54.5
75.5
65.1
100.00
40.3
31.2
35.2
11.0
11.4
17.1
59.7
39.4
14.4
22.0
10.1
12.4
9.2
7.6
7.2
9.6

Table 4.16: Crystallographic data of PANI + 16% PbS (m)

2? dobs dcal h k l I/I0
7.725
19.255
20.805
23.330
24.600
25.140
25.590
26.745
27.695
29.685
32.307
33.175
34.240
37.310
39.540
41.715
43.775
44.655
45.975
48.385
50.895
53.845
56.710
62.100
64.655
66.605
68.595
78.230 11.4633
4.6172
4.2766
3.8192
3.6248
3.5482
3.4868
3.3388
3.2264
3.0145
2.7711
2.7049
2.6232
2.4141
2.2829
2.1688
2.0714
2.0326
1.9773
1.8843
1.7971
1.7054
1.6259
1.4971
1.4440
1.4064
1.3704
1.2240 11.4633
4.6172
4.2766
3.8188
3.6248
3.5482
3.4864
3.3388
3.2264
3.0123
2.7713
2.7049
2.6226
2.4141
2.2829
2.1688
2.0714
2.0359
1.9761
1.8867
1.7971
1.7054
1.6259
1.4971
1.4435
1.4064
1.3704
1.2223 7 2 26
0 9 8
0 4 0
15 6 0
4 0 0
7 35 22
5 0 37
5 39 0
12 13 31
14 0 11
7 0 31
0 9 27
30 8 0
0 0 9
0 28 13
9 0 39
7 0 0
0 18 20
0 0 11
17 0 21
0 29 18
13 29 0
14 29 0
0 37 21
27 0 24
27 0 25
17 0 42
0 14 0 19.3
11.1
79.9
54.4
29.1
15.8
51.3
100.00
78.6
95.8
39.8
44.4
10.2
12.6
14.7
21.3
67.7
44.4
16.3
8.5
12.6
13.1
12.1
14.7
6.5
7.3
6.9
6.2

Table 4.17: Crystallographic data of PANI + 24% PbS (m)

2? dobs dcal h k l I/I0
20.826
23.329
24.586
25.972
26.424
27.708
29.672
30.053
32.366
33.173
34.290
37.281
39.549
41.714
43.044
43.734
44.612
45.999
50.942
53.580
56.843
62.072
66.590
68.699
70.910 4.2654
3.8130
3.6209
3.4307
3.3358
3.2195
3.0108
2.9735
2.7660
2.7006
2.6152
2.4119
2.2787
2.1652
2.1014
2.0698
2.0311
1.9730
1.7926
1.7104
1.6198
1.4953
1.4044
1.3663
1.3279 4.2654
3.8130
3.6209
3.4307
3.3358
3.2195
3.0108
2.9736
2.7664
2.7009
2.6152
2.4119
2.2787
2.1653
2.1014
2.0693
2.0311
1.9731
1.7926
1.7101
1.6197
1.4953
1.4044
1.3663
1.3279 0 4 0
0 14 9
4 0 0
0 8 18
0 0 7
6 0 29
13 9 0
17 0 11
0 10 22
25 0 11
0 18 14
13 0 18
15 13 0
0 11 38
18 0 18
7 0 0
14 16 0
18 0 20
39 12 0
0 17 33
24 0 23
14 37 0
23 22 0
22 0 33
0 31 30 95.52

44.36
93.28
100.00
75.58
95.83
89.78
35.51

13.99
18.78
16.98
21.24
48.48
68.85
52.15
19.51
38.55
11.69
9.40
10.84
5.81
7.24
13.73

Table 4.18: Crystallographic data of PANI + 32% PbS (n)
2? dobs dcal h k l I/I0
12.165
18.680
20.055
20.795
23.345
24.530
25.175
25.575
25.955
26.715
27.670
29.655
30.080
31.985
32.330
33.170
34.245
37.315
39.515
40.735
41.705
43.055
43.730
44.635
45.940
50.960
52.485
53.815
56.680
62.045
64.595
65.225
66.655 7.2876
4.7580
4.4348
4.2787
3.8168
3.6350
3.5433
3.4888
3.4386
3.3425
3.2292
3.0175
2.9758
2.8028
2.7736
2.7053
2.6228
2.4138
2.2843
2.2187
2.1693
2.1044
2.0734
2.0335
1.9787
1.7950
1.7464
1.7063
1.6267
1.4983
1.4452
1.4328
1.4055 7.2876
4.7582
4.4342
4.2787
3.8168
3.6350
3.5433
3.4888
3.4386
3.3425
3.2292
3.0175
2.9758
2.8029
2.7730
2.7053
2.6228
2.4138
2.2843
2.2189
2.1693
2.1044
2.0734
2.0335
1.9787
1.7950
1.7464
1.7163
1.6263
1.4983
1.4452
1.4328
1.4055 4 14 9
0 32 5
10 7 42
10 4 0
7 33 18
5 26 0
14 20 13
12 35 12
0 6 36
0 6 43
19 7 0
0 0 7
5 0 0
19 13 30
14 10 0
8 0 25
21 16 25
29 9 0
26 10 0
28 17 31
20 12 0
25 0 14
23 12 0
11 0 31
0 30 15
0 18 25
0 19 25
0 18 28
0 0 13
0 25 26
17 30 0
24 0 26
0 23 32 22.0
6.3
32.7
96.0
53.0
37.5
19.6
45.4
47.2
100.00
75.8
98.6
67.8
11.6
28.2
42.6
17.2
14.5
20.2
7.4
24.0
22.7
84.3
51.0
20.2
21.4
6.7
13.5
15.6
13.0
7.8
6.0
9.4

Table 4.19

Samples d-spacing
Å Crystallite
Size Dhkl Å a
Å b
Å c
Å A = (a x b)
x 10-16 cm2
PANI

a
b
c
d
e

f
g
h
i
j

k
l
m
n 3.5194

3.5228
3.3349
3.0104
3.5352
3.5145

3.1631
3.1591
3.1671
3.1703
3.1764

3.0140
3.3388
3.3358
3.3425 103.416

127.192
691.446
835.095
129.236
84.8159

227.532
231.253
260.072
585.00
511.814

684.803
1022.058
829.71
583.15 16.6347

– – – – – –
14.5112
14.5128
15.7071
– – – – – –

– – – – –
15.7955
15.8355
– – – – –
– – – – –

14.8740
14.4992
14.4836
14.8790 17.4213

– – – – – –
17.0636
17.0768
17.3666
– – – – – –

– – – – –
17.7160
17.7344
– – – – – –
– – – – – –

17.1024
17.1064
17.0616
17.1148 24.9716

– – – – –
23.3443
23.3520
22.7940
– – – – – –

– – – – – –
21.0474
22.0452
– – – – –
– – – – –

21.0980
21.7315
23.3506
21.1225 289.79

– – – – – –
247.61
247.83
272.77
– – – – –

– – – – – –
278.25
280.83
– – – – – –
– – – – – –

254.38
248.02
247.11
254.65

4.4.4 Results and discussion:
The pure PANI exhibits its four characteristic peaks (may be assigned to the scattering from PANI chains at interplaner spacing154) at 2? angles around 19.2330, 25.3060, 44.660, and 72.62 0 (in table 4.6), out of which first two peaks are diffuse broad, which indicates that the PANI has crystallinity to a certain extent (polycrystalline). The significant crystallization of PANI by chemical oxidative route ensures the formation of PANI salt because it has amorphous nature in its base form229. The d-spacing is calculated from the 2? values which represents the characteristic distance between the ring planes of benzene ring in adjacent chains and it is also said to be the inter chain distance or the close contact distance between two adjacent chains84. XRD pattern of PANI under investigation well agree with reported data193,230. XRD patterns reveal that the structures of the polymers under study are polycrystalline because of some reflections and the diffused background. The crystal structures for PANI and composites are fond to be orthorhombic231. Hence it is considered that the unit cell dimensions a ? b ? c and ? ? ? ? ?.
Maximum intensity peak due to reflection from PANI structure is at 2? = 25.3070 for d- value 3.5194 Å shifts to high d-value upto 8% of V2O5 in composite, and with further increment upto 24% weight of V2O5 it shifts to lower d-value. For the samples, from ‘c’ to ‘e’ (24% to 40% wt of V2O5) this peak assigning PANI in composite shifts towards higher value of d-spacing again. In pure V2O5 structure its maximum intensity peak at 2? = 20.2950 correspond to 4.3757 Å value of d-spacing. This peak is absent in composite having 8% wt of V2O5. Same peak arises for increased weight % of V2O5 in composite (sample ‘b’ and ‘c’) with shifting towards high value of d-spacing. For further increment in wt % of V2O5 in composites (samples’d’ and ‘e’) the peaks assigning V2O5 structure vanishes. Peaks assigning the identity of PANI and V2O5 shifts and shows variations in their intensity with increasing wt% of V2O5 in composites ensure the intercalation of PANI in V2O5 structure by two different phases123. High crystallinity is observed for these composites for 16 to 24 wt % of V2O5 in composites. Remaining PANI/ V2O5 composites shows very low crystallinity approaching towards amorphous nature.
In XRD patterns of PANI/ZrO2 series from ‘f’ to ‘j’, the maximum intensity peak of PANI shifts towards shorter d-values with decrease in their intensity from pure PANI to composite which consist 8% wt of ZrO2. For further increment in wt% of ZrO2 in composites, from 8% to 32%, maximum intensity reflection from PANI slightly shifts to high d-values with large decrement in their intensity, and laps for composite having 40% weight of ZrO2. The maximum intensity peak, assigning ZrO2, slightly shifts to shorter d-value, from pure ZrO2 to 8% wt of ZrO2 in composite. For further increment in percent weight of ZrO2 this peak shows slight shifting towards high d-value. This shifting of high intensity peak indicates the interaction of ZrO2 with PANI structure in composites. These composites show high crystallinity for 16 to 24 wt %of ZrO2 in it. Remaining samples approaches to amorphous nature. When ZrO2 particles is incorporated into PANI, the broad diffraction peaks of the PANI become very weak, and the diffraction pattern of composite PANI/24% ZrO2 become like as that of ZrO2 diffraction pattern. Near about same situation is observed for PANI/ V2O5 and PANI/PbS composites.
In case of PANI/PbS samples (‘k’ to ‘n’), the identity reflections of maximum intensity assigning PANI, shifts toward shorter d-value and that of PbS shifted towards longer d-values. Its crystallinity increases and become high for 24% wt of PbS in composite. For further increment of wt% of PbS, the crystallinity of composites decreases, approaching to amorphous nature.
In case of all composites, the crystallite size increases with increase in weight % of additives up to 24%, and decreases for further increment of weight % of additives. There may be some error in calculated crystallite sizes as reported for Debye-Scherrer formula – – 4.
Most of the composites show their polycrystalline nature except few of them which acquired very less crystallinity. Each series of composites shows composite of high crystallinity for net 16% to 24% weight of additives (V2O5, ZrO2, and PbS) in PANI. Observed varying crystallinity of samples with changing impurity percentage in composites suggests the considerable interfacial interactions of additives with PANI. It is more probable to change the interchain distance with addition of inorganic impurities in pure PANI structure and consequently the changed delocalization length. This is very crucial and favorable fact to obtain changed electrical conductivity of PANI composites with variation in added weight % of inorganic species like V2O5, ZrO2, and PbS. The d-spacing values and lattice parameters a, b, and c of composites are differ from those of PANI. Also these values of d-spacing and lattice parameters are varied with weight % of additives. The values of d-spacing of PANI and composites show that their local chain arrays are similar193. The inter-chain lateral distance, a and b gives the cross section area for two chains i. e. A = a x b. For all samples, large value of c confirms that the C-N-C angle is larger. This increase may be due to steric interaction between H and the substituted group of benzene ring37.

Fig. 4.39- XRD spectra of PANI

Fig. 4.40- XRD spectra of V2O5

Fig. 4.41- XRD spectra of PANI + 8%V2O5 (a)

Fig. 4.42- XRD spectra of PANI + 16%V2O5 (b)

Fig. 4.43- XRD spectra of PANI + 24%V2O5 (c)