Synthesis and Characterization of Novel Θ-Type Zirconium Phosphate-Crystalline Cerium Phosphate/ Polyaniline, Polyindole, Polycarbazole, Polyaniline-co-Polyindole, and Polyaniline-co-Polycarbazole Composites

Θ-Type zirconium phosphate, Θ-Zr(HPO 4 )2-.1.77H 2 O (Θ-ZrP), crystalline cerium phosphate, Ce(HPO 4 ) 2 .1.33 H 2 O (CePc), and [Θ-Zr(HPO 4 ) 2 ] 0.30 [Ce (HPO 4 ) 2 ] 0.70 .2H 2 O composite were prepared and characterized by chemical, XRD, TGA, FT-IR and scanning electron microscopy(SEM). [Ɵ-Zr(HPO 4 ) 2 ] 0.30 [Ce(HPO 4 ) 2 ] 0.70 /polyaniline, polyindole, polycarbazole, polyaniline-co-polyindole, polyaniline-co-polycarbazole composites were prepared via in-situ chemical oxidation of the monomers aniline , indole , carbazole and (1:1moler ratio) of co-monomers aniline-indole, aniline-carbazole, respectively, that was promoted by the reduction of part of Ce(IV) ions present in the inorganic matrix. A possible explanation is part of CePc is attacked by the monomers, and the co-monomers, respectively, converted to cerium (III) orthophosphate (CePO 4 ). The resultant novel composites were characterized by elemental (C,H,N) analysis, FT-IR, and (SEM). From elemental (C,H,N) analysis ,the amount of organic materials present in [Θ-Zr(HPO 4 ) 2 ] 0.30 [Ce (HPO 4 ) 2 ] 0.70 / polyaniline, polyindole, polycarbazole composites were (23.44, 5.24 and 33.02 % in wt. ), respectively. The amount of resultant copolymers were (Pani 5.92, PIn 7.48 % in wt) and (Pani 1.42, PCz 2.48 % in wt ) These composites can be considered as novel conducting inorganic-organic composites, ion exchangers , solid acid catalysts and sensors.

Crystalline cerium phosphates have been studied as ion exchangers, intercalates and as proton conductance. Their composition, structure and the degree of crystallinity results from reaction of solutions containing a Ce IV salt is mixed with a solution of phosphoric acid of [(PO 4 )/Ce IV ratio] [17][18][19], strongly dependent on the experimental conditions such as rate and order of mixing of the solutions, stirring, temperature and digestion time [20][21][22].
Composite materials have been the target of growing interest owing to their unique optical, electrical, mechanical, thermal, and magnetic properties arising from the combination of the different constituents on a nanometric scale. In recent years, several organic-inorganic nanocomposites have been prepared by combining organic polymers and inorganic materials, employing different methods. In some cases, a polymer is introduced into the free spaces of the inorganic compound interlayer spaces in layered solids [23][24][25][26].
Introduction of monomer molecules and their further polymerization in confined environments can also be performed [23][24][25][26]. Another approach involves the coating of core-like particles of inorganic oxides, glass fibbers, etc. This can be achieved either by adsorption of polymers on the particles or by adsorption of monomers in the cores, followed by polymerization [27][28][29][30].
Conducting polymers are a novel class of synthetic metals , called materials of 21 st Century , that combine the chemical, electrochemical and mechanical properties of polymers with the electronic properties of metals and semiconductor, generated tremendous interest due to their potential applications in various fields such as rechargeable batteries, electrochromic display devices, separation membrane sensors and anticorrosive coatings on metals [23,25,27,29,[31][32][33][34][35][36]. Their methods of preparation were carried out mainly by chemical oxidation polymerization and electrochemical polymerization [37][38][39].
The biggest advantage of conducting polymers is their process ability, low cost, and thermal stability [37,38]. They have alternating single and double bonds in their conjugated molecules. On doping these conjugated polymers show very high conductivity similar to metal.
Polycarbazole, although less studied among the conductive polymers, has many advantages such as cheap, environmental and chemically stable because of aromatic structure with nitrogen atom in structure. It has unique electrical, electrochemical and optical properties [62][63][64]. Novel nanocomposites of polybenzimidazole, polyaniline and their copolymers polypyrrole, polyindole have been reported recently [65,66].

Instruments Used for Analysis
 X-ray powder diffractometry. Siemens D-500, using Ni-filtered CuK a (λ=1.54056A ᶱ ) XRD with CuK a radiation at 1.540Å by using PHILIPS PW1710.

Preparation of Ө-Type Zirconium Phosphate
50ml 0.5M ZrOCl 2 .8H 2 O in 3M HF were mixed with 200ml of (4.6M) H 3 PO 4 in Pyrex round bottom flask (prior to mixing, the solutions were cooled at ~15ºC),. The mixture left at ~15ºC for 3days. The resultant precipitate was washed with distilled water, by addition and decantation of distilled water, up to pH3.The resultant product was filtered and left to dry in air.

Preparation of Crystalline Cerium Phosphate
100g of CeSO 4 .4H 2 O were dissolved in 400ml of 10M H 3 PO 4 under stirring at 80 o C in a glass round bottom flask. The product starts to form after few hours of stirring at that temperature, and left to digest for 4daysat 80 o C. The resultant precipitate was subjected to washing by distilled water up to pH=3.5, filtered and air dried to obtain crystalline cerium phosphate.

Preparation of Θ-Type Zirconium Phosphate-Crystalline Cerium Phosphate Composite (Θ-ZrP-CeP c )
0.1g of Θ-ZrP was mixed with 0.25g of CePc in10ml ethanol, with stirring for 15 minutes at room temperature. The resultant product was filtered, washed with ethanol and left to dry in air.
Preparation of Θ-Type Zirconium Phosphate-Crystalline Cerium Phosphate/Polyaniline Composite, (Θ-ZrP-CeP c /Pani) 0.1g of Θ-ZrP was mixed with 0.25g of CeP c in 10ml of ethanol with stirring for 15 minutes at room temperature, to that 13ml 4% aniline in ethanol was added with stirring for 48hr at room temperature. The resultant product was filtered, washed with ethanol and left to dry in air. The colour of the resultant product was bluish-green.

2.6.2.
Preparation of Θ-Type Zirconium Phosphate-Crystalline Cerium Phosphate/Polyindole Composite, (Θ-ZrP-CeP c /PIn) 0.1g of Θ-ZrP was mixed with 0.25g of CeP c in 10ml ethanol with stirring for 15 minutes at room temperature, to that 16.5ml 4% indole in ethanol was added with stirring for 48hr at room temperature. The resultant product was filtered, washed with ethanol and left to dry in air. The colour of the resulting product was brownish-green.

2.6.3.
Preparation of Θ-Type Zirconium Phosphate-Crystalline Cerium Phosphate/Polycarbazole Composite, (Θ-ZrP-CeP c /PCz) 0.1g of Θ-Type ZrP was mixed with 0.25g of CeP c in 10ml of ethanol with stirring for 15 minutes at room temperature, to that 23ml 4% carbazole in acetone solution were added with stirring for 48hr at room temperature. The resultant product was filtered, washed with acetone and left to dry in air. The colour of the resultant product was green.

Polymerization of Aniline-co-Indole and Aniline-co-Carbazole by Θ-Type Zirconium Phosphate-Crystalline Cerium Phosphate Composite 2.7.1. Preparation of Θ-Type Zirconium Phosphate Crystalline Cerium Phosphate / Polyaniline-co-Polyindole Composite, (Θ-ZrP-CeP c /Pani-co-PIn)
A mixture of 0.1g of Θ-Type ZrP and 0.25g of CeP c was dispersed in 10ml ethanol with stirring for 15 minutes, to that mixture of 6.5 ml 4% aniline in ethanol and 8.5ml 4% indole in ethanol was added. The stirring was continued for 48hr at room temperature (20 o C). The resultant product was filtered, washed with ethanol and left to dry in air. The colour of the product was bluish-green.

Preparation of Θ-Type Zirconium Phosphate -Crystalline Cerium Phosphate/Polyaniline-co-Polycarbazole Composite, (Θ-ZrP-CeP c /Pani-co-PCz)
A mixture of 0.1g of Θ-Type ZrP and 0.25g of CeP c was dispersed in 10ml ethanol with stirring for 15 minutes, to that mixture of 6.5 ml 4% aniline in ethanol and 11.5ml 4% carbazole in acetone was added. The stirring was continued for 48hr at room temperature (20 o C). The resultant product was filtered, washed with ethanol and acetone, then left to dry in air. The colour of the product was bluish-green.

Results and Discussion
Different composition structures of crystalline zirconium phosphate and cerium phosphates, Zr(HPO 4 ) 2 .nH 2 O, Ce(HPO 4 ) 2 .nH 2 O , where n=1-5 and 1-3, respectively, results from reaction of solutions containing a Zr IV and Ce IV salts with phosphoric acid, found to be strongly dependent on the experimental conditions. In previous studies we have found that when nanofibrous cerium phosphate membrane, Ce(HPO 4 ) 2 .2.9H 2 O, reacts with aniline the resultant product was polyaniline nanocomposite membrane , of black color, non-conductance [67]. However , when dilute HCl solution was added during the process of polymerization, the resultant product was Emiraldine salt nanocomposite, green color. Nanofibrous cerium phosphate act as self-support polymerization of aniline while dilute HCl act as doping agent [67]. From that we plan to arrange facile synthesis of conducting polymers cerium phosphate composites using self-support doping agent combined with cerium phosphate. Zirconium phosphates contains labile proton (H + ) present in its (POH) groups found to be the best choice for self doping.
Θ-Type zirconium phosphate, Θ-Zr(HPO 4 ) 2 .1.77H 2 O, was prepared from reaction of tetravalent zirconium salt, ZrOCl 2 .8H 2 O and H 3 PO 4 in HF solution. The resultant product was characterized by chemical, XRD, thermal analysis and by FT-IR spectroscopy. Its exchange capacity was determined by Na + ions titration. Figure 1 shows the X-ray powder diffraction pattern of the Θ-type zirconium phosphate, with presence of diffraction maxima, basal spacing equal 9.85Å. The Θ-type material exhibit lamellar structure. Negatively

TG/DTA of Θ-ZrP
Thermal analysis of Θ-type Zr(HPO4)2.1.77H2O is shown in Figure 3, was carried out at temperature range 25-800℃ in air atmosphere. The heating rate was 10ºC/min. The thermal decomposition exhibits two weight loss stages, the loss of water of hydration followed by POH groups condensation. The final product was ZrP 2 O 7 . The thermal decomposition found to follow the same trends of thermal decomposition of tetravalent metal phosphates [1][2][3]. The thermal decomposing was accompanied by endothermic peaks.

Exchange Capacity of Θ-ZrP
Exchange capacity of Θ-type zirconium phosphate was determined by Na + ions titration. The titration curve is shown in Figure 4. The exchange capacity found to be equal to 6.2Meq/g. The calculated value is 6.01Meq/g. The difference is due to partial hydrolysis of HPO 4 groups due to pH effect.

XRD of CePc
X-ray diffraction pattern of crystalline cerium phosphate is shown in figure 5, its interlayer distance found to be equal to 16.05Ǻ.

FT-IR of CePc
FT-IR spectrum of crystalline cerium phosphate is given in Figure 6. It consist of broad band centered at ~3377cm -1 attributed to OH groups and symmetric stretching of H 2 O. Small sharp band at 1656 cm -1 is due to H-O-H bending. Sharp broad band centered at 1055cm -1 is related to the phosphate groups vibration.

TGA of CePc
Thermal analysis of crystalline cerium phosphate is shown in Figure 7, was carried out at temperature range 25-900℃ in air atmosphere. The heating rate was 10ºC/min. the water of hydration loss occurs in the temperature range 70-250 0 C. Above that POH groups condensation occurs. The final product was CeO 2 .P 2 O 5.

SEM of CePc
SEM morphology image of crystalline cerium phosphate is shown in Figure 8. The photograph shows its form , mainly, of compact crystallites.

Exchange Capacity of CePc
Exchange capacity of crystalline cerium phosphate was determined by Na + ions titration. The titration curve is shown in Figure 9. The exchange capacity found to be equal to 2.5Meq/g.  30 [Ce(HPO 4 ) 2 ] 0.70 /polyaniline-, ?polyindole and / polycarbazole composites. A possible explanation is part of CePc is attacked by the monomers, respectively, converted to cerium (III) orthophosphate (CePO 4 ). During the reaction the colour gradually changes with time to bluish-green, brownish-green and green, respectively.

FT-IR Spectra of Θ-ZrP-CePc/ Polyaniline-Polyindole-, Polycarbazole composites
FT-IR spectroscopy became a key tool to investigate structure of conductive polymers and their composites. Figures 13, 14, 15 show FT-IR spectra of Θ-ZrP-CePc/polyaniline-, /polyindole-, and /polycarbazole composites, respectively, consisting of similarity of major bands. Broad band in the range 3500-2850cm -1 centered ~3 125cm -1 , is related to OH groups symmetric stretching of H 2 O super imposed with the N-H stretching of aromatic amines. Medium sharp band around~ 1600cm -1 is related to H-O-H bending, and sharp band, centered at ~1 025cm -1 corresponds to phosphate groups (PO 4 ) vibration. Bands in the range 2250-1250cm-1 correspond to C-H bonds and to the non-symmetric C 6 ring stretching modes. However the higher frequency vibration at ~1 500cm −1 has a major contribution from vibration of quinoid ring of polyaniline. Other bands in the same region range are related to C-C bonds C-H (aromatic) stretching, C=C stretching. and C-N stretching of the resultant composites.  3.11.1. SEM Images of Θ-ZrP-CePc/Polyaniline-co-Polyindole-, Polyaniline-co-Polycarbazole Composites SEM morphology images of Θ-ZrP-CePc / polyaniline-co-polyindole and polyaniline-co-polycarbazole composites are shown in Figures 16, 17, respectively, reveal a distribution of the copolymer on the inorganic matrix (Θ-ZrP-CePc). Consists of broad band in the range 3600-2800cm -1 centered ~3 250cm -1 is due to OH groups symmetric stretching of H 2 O super imposed with the N-H stretching of aromatic amines . Medium sharp band around ~1 605cm -1 is related to H-O-H bending, sharp band ,centered at 1056cm -1 corresponds to phosphate groups (PO 4 ) vibration. Small band at ~2 500cm -1 corresponds to C-H bonds. However the higher frequency vibration at ~1 495cm -1 has a major contribution from vibration of quinoid ring, of polyaniline . Other bands in the range ~2 400-1200cm -1 correspond to the non-symmetric C 6 ring stretching modes , C-C bonds, C-H (aromatic) stretching, C=C stretching and C-N stretching. Consists of broad band in the range 3600-3000cm -1 centered ~3 250cm -1 is due to OH groups symmetric stretching of H 2 O super imposed with the N-H stretching of aromatic amines . Medium sharp band around ~1 605cm -1 is related to H-O-H bending, sharp band ,centered at 975cm -1 corresponds to phosphate groups(PO 4 ) vibration. Small band at ~2 150cm -1 corresponds to C-H bonds. Other bands in the range ~1 500 -1150cm -1 correspond to the non-symmetric C 6 ring stretching modes, C-C bonds, C-H (aromatic) stretching, C=C and stretching. C-N stretching.   30 [Ce(HPO 4 ) 2 ] 0.70 / polyaniline, polyindole, polycarbazole, polyaniline-co-polyindole and polyaniline-co-polycarbazole composites were prepared via in-situ chemical oxidation of the monomers aniline, indole, carbazole, respectively, and their co-monomer, respectively, that was promoted by the reduction of part of Ce(IV) ions present in the inorganic matrix. A possible explanation is part of CePc is attacked by the monomers, and the co-monomers, respectively, converted to cerium (III) orthophosphate (CePO 4 ). The resultant composites were characterized by elemental (C,H,N,) analysis, FT-IR and SEM. The formulation of the resultant novel conducting polymers and copolymers composites was supported by elemental (C,H,N) analysis, FT-IR spectra ,SEM and by colour changes. We suggest self doping occurred on polymerization, which is due to labile proton (H + ) present in (POH) groups of Θ-ZrP/CeP c composite. These composites can be considered as novel conducting inorganic-organic composites, ion exchangers, solid acid catalysts and sensors.