- Email: [email protected]
PANI nanocomposites through hydrothermal synthesis coupled with in situ polymerization
Composites Science and Technology 99 (2014) 147–153
Contents lists available at ScienceDirect
Composites Science and Technology journal homepage: www.elsevier.com/locate/compscitech
Preparation of magnetic-conductive Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites through hydrothermal synthesis coupled with in situ polymerization Jie Zhao a, Yu Xie a,⇑, Mingjun Li a, Fangcheng Xu b, Zhanggao Le c,⇑, Yuancheng Qin a, Dan Zhou a, Zhenguo Wang d, Hai Xu a, Jianfei Pan a, Yun Ling a a
Department of Materials Chemistry, Nanchang Hangkong University, Nanchang 330063, PR China College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, PR China c Department of Applied Chemistry, East China Institute of Technology, Fuzhou 344000, PR China d Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, PR China b
a r t i c l e
i n f o
Article history: Received 25 February 2014 Received in revised form 11 May 2014 Accepted 13 May 2014 Available online 23 May 2014 Keywords: A. Functional composites A. Nanocomposites A. Polymer–matrix composites B. Magnetic properties B. Electrical properties
a b s t r a c t A facile chemical method through hydrothermal synthesis coupled with in situ polymerization to prepare the Mn0.6Zn0.4Fe2O4-carbon nanotubes (CNTs)/polyaniline (PANI) nanocomposites has been reported in this paper. The structure of samples has been characterized by the Fourier transform infrared and Xray diffraction. The shape and size of samples have been observed by the scanning electron microscopy and transmission electron microscopy. The conductive properties of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites have been tested by a four-probe conductivity tester at room temperature. And the magnetic properties are measured by a vibrating sample magnetometer. When the mass ratio of the Mn0.6Zn0.4Fe2O4-CNTs to aniline (m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An)) is 0.15, the Ms, Mr and Hc achieves 15.44 emu/g, 5.06 emu/g and 308.68 Oe, respectively. At the same time the probable formation mechanism of nanocomposites is also investigated based on the experimental results. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Researches on the inorganic–organic conductive-magnetic nanocomposites have attracted more and more attentions [1–8]. Combining magnetic particles and conductive polymers is a workable route to prepare the conductive-magnetic nanocomposites [9,10]. Due to the unique electrical, easy preparation, excellent environment stability, optical and optoelectrical characteristics, the polyaniline (PANI) has become one of the most popular conductive polymers [11]. Li’s group has prepared a series of the magnetic particles-PANI composites using an in situ polymerization [12–15]. Wan et al. has synthesized a novel cage-like and electromagnetic functional PANI/CoFe2O4 nanocomposites by a self-assembly process. The cage-like composites possess high conductivity (rmax5.2 S/cm) and typical ferromagnetic behaviors [16]. In addition, CNTs have been characterized by the nanometric dimension, high aspect ratio, chemical stability, high Young’s
⇑ Corresponding authors. Tel./fax: +86 (791) 83953373 (Y. Xie). E-mail addresses: [email protected] (Y. Xie), [email protected] (Z. Le). http://dx.doi.org/10.1016/j.compscitech.2014.05.023 0266-3538/Ó 2014 Elsevier Ltd. All rights reserved.
modulus and interesting electrical properties, especially large permittivity [17–19]. Zhao et al. using in situ sol–gel method has connected the magnetic nanoparticles onto the surface of CNTs preparing the CNTs-magnetic nanoparticles. The size of magnetic nanoparticles is at the nanometer level [20,21]. Therefore, a general approach has been proposed as follows. Firstly, magnetic particles are formed and absorbed onto the surface of CNTs through the hydrothermal synthesis reaction. Then aniline (An) monomers will get together forming PANI onto the surface of the magnetic particles coated CNTs through in situ polymerization. In this paper, we have coupled with hydrothermal synthesis and in situ polymerization to successfully prepare the magneticconductive Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. The structure, morphology, conductive properties and magnetic properties of the composites have also been characterized. This study may have provided a general approach to synthesize the ternary composites of the MXNYFe2O4 (M, N = Mn, Zn, Li, Ni, Cr, La, Ba, et al.; X + Y = 1)-CNTs/conductive polymers. At the same time, it also contributes to investigate and reveals the exchange interactions among magnetic particles, CNTs and conductive polymers, as well as the relations of the conductive performances and the magnetic properties.
148
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153
solution stirring for 12 h. After that, the suspension was filtered and the residue was washed with absolute ethanol and deionized water, respectively. The obtained product was dried under vacuum at 60 °C for 10 h.
2. Experiment 2.1. Materials In this study, aniline (C6H5NH2, An, AR, 99.5%) and dodecylbenzene sulfonic acid (C18H30O3S, DBSA, 90%) were purchased from Aladdin Chemistry Co. Ltd. CNTs (Multiwalled; OD 20–30 nm; Length 10–30 lm; Purity >95% (Raman); Ash <0.5 wt.%; SSA >200 m2/g; EC >102 S/cm) were purchased from Beijing DK Nano Technology Co. Ltd. Other chemicals were analytical reagent. 2.2. Synthesis of PANI 1.0 g An was added into 20 mL 1 mol/L HCl stirring for 1 h at 5 °C. 10 mL 1 mol/L (NH4)2S2O8 was slowly dropped into the above
2.3. Preparation of the Mn0.6Zn0.4Fe2O4-CNTs CNTs were treated by 14.5 mol/L nitric acid at 60 °C for 30 min. 2.0 g treated CNTs were added into 50 mL deionized water under ultrasonic dispersing for 1 h. Then, 4.0 g DBSA was added into the above solution under ultrasonic dispersing for 2.5 h. The suspension was filtered, and the residue was washed with deionized water until the pH of the filtrate to 7. The product was dried under vacuum at 50 °C for 24 h. After that, the modified CNTs by DBSA were obtained. 0.20 g MnSO4H2O, 0.24 g Zn(NO3)26H2O and
Table 1 The stoichiometric amounts of every material used to prepare the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposite.
Mn0.6Zn0.4Fe2O4-CNTs/PANI with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05 Mn0.6Zn0.4Fe2O4-CNTs/PANI with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.10 Mn0.6Zn0.4Fe2O4-CNTs/PANI with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.15
Mn0.6Zn0.4Fe2O4-CNTs (g)
Aniline (g)
(NH4)2S2O8 (mL)
0.05 0.10 0.15
1.0 1.0 1.0
10 10 10
Fig. 1. The proposed preparation scheme of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites.
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153
149
3. Results and discussion 3.1. Proposed preparation scheme of the nanocomposites
Fig. 2. FTIR spectra of (a) PANI, (b) CNTs, (c) Mn0.6Zn0.4Fe2O4-CNTs and (d) Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites.
1.62 g Fe(NO3)39H2O were dissolved into 50 mL deionized water. Then, 1.0 g modified CNTs were added into the above solution under ultrasonic dispersing for 0.5 h. 10 mol/L NaOH was slowly dropped into the mixed solution within 0.5 h until pH > 8. And then, the mixed solution was layered. The supernatant was removed, and the precipitate was transferred into reaction kettle at 180 °C for 5 h. After completion of the reaction, the system was cooled to room temperature, and the solution was filtered. The residue was washed with absolute ethanol and deionized water, respectively. Finally, the products were dried under vacuum at 60 °C for 24 h. 2.4. Preparation of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites 1.0 g An and 0.05 g the Mn0.6Zn0.4Fe2O4-CNTs were added into 35 mL 0.1 mol/L HCl stirring for 30 min forming solution A. 10 mL 1 mol/L (NH4)2S2O8 was added into 15 mL 0.1 mol/L HCl forming solution B. Solution B was slowly added into solution A stirring for 12 h at 5 °C. After that, the mixed solution was filtered, and filtered matter was washed with absolute ethanol and deionized water, respectively. The product was dried under vacuum at 60 °C for 24 h. Changing the mass ratio of the Mn0.6Zn0.4Fe2O4CNTs to An and according with the above method, the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites were obtained with different m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05, 0.10 and 0.15, respectively. The stoichiometric amounts of every material used to prepare the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites have been listed in Table 1.
Fig. 1 illustrated a simple preparation process of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. CNTs were oxidized by nitric acid and DBSA, respectively. After that, there were a large number of -COO-, -OH and sulfonic acid groups onto the surface of CNTs. Then, Fe3+, Mn2+ and Zn2+ ions were self-adsorbed by the ACOO and sulfonic acid groups. The Mn0.6Zn0.4Fe2O4 was formed onto the surface of CNTs at 180 °C for 5 h. Immediately, a large number of Cl was adsorbed onto the surface of Mn0.6Zn0.4Fe2O4. And then, the An molecules were adsorbed onto the surface of the Cl and CNTs through electrostatic attraction and p–p interactions, respectively. Finally, under (NH4)2S2O8 initiator, the in situ polymerization reaction of An was carried on. The Mn0.6Zn0.4Fe2O4-CNTs/ PANI nanocomposites had been successfully synthesized, and the characterization discussed below.
3.2. FTIR analysis Fig. 2 shows the FTIR spectra of PANI, CNTs, Mn0.6Zn0.4Fe2O4CNTs and the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. In Fig. 2(a), the characteristic peaks of PANI are at 1559, 1489, 1292, 1104, 793, 613 and 502 cm 1 with slightly movement compared with the literature [16]. The peaks at 1559 and 1489 cm 1 are attributed to the characteristic C@C stretching of the quiniod and benzenoid rings. 1292 cm 1 is assigned to CAN stretching of secondary aromatic amine. The broad peak at 1104 cm 1 which is described by MacDiarmid et al. as the ‘electronic-like band’ is assigned to the vibration mode of N = Q = N. It indicates that PANI has been synthesized successfully in our samples [22]. 793, 613 and 502 cm 1 could be assigned to the out-of-plane rocking vibration of @CAH group in the 1,4-disubstituted benzene ring. And the peak at 3448 cm 1 is related to water molecules. From Fig. 2(b), the characteristic peak of CNTs is weak at 1637 cm 1 due to C@C symmetrical stretching vibration. The characteristic absorption peaks of the Mn0.6Zn0.4Fe2O4-CNTs are at 1578, 1385, 1125, 1062, 605 and 472 cm 1 in Fig. 2(c). Compared with Fig. 2(b), after modification by ACOO , AOH and DBSA, obvious peaks at 1578, 1385, 1125 and 1062 cm 1 can be found. The stronger 1578 cm 1 peak may be due to C@C stretching of benzenoid ring of DBSA on the surface of CNTs. 1385 cm 1 is attributed to C@O stretching vibration, and the peak at 1125 cm 1 can be assigned to CAC stretching vibration. Peak at 1062 cm 1 is related to AOAH group. The new peaks at 605 and 472 cm 1 are attributed to Fe(Mn or Zn)AO stretching
2.5. Characterization Fourier transform infrared (FTIR) spectra was obtained using Nicolet 5700 FTIR with KBr method. X-ray diffraction (XRD) patterns of the samples were characterized by using a philpspw3040/60 diffractometer with Cu Ka radiation (k = 0.15418 nm). The morphologies and the microstructure of the synthesized samples were observed by a scanning electron microscopy (SEM, Nova NanoSEM450) and a transmission electron microscope (TEM, JEOL JEM2010), respectively. The electrical conductivities were carried out on a four-probe resistivity instrument (SDY-4) at room temperature using pressed pellets of sample’s powder with the thickness of about 1 mm and diameter of 20 mm under 70 MPa. A Lakeshore 7404 vibrating sample magnetometer was used to measure the magnetization of the samples in applied magnetic fields over the range of 10 to +10 kOe at room temperature.
Fig. 3. XRD patterns of (a) PANI, (b) CNTs, (c) Mn0.6Zn0.4Fe2O4-CNTs and (d) Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites.
150
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153
vibration. This indicates that Mn0.6Zn0.4Fe2O4 has been formed onto the surface of CNTs through r–p conjugated interactions. In Fig. 2(d), the characteristic absorption peaks of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites are at 1574, 1493, 1298, 1139, 818, 694 and 508 cm 1. The peaks at 1574, 1493, 1298, 1139, 818 and 694 cm 1 can be assigned to characteristic peaks of PANI with slightly blue-shift compared with Fig. 2(a). This indicates that there are some r–p and p–p interactions among Mn0.6Zn0.4Fe2O4, CNTs and PANI. And 508 cm 1 in Fig. 2(d) can be attributed to Mn0.6Zn0.4Fe2O4 characteristic peak. Therefore, the Mn0.6Zn0.4 Fe2O4-CNTs/PANI nanocomposites have been synthesized successfully.
assigned to the Mn0.6Zn0.4Fe2O4 characteristic peaks. This indicates that there are interactions between Mn0.6Zn0.4Fe2O4 and CNTs. In Fig. 3(d), the characteristic peaks of the Mn0.6Zn0.4Fe2O4-CNTs/ PANI nanocomposites are at 2h = 15.4°, 19.6° and 25.7°. However, the characteristic peaks of Mn0.6Zn0.4Fe2O4 and CNTs are disappeared due to the small mass ratio of m(Mn0.6Zn0.4Fe2O4-CNTs) to m(An). The diffraction peaks of Mn0.6Zn0.4Fe2O4 and CNTs have been covered by the PANI diffraction peaks in the Mn0.6Zn0.4Fe2O4CNTs/PANI nanocomposites. This indicates that Mn0.6Zn0.4Fe2O4 and CNTs are wrapped in the PANI through r–p and p–p interactions. Therefore, the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites have been synthesized successfully in our paper and the morphology analysis discussed below.
3.3. XRD analysis 3.4. Morphology analysis Fig. 3 shows the XRD patterns of PANI, CNTs, the Mn0.6Zn0.4 Fe2O4-CNTs and the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. In Fig. 3(a), the PANI characteristic diffraction peaks are at 2h = 15.3°, 20.4° and 25.4° with slightly different from the reported [16]. 2h at 20.4° and 25.4° can be assigned as planes perpendicular and parallel to the polymer chain, [23,24] respectively. In Fig. 3(b), the CNTs characteristic peak is at 2h = 26.1° can be ascribed to the (0 0 2) reflection [25]. From Fig. 3(c), the characteristic peaks of the Mn0.6Zn0.4Fe2O4-CNTs are at 2h = 26.0° (0 0 2), 29.7° (2 2 0), 34.9° (3 1 1) and 56.2° (5 1 1). The new peaks at 2h = 29.7° (2 2 0), 34.9° (3 1 1) and 56.2° (5 1 1) matching the PDF#74-2401 well can be
Figs. 4 and 5 give typical SEM and TEM images for PANI, CNTs, Mn0.6Zn0.4Fe2O4-CNTs as well as the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites, respectively. The electron diffraction pattern of Mn0.6Zn0.4Fe2O4 particles in the nanocomposites has been provided in Fig. 5(d). In Figs. 4(a) and 5(a), we can find that PANI nanolayers tend to stack unorderly with each other. From Figs. 4(b) and 5(b), the micro-tubular structure of CNTs can be obviously observed. The average diameter of CNTs is about 25 nm. As we all known, the high specific surface area of CNTs provides activated points which tend to attract Mn0.6Zn0.4Fe2O4 through r–p conjugated
Fig. 4. SEM images of (a) PANI, (b) CNTs, (c) Mn0.6Zn0.4Fe2O4-CNTs and (d) Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites.
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153
151
Fig. 5. TEM images of (a) PANI, (b) CNTs treated by nitric acid, (c) Mn0.6Zn0.4Fe2O4-CNTs and (d) Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites.
interactions. The CNTs also strengthen the conductivity of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites due to their interesting electrical properties. In Figs. 4(c) and 5(c), Mn0.6Zn0.4Fe2O4 particles are formed onto the surface of CNTs through r–p conjugated interactions. This indicates that Mn0.6Zn0.4Fe2O4-CNTs powders have been synthesized successfully. From Figs. 4(d) and 5(d), we can find that Mn0.6Zn0.4Fe2O4 and CNTs are covered by PANI nanolayers through r–p and p–p conjugated interactions in the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. The various components are marked out in Fig. 5(d). These results are in accordance with the FTIR, XRD and SEM analysis.
CNTs have good conductivity due to carbocyclic conjugated system. However, with the increasing of m(Mn0.6Zn0.4Fe2O4-CNTs)/ m(An), the conductivity of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites gradually decreases. There may be two reasons for that. One reason is that the insulating behavior of Mn0.6Zn0.4Fe2O4 particles onto the surface of CNTs hinders the charge transfer. The other is that the generation of stable r–p bond between PANI and Mn0.6Zn0.4Fe2O4 particles results in the decrease of conjugated p electron density of the PANI in the final composites. When m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) is 0.05, the conductivity of the nanocomposites reaches 3.268 S/m.
3.5. Conductivity analysis The conductivity values of PANI and the Mn0.6Zn0.4Fe2O4-CNTs/ PANI nanocomposites with different m(Mn0.6Zn0.4Fe2O4-CNTs)/ m(An) of 0.05, 0.10 and 0.15 are listed in Table 2. The conductivity of PANI nanolayers achieves 107.2 S/m due to the presence of a conjugated p electron system in their structure. As we all known,
Table 2 The conductivity of PANI and the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with different m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05, 0.10 and 0.15. Sample
Conductivity (S/m)
PANI Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05 Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.10 Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.15
107.2 3.268 0.957 0.649
Fig. 6. Magnetization hysteretic loops for the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with different m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of (a) 0.05, (b) 0.10, (c) 0.15, and (d) Mn0.6Zn0.4Fe2O4-CNTs.
152
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153
Table 3 The magnetic parameters of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with different m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05, 0.10, 0.15, and (d) Mn0.6Zn0.4Fe2O4-CNTs. Sample
Ms (emu/g)
Mr (emu/g)
Hc (Oe)
Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05 Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.10 Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.15 Mn0.6Zn0.4Fe2O4-CNTs
7.53 11.75 15.44 24.07
1.90 2.98 5.06 6.47
201.31 254.99 308.68 362.36
3.6. Magnetic property Fig. 6 shows the hysteresis loops of the Mn0.6Zn0.4Fe2O4-CNTs/ PANI nanocomposites with different m(Mn0.6Zn0.4Fe2O4-CNTs)/ m(An) of 0.05, 0.10, 0.15, and the Mn0.6Zn0.4Fe2O4-CNTs. The magnetic parameters of them determined by the hysteresis loops are given in Table 3. The Mn0.6Zn0.4Fe2O4-CNTs powders exhibit ferromagnetic properties with a saturated magnetization (Ms) of 24.07 emu/g and a coercive force (Hc) of 362.36 Oe, respectively. According to the equation Ms = ums, Ms is related to the volume fraction of the magnetic particles (u) and the saturation moment of a single particle (ms) [26]. The Ms, Mr (residual magnetization) and Hc of the final composites decrease with the decreasing of m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An). It is due to the non-magnetic PANI nanolayers contributions to the total magnetization, resulting in a decrease in Ms and Mr. And in the polymerization process, PANI may cover Mn0.6Zn0.4Fe2O4 and CNTs surface defects, such as meshes and cracks, leading to a lower coercivity. When m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) is 0.15, the Ms, Mr and Hc achieves 15.44 emu/g, 5.06 emu/g and 308.68 Oe. However, when m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) is 0.05, the Ms, Mr and Hc reaches 7.53 emu/g, 1.90 emu/g and 201.31 Oe, respectively. The Mn0.6Zn0.4Fe2O4-CNTs composites have been added into PANI giving the obvious magnetic behavior for the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. And the composites have also remained relatively good conductivity. 4. Conclusion The Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites are obtained by the method through the hydrothermal synthesis coupled with in situ polymerization. FTIR and XRD patterns reveal that there are interactions among Mn0.6Zn0.4Fe2O4 particles, CNTs and PANI nanolayers. The microstructure of composites can be seen clearly in the SEM and TEM images. Mn0.6Zn0.4Fe2O4 is formed onto the surface of the CNTs. And PANI nanolayers are coated onto the surface of Mn0.6Zn0.4Fe2O4 and CNTs. Conductivity tests illustrate that the composite has the performance of semiconductor. The results of VSM indicate that the composite exhibits a clear hysteretic behavior. And the value of m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) influences the magnetic parameters such as Ms, Mr and Hc of the final composites. When the value of m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) is at 0.15, the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites possess the best magnetic parameter and the strongest hysteretic loss ability. This work may have supplied important dates in the study of electromagnetic composites. We fully believe that the more optimal electromagnetic materials combining higher conductivity and stronger saturated magnetization can be obtained in a short time. Acknowledgements This work was financially supported by the National Natural Science Foundation of China (Nos. 20904019 and 51273089), the Aviation Science Fund of China (Nos. 2011ZF56015 and 2013ZF56025), Natural Science Foundation of Jiangxi Province
(No. 20132BAB203018), Key Laboratory of Photochemical Conversion and Optoelectronic Materials, TIPC, CSA (Nos. PCOM201228 and PCOM201130), Jiangxi Province Education Department of Science and Technology Project (No. GJJ13491), Jiangxi Province Youth Scientists Cultivating Object Program (No. 20112BCB23017) and Key Laboratory of Jiangxi Province for Persistant Pollutants, Resources Recycle, Nanchang Hangkong University (No. ST201222007) and the Postgraduate Innovation Fund of Jiangxi Province (No. YC2013-S212).
References [1] Pedro GR. Hybrid organic–inorganic materials-in search of synergic activity. Adv Mater 2001;13(3):163. [2] Kawaguchi H. Functional polymer microspheres. Prog Polym Sci 2000;25:1171. [3] Kalinina O, Kumacheva F. A ‘core-shell’ approach to producing 3d polymer nanocomposites. Macromolecules 1999;32:4122. [4] Marchessault RH, Rioux P, Raymond L. Magnetic cellulose fibres and paper: preparation, processing and properties. Polymer 1992;33:4024. [5] Xie Y, Hong XW, Yu CL, Li MJ, Huang Y, Gao YH, et al. Preparation and magnetic properties of poly(3-octyl-thiophene)/BaFe11.92(LaNd)0.04O19-titanium dioxide/multiwalled carbon nanotubes nanocomposites. Compos Sci Techonol 2013;8:77. [6] Dhanabalan A, Talwar SS, Contractor AQ, Kumar NP, Narang SN, Major SS, et al. Polyaniline–Cds composite films obtained from polyaniline–cadmium arachidate multilayers. J Mater Sci Lett 1999;18:603. [7] Ziolo RF, Fiannelis EP, Weistein BA, ÓHoro MP, Ganguly BN, Mehrotra V, et al. Matrix-mediated synthesis of nanocrystalline c-Fe2O3: a new optically transparent magnetic material. Science 1992;257:219. [8] Xie Y, Hong XW, Gao YH, Li MJ, Liu JM, Wang J, et al. Synthesis and characterization of La/Nd-doped barium-ferrite/polypyrrole nanocomposites. Synth Met 2012;162(7–8):677. [9] Xie Y, Hong XW, Wang XY, Zhao J, Gao YH, Ling Y, et al. Preparation and electromagnetic properties of La-doped barium-ferrite/polythiophene composites. Synth Met 2012;162:1643. [10] Zhao J, Xie Y, Yu CL, Le ZG, Zhong R, Qin YC, et al. Preparation and characterization of the graphene carbon nanotube/CoFe2O4/polyaniline composite with reticular branch structures. Mater Chem Phys 2013;142:395. [11] Xia HS, Wang Q. Ultrasonic irradiation: a novel approach to prepare conductive polyaniline/nanocrystalline titanium oxide composites. Chem Mater 2002;14:2158. [12] Li LC, Jiang J, Xu F. Novel polyaniline-LiNi0.5La0.02Fe1.98O4 nanocomposites prepared via an in situ polymerization. Eur Polym 2006;42:2221. [13] Jiang J, Li LC, Xu F. Polyaniline-LiNi ferrite core-shell composite: preparation, characterization and properties. Mater Sci Eng A 2007;456:300. [14] Jiang J, Li LC, Zhu ML. Polyaniline/magnetic ferrite nanocomposites obtained by in situ polymerization. React Funct Polym 2008;68:57. [15] Jiang J, Li LC, Xu F. In situ synthesis and characterization of LiNi0.5La0.08Fe1.92O4-polyaniline core-shell nanocomposites. J Phys Chem Solids 2007;68:1656. [16] Ding HJ, Liu XM, Wan MX, Fu SY. Electromagnetic functionalized cage-like polyaniline composite nanostructures. J Phys Chem B 2008;112:9289. [17] Salvetat JP, Kulik A, Bonard JM, Briggs GAD, Stockli T, Metenier K, et al. Elastic modulus of ordered and disordered multiwalled carbon nanotubes. Adv Mater 1999;11(2):161. [18] Odom TW, Huang JL, Kim P, Lieber CM. Atomic structure and electronic properties of single-walled carbon nanotubes. Nature 1998;391:62. [19] Wildoer JWG, Venema LC, Rinzler AG, Smalley RE, Dekker C. Electronic structure of atomically resolved carbon nanotubes. Nature 1998;391:59. [20] Zhao DX, Li QL, Ye Y, Zhang CR. Synthesis and characterization of carbon nanotubes decorated with strontium ferrite nanoparticles. Synth Met 2010;160:866. [21] Li QL, Ye Y, Zhao DX, Zhang W, Zhang Y. Preparation and characterization of CNTs-SrFe12O19 composites. J Alloys Compd 2011;509:1777. [22] Quilard S, Louarn G, Lefrant S, MacDiarmid AG. Vibrational analysis of polyaniline: a comparative study of leucoemeraldine, emeraldine, and pernigraniline bases. Phys Rev B 1994;50:12496. [23] Moon YB, Cao Y, Smith P, Heeger A. X-ray diffraction of polyaniline. J Polym Commum 1989;30:196.
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153 [24] Pouget JP, Jozefowicz ME, Epstein AJ, Tang X, MacDiarmid AG. X-ray structure of polyaniline. Macromolecules 1991;24:779. [25] Zhou C, Fang QQ, Yan FL. Enhanced microwave absorption in ZnO/carbonyl iron composites by coating dielectric material. J Magn Magn Mater 2012;324:1720.
153
[26] Sauzedde F, Esmïssari A, Pichot C. Hydrophilic magnetic polymer latexes. 1. Adsorption of magnetic iron oxide nanoparticles onto various cationic latexes. Colloid Polym Sci 1999;277:846.
Contents lists available at ScienceDirect
Composites Science and Technology journal homepage: www.elsevier.com/locate/compscitech
Preparation of magnetic-conductive Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites through hydrothermal synthesis coupled with in situ polymerization Jie Zhao a, Yu Xie a,⇑, Mingjun Li a, Fangcheng Xu b, Zhanggao Le c,⇑, Yuancheng Qin a, Dan Zhou a, Zhenguo Wang d, Hai Xu a, Jianfei Pan a, Yun Ling a a
Department of Materials Chemistry, Nanchang Hangkong University, Nanchang 330063, PR China College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, PR China c Department of Applied Chemistry, East China Institute of Technology, Fuzhou 344000, PR China d Key Laboratory of Green Chemistry and Technology of Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, PR China b
a r t i c l e
i n f o
Article history: Received 25 February 2014 Received in revised form 11 May 2014 Accepted 13 May 2014 Available online 23 May 2014 Keywords: A. Functional composites A. Nanocomposites A. Polymer–matrix composites B. Magnetic properties B. Electrical properties
a b s t r a c t A facile chemical method through hydrothermal synthesis coupled with in situ polymerization to prepare the Mn0.6Zn0.4Fe2O4-carbon nanotubes (CNTs)/polyaniline (PANI) nanocomposites has been reported in this paper. The structure of samples has been characterized by the Fourier transform infrared and Xray diffraction. The shape and size of samples have been observed by the scanning electron microscopy and transmission electron microscopy. The conductive properties of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites have been tested by a four-probe conductivity tester at room temperature. And the magnetic properties are measured by a vibrating sample magnetometer. When the mass ratio of the Mn0.6Zn0.4Fe2O4-CNTs to aniline (m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An)) is 0.15, the Ms, Mr and Hc achieves 15.44 emu/g, 5.06 emu/g and 308.68 Oe, respectively. At the same time the probable formation mechanism of nanocomposites is also investigated based on the experimental results. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Researches on the inorganic–organic conductive-magnetic nanocomposites have attracted more and more attentions [1–8]. Combining magnetic particles and conductive polymers is a workable route to prepare the conductive-magnetic nanocomposites [9,10]. Due to the unique electrical, easy preparation, excellent environment stability, optical and optoelectrical characteristics, the polyaniline (PANI) has become one of the most popular conductive polymers [11]. Li’s group has prepared a series of the magnetic particles-PANI composites using an in situ polymerization [12–15]. Wan et al. has synthesized a novel cage-like and electromagnetic functional PANI/CoFe2O4 nanocomposites by a self-assembly process. The cage-like composites possess high conductivity (rmax5.2 S/cm) and typical ferromagnetic behaviors [16]. In addition, CNTs have been characterized by the nanometric dimension, high aspect ratio, chemical stability, high Young’s
⇑ Corresponding authors. Tel./fax: +86 (791) 83953373 (Y. Xie). E-mail addresses: [email protected] (Y. Xie), [email protected] (Z. Le). http://dx.doi.org/10.1016/j.compscitech.2014.05.023 0266-3538/Ó 2014 Elsevier Ltd. All rights reserved.
modulus and interesting electrical properties, especially large permittivity [17–19]. Zhao et al. using in situ sol–gel method has connected the magnetic nanoparticles onto the surface of CNTs preparing the CNTs-magnetic nanoparticles. The size of magnetic nanoparticles is at the nanometer level [20,21]. Therefore, a general approach has been proposed as follows. Firstly, magnetic particles are formed and absorbed onto the surface of CNTs through the hydrothermal synthesis reaction. Then aniline (An) monomers will get together forming PANI onto the surface of the magnetic particles coated CNTs through in situ polymerization. In this paper, we have coupled with hydrothermal synthesis and in situ polymerization to successfully prepare the magneticconductive Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. The structure, morphology, conductive properties and magnetic properties of the composites have also been characterized. This study may have provided a general approach to synthesize the ternary composites of the MXNYFe2O4 (M, N = Mn, Zn, Li, Ni, Cr, La, Ba, et al.; X + Y = 1)-CNTs/conductive polymers. At the same time, it also contributes to investigate and reveals the exchange interactions among magnetic particles, CNTs and conductive polymers, as well as the relations of the conductive performances and the magnetic properties.
148
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153
solution stirring for 12 h. After that, the suspension was filtered and the residue was washed with absolute ethanol and deionized water, respectively. The obtained product was dried under vacuum at 60 °C for 10 h.
2. Experiment 2.1. Materials In this study, aniline (C6H5NH2, An, AR, 99.5%) and dodecylbenzene sulfonic acid (C18H30O3S, DBSA, 90%) were purchased from Aladdin Chemistry Co. Ltd. CNTs (Multiwalled; OD 20–30 nm; Length 10–30 lm; Purity >95% (Raman); Ash <0.5 wt.%; SSA >200 m2/g; EC >102 S/cm) were purchased from Beijing DK Nano Technology Co. Ltd. Other chemicals were analytical reagent. 2.2. Synthesis of PANI 1.0 g An was added into 20 mL 1 mol/L HCl stirring for 1 h at 5 °C. 10 mL 1 mol/L (NH4)2S2O8 was slowly dropped into the above
2.3. Preparation of the Mn0.6Zn0.4Fe2O4-CNTs CNTs were treated by 14.5 mol/L nitric acid at 60 °C for 30 min. 2.0 g treated CNTs were added into 50 mL deionized water under ultrasonic dispersing for 1 h. Then, 4.0 g DBSA was added into the above solution under ultrasonic dispersing for 2.5 h. The suspension was filtered, and the residue was washed with deionized water until the pH of the filtrate to 7. The product was dried under vacuum at 50 °C for 24 h. After that, the modified CNTs by DBSA were obtained. 0.20 g MnSO4H2O, 0.24 g Zn(NO3)26H2O and
Table 1 The stoichiometric amounts of every material used to prepare the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposite.
Mn0.6Zn0.4Fe2O4-CNTs/PANI with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05 Mn0.6Zn0.4Fe2O4-CNTs/PANI with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.10 Mn0.6Zn0.4Fe2O4-CNTs/PANI with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.15
Mn0.6Zn0.4Fe2O4-CNTs (g)
Aniline (g)
(NH4)2S2O8 (mL)
0.05 0.10 0.15
1.0 1.0 1.0
10 10 10
Fig. 1. The proposed preparation scheme of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites.
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153
149
3. Results and discussion 3.1. Proposed preparation scheme of the nanocomposites
Fig. 2. FTIR spectra of (a) PANI, (b) CNTs, (c) Mn0.6Zn0.4Fe2O4-CNTs and (d) Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites.
1.62 g Fe(NO3)39H2O were dissolved into 50 mL deionized water. Then, 1.0 g modified CNTs were added into the above solution under ultrasonic dispersing for 0.5 h. 10 mol/L NaOH was slowly dropped into the mixed solution within 0.5 h until pH > 8. And then, the mixed solution was layered. The supernatant was removed, and the precipitate was transferred into reaction kettle at 180 °C for 5 h. After completion of the reaction, the system was cooled to room temperature, and the solution was filtered. The residue was washed with absolute ethanol and deionized water, respectively. Finally, the products were dried under vacuum at 60 °C for 24 h. 2.4. Preparation of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites 1.0 g An and 0.05 g the Mn0.6Zn0.4Fe2O4-CNTs were added into 35 mL 0.1 mol/L HCl stirring for 30 min forming solution A. 10 mL 1 mol/L (NH4)2S2O8 was added into 15 mL 0.1 mol/L HCl forming solution B. Solution B was slowly added into solution A stirring for 12 h at 5 °C. After that, the mixed solution was filtered, and filtered matter was washed with absolute ethanol and deionized water, respectively. The product was dried under vacuum at 60 °C for 24 h. Changing the mass ratio of the Mn0.6Zn0.4Fe2O4CNTs to An and according with the above method, the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites were obtained with different m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05, 0.10 and 0.15, respectively. The stoichiometric amounts of every material used to prepare the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites have been listed in Table 1.
Fig. 1 illustrated a simple preparation process of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. CNTs were oxidized by nitric acid and DBSA, respectively. After that, there were a large number of -COO-, -OH and sulfonic acid groups onto the surface of CNTs. Then, Fe3+, Mn2+ and Zn2+ ions were self-adsorbed by the ACOO and sulfonic acid groups. The Mn0.6Zn0.4Fe2O4 was formed onto the surface of CNTs at 180 °C for 5 h. Immediately, a large number of Cl was adsorbed onto the surface of Mn0.6Zn0.4Fe2O4. And then, the An molecules were adsorbed onto the surface of the Cl and CNTs through electrostatic attraction and p–p interactions, respectively. Finally, under (NH4)2S2O8 initiator, the in situ polymerization reaction of An was carried on. The Mn0.6Zn0.4Fe2O4-CNTs/ PANI nanocomposites had been successfully synthesized, and the characterization discussed below.
3.2. FTIR analysis Fig. 2 shows the FTIR spectra of PANI, CNTs, Mn0.6Zn0.4Fe2O4CNTs and the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. In Fig. 2(a), the characteristic peaks of PANI are at 1559, 1489, 1292, 1104, 793, 613 and 502 cm 1 with slightly movement compared with the literature [16]. The peaks at 1559 and 1489 cm 1 are attributed to the characteristic C@C stretching of the quiniod and benzenoid rings. 1292 cm 1 is assigned to CAN stretching of secondary aromatic amine. The broad peak at 1104 cm 1 which is described by MacDiarmid et al. as the ‘electronic-like band’ is assigned to the vibration mode of N = Q = N. It indicates that PANI has been synthesized successfully in our samples [22]. 793, 613 and 502 cm 1 could be assigned to the out-of-plane rocking vibration of @CAH group in the 1,4-disubstituted benzene ring. And the peak at 3448 cm 1 is related to water molecules. From Fig. 2(b), the characteristic peak of CNTs is weak at 1637 cm 1 due to C@C symmetrical stretching vibration. The characteristic absorption peaks of the Mn0.6Zn0.4Fe2O4-CNTs are at 1578, 1385, 1125, 1062, 605 and 472 cm 1 in Fig. 2(c). Compared with Fig. 2(b), after modification by ACOO , AOH and DBSA, obvious peaks at 1578, 1385, 1125 and 1062 cm 1 can be found. The stronger 1578 cm 1 peak may be due to C@C stretching of benzenoid ring of DBSA on the surface of CNTs. 1385 cm 1 is attributed to C@O stretching vibration, and the peak at 1125 cm 1 can be assigned to CAC stretching vibration. Peak at 1062 cm 1 is related to AOAH group. The new peaks at 605 and 472 cm 1 are attributed to Fe(Mn or Zn)AO stretching
2.5. Characterization Fourier transform infrared (FTIR) spectra was obtained using Nicolet 5700 FTIR with KBr method. X-ray diffraction (XRD) patterns of the samples were characterized by using a philpspw3040/60 diffractometer with Cu Ka radiation (k = 0.15418 nm). The morphologies and the microstructure of the synthesized samples were observed by a scanning electron microscopy (SEM, Nova NanoSEM450) and a transmission electron microscope (TEM, JEOL JEM2010), respectively. The electrical conductivities were carried out on a four-probe resistivity instrument (SDY-4) at room temperature using pressed pellets of sample’s powder with the thickness of about 1 mm and diameter of 20 mm under 70 MPa. A Lakeshore 7404 vibrating sample magnetometer was used to measure the magnetization of the samples in applied magnetic fields over the range of 10 to +10 kOe at room temperature.
Fig. 3. XRD patterns of (a) PANI, (b) CNTs, (c) Mn0.6Zn0.4Fe2O4-CNTs and (d) Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites.
150
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153
vibration. This indicates that Mn0.6Zn0.4Fe2O4 has been formed onto the surface of CNTs through r–p conjugated interactions. In Fig. 2(d), the characteristic absorption peaks of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites are at 1574, 1493, 1298, 1139, 818, 694 and 508 cm 1. The peaks at 1574, 1493, 1298, 1139, 818 and 694 cm 1 can be assigned to characteristic peaks of PANI with slightly blue-shift compared with Fig. 2(a). This indicates that there are some r–p and p–p interactions among Mn0.6Zn0.4Fe2O4, CNTs and PANI. And 508 cm 1 in Fig. 2(d) can be attributed to Mn0.6Zn0.4Fe2O4 characteristic peak. Therefore, the Mn0.6Zn0.4 Fe2O4-CNTs/PANI nanocomposites have been synthesized successfully.
assigned to the Mn0.6Zn0.4Fe2O4 characteristic peaks. This indicates that there are interactions between Mn0.6Zn0.4Fe2O4 and CNTs. In Fig. 3(d), the characteristic peaks of the Mn0.6Zn0.4Fe2O4-CNTs/ PANI nanocomposites are at 2h = 15.4°, 19.6° and 25.7°. However, the characteristic peaks of Mn0.6Zn0.4Fe2O4 and CNTs are disappeared due to the small mass ratio of m(Mn0.6Zn0.4Fe2O4-CNTs) to m(An). The diffraction peaks of Mn0.6Zn0.4Fe2O4 and CNTs have been covered by the PANI diffraction peaks in the Mn0.6Zn0.4Fe2O4CNTs/PANI nanocomposites. This indicates that Mn0.6Zn0.4Fe2O4 and CNTs are wrapped in the PANI through r–p and p–p interactions. Therefore, the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites have been synthesized successfully in our paper and the morphology analysis discussed below.
3.3. XRD analysis 3.4. Morphology analysis Fig. 3 shows the XRD patterns of PANI, CNTs, the Mn0.6Zn0.4 Fe2O4-CNTs and the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. In Fig. 3(a), the PANI characteristic diffraction peaks are at 2h = 15.3°, 20.4° and 25.4° with slightly different from the reported [16]. 2h at 20.4° and 25.4° can be assigned as planes perpendicular and parallel to the polymer chain, [23,24] respectively. In Fig. 3(b), the CNTs characteristic peak is at 2h = 26.1° can be ascribed to the (0 0 2) reflection [25]. From Fig. 3(c), the characteristic peaks of the Mn0.6Zn0.4Fe2O4-CNTs are at 2h = 26.0° (0 0 2), 29.7° (2 2 0), 34.9° (3 1 1) and 56.2° (5 1 1). The new peaks at 2h = 29.7° (2 2 0), 34.9° (3 1 1) and 56.2° (5 1 1) matching the PDF#74-2401 well can be
Figs. 4 and 5 give typical SEM and TEM images for PANI, CNTs, Mn0.6Zn0.4Fe2O4-CNTs as well as the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites, respectively. The electron diffraction pattern of Mn0.6Zn0.4Fe2O4 particles in the nanocomposites has been provided in Fig. 5(d). In Figs. 4(a) and 5(a), we can find that PANI nanolayers tend to stack unorderly with each other. From Figs. 4(b) and 5(b), the micro-tubular structure of CNTs can be obviously observed. The average diameter of CNTs is about 25 nm. As we all known, the high specific surface area of CNTs provides activated points which tend to attract Mn0.6Zn0.4Fe2O4 through r–p conjugated
Fig. 4. SEM images of (a) PANI, (b) CNTs, (c) Mn0.6Zn0.4Fe2O4-CNTs and (d) Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites.
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153
151
Fig. 5. TEM images of (a) PANI, (b) CNTs treated by nitric acid, (c) Mn0.6Zn0.4Fe2O4-CNTs and (d) Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites.
interactions. The CNTs also strengthen the conductivity of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites due to their interesting electrical properties. In Figs. 4(c) and 5(c), Mn0.6Zn0.4Fe2O4 particles are formed onto the surface of CNTs through r–p conjugated interactions. This indicates that Mn0.6Zn0.4Fe2O4-CNTs powders have been synthesized successfully. From Figs. 4(d) and 5(d), we can find that Mn0.6Zn0.4Fe2O4 and CNTs are covered by PANI nanolayers through r–p and p–p conjugated interactions in the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. The various components are marked out in Fig. 5(d). These results are in accordance with the FTIR, XRD and SEM analysis.
CNTs have good conductivity due to carbocyclic conjugated system. However, with the increasing of m(Mn0.6Zn0.4Fe2O4-CNTs)/ m(An), the conductivity of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites gradually decreases. There may be two reasons for that. One reason is that the insulating behavior of Mn0.6Zn0.4Fe2O4 particles onto the surface of CNTs hinders the charge transfer. The other is that the generation of stable r–p bond between PANI and Mn0.6Zn0.4Fe2O4 particles results in the decrease of conjugated p electron density of the PANI in the final composites. When m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) is 0.05, the conductivity of the nanocomposites reaches 3.268 S/m.
3.5. Conductivity analysis The conductivity values of PANI and the Mn0.6Zn0.4Fe2O4-CNTs/ PANI nanocomposites with different m(Mn0.6Zn0.4Fe2O4-CNTs)/ m(An) of 0.05, 0.10 and 0.15 are listed in Table 2. The conductivity of PANI nanolayers achieves 107.2 S/m due to the presence of a conjugated p electron system in their structure. As we all known,
Table 2 The conductivity of PANI and the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with different m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05, 0.10 and 0.15. Sample
Conductivity (S/m)
PANI Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05 Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.10 Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.15
107.2 3.268 0.957 0.649
Fig. 6. Magnetization hysteretic loops for the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with different m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of (a) 0.05, (b) 0.10, (c) 0.15, and (d) Mn0.6Zn0.4Fe2O4-CNTs.
152
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153
Table 3 The magnetic parameters of the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with different m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05, 0.10, 0.15, and (d) Mn0.6Zn0.4Fe2O4-CNTs. Sample
Ms (emu/g)
Mr (emu/g)
Hc (Oe)
Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.05 Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.10 Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites with m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) of 0.15 Mn0.6Zn0.4Fe2O4-CNTs
7.53 11.75 15.44 24.07
1.90 2.98 5.06 6.47
201.31 254.99 308.68 362.36
3.6. Magnetic property Fig. 6 shows the hysteresis loops of the Mn0.6Zn0.4Fe2O4-CNTs/ PANI nanocomposites with different m(Mn0.6Zn0.4Fe2O4-CNTs)/ m(An) of 0.05, 0.10, 0.15, and the Mn0.6Zn0.4Fe2O4-CNTs. The magnetic parameters of them determined by the hysteresis loops are given in Table 3. The Mn0.6Zn0.4Fe2O4-CNTs powders exhibit ferromagnetic properties with a saturated magnetization (Ms) of 24.07 emu/g and a coercive force (Hc) of 362.36 Oe, respectively. According to the equation Ms = ums, Ms is related to the volume fraction of the magnetic particles (u) and the saturation moment of a single particle (ms) [26]. The Ms, Mr (residual magnetization) and Hc of the final composites decrease with the decreasing of m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An). It is due to the non-magnetic PANI nanolayers contributions to the total magnetization, resulting in a decrease in Ms and Mr. And in the polymerization process, PANI may cover Mn0.6Zn0.4Fe2O4 and CNTs surface defects, such as meshes and cracks, leading to a lower coercivity. When m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) is 0.15, the Ms, Mr and Hc achieves 15.44 emu/g, 5.06 emu/g and 308.68 Oe. However, when m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) is 0.05, the Ms, Mr and Hc reaches 7.53 emu/g, 1.90 emu/g and 201.31 Oe, respectively. The Mn0.6Zn0.4Fe2O4-CNTs composites have been added into PANI giving the obvious magnetic behavior for the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites. And the composites have also remained relatively good conductivity. 4. Conclusion The Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites are obtained by the method through the hydrothermal synthesis coupled with in situ polymerization. FTIR and XRD patterns reveal that there are interactions among Mn0.6Zn0.4Fe2O4 particles, CNTs and PANI nanolayers. The microstructure of composites can be seen clearly in the SEM and TEM images. Mn0.6Zn0.4Fe2O4 is formed onto the surface of the CNTs. And PANI nanolayers are coated onto the surface of Mn0.6Zn0.4Fe2O4 and CNTs. Conductivity tests illustrate that the composite has the performance of semiconductor. The results of VSM indicate that the composite exhibits a clear hysteretic behavior. And the value of m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) influences the magnetic parameters such as Ms, Mr and Hc of the final composites. When the value of m(Mn0.6Zn0.4Fe2O4-CNTs)/m(An) is at 0.15, the Mn0.6Zn0.4Fe2O4-CNTs/PANI nanocomposites possess the best magnetic parameter and the strongest hysteretic loss ability. This work may have supplied important dates in the study of electromagnetic composites. We fully believe that the more optimal electromagnetic materials combining higher conductivity and stronger saturated magnetization can be obtained in a short time. Acknowledgements This work was financially supported by the National Natural Science Foundation of China (Nos. 20904019 and 51273089), the Aviation Science Fund of China (Nos. 2011ZF56015 and 2013ZF56025), Natural Science Foundation of Jiangxi Province
(No. 20132BAB203018), Key Laboratory of Photochemical Conversion and Optoelectronic Materials, TIPC, CSA (Nos. PCOM201228 and PCOM201130), Jiangxi Province Education Department of Science and Technology Project (No. GJJ13491), Jiangxi Province Youth Scientists Cultivating Object Program (No. 20112BCB23017) and Key Laboratory of Jiangxi Province for Persistant Pollutants, Resources Recycle, Nanchang Hangkong University (No. ST201222007) and the Postgraduate Innovation Fund of Jiangxi Province (No. YC2013-S212).
References [1] Pedro GR. Hybrid organic–inorganic materials-in search of synergic activity. Adv Mater 2001;13(3):163. [2] Kawaguchi H. Functional polymer microspheres. Prog Polym Sci 2000;25:1171. [3] Kalinina O, Kumacheva F. A ‘core-shell’ approach to producing 3d polymer nanocomposites. Macromolecules 1999;32:4122. [4] Marchessault RH, Rioux P, Raymond L. Magnetic cellulose fibres and paper: preparation, processing and properties. Polymer 1992;33:4024. [5] Xie Y, Hong XW, Yu CL, Li MJ, Huang Y, Gao YH, et al. Preparation and magnetic properties of poly(3-octyl-thiophene)/BaFe11.92(LaNd)0.04O19-titanium dioxide/multiwalled carbon nanotubes nanocomposites. Compos Sci Techonol 2013;8:77. [6] Dhanabalan A, Talwar SS, Contractor AQ, Kumar NP, Narang SN, Major SS, et al. Polyaniline–Cds composite films obtained from polyaniline–cadmium arachidate multilayers. J Mater Sci Lett 1999;18:603. [7] Ziolo RF, Fiannelis EP, Weistein BA, ÓHoro MP, Ganguly BN, Mehrotra V, et al. Matrix-mediated synthesis of nanocrystalline c-Fe2O3: a new optically transparent magnetic material. Science 1992;257:219. [8] Xie Y, Hong XW, Gao YH, Li MJ, Liu JM, Wang J, et al. Synthesis and characterization of La/Nd-doped barium-ferrite/polypyrrole nanocomposites. Synth Met 2012;162(7–8):677. [9] Xie Y, Hong XW, Wang XY, Zhao J, Gao YH, Ling Y, et al. Preparation and electromagnetic properties of La-doped barium-ferrite/polythiophene composites. Synth Met 2012;162:1643. [10] Zhao J, Xie Y, Yu CL, Le ZG, Zhong R, Qin YC, et al. Preparation and characterization of the graphene carbon nanotube/CoFe2O4/polyaniline composite with reticular branch structures. Mater Chem Phys 2013;142:395. [11] Xia HS, Wang Q. Ultrasonic irradiation: a novel approach to prepare conductive polyaniline/nanocrystalline titanium oxide composites. Chem Mater 2002;14:2158. [12] Li LC, Jiang J, Xu F. Novel polyaniline-LiNi0.5La0.02Fe1.98O4 nanocomposites prepared via an in situ polymerization. Eur Polym 2006;42:2221. [13] Jiang J, Li LC, Xu F. Polyaniline-LiNi ferrite core-shell composite: preparation, characterization and properties. Mater Sci Eng A 2007;456:300. [14] Jiang J, Li LC, Zhu ML. Polyaniline/magnetic ferrite nanocomposites obtained by in situ polymerization. React Funct Polym 2008;68:57. [15] Jiang J, Li LC, Xu F. In situ synthesis and characterization of LiNi0.5La0.08Fe1.92O4-polyaniline core-shell nanocomposites. J Phys Chem Solids 2007;68:1656. [16] Ding HJ, Liu XM, Wan MX, Fu SY. Electromagnetic functionalized cage-like polyaniline composite nanostructures. J Phys Chem B 2008;112:9289. [17] Salvetat JP, Kulik A, Bonard JM, Briggs GAD, Stockli T, Metenier K, et al. Elastic modulus of ordered and disordered multiwalled carbon nanotubes. Adv Mater 1999;11(2):161. [18] Odom TW, Huang JL, Kim P, Lieber CM. Atomic structure and electronic properties of single-walled carbon nanotubes. Nature 1998;391:62. [19] Wildoer JWG, Venema LC, Rinzler AG, Smalley RE, Dekker C. Electronic structure of atomically resolved carbon nanotubes. Nature 1998;391:59. [20] Zhao DX, Li QL, Ye Y, Zhang CR. Synthesis and characterization of carbon nanotubes decorated with strontium ferrite nanoparticles. Synth Met 2010;160:866. [21] Li QL, Ye Y, Zhao DX, Zhang W, Zhang Y. Preparation and characterization of CNTs-SrFe12O19 composites. J Alloys Compd 2011;509:1777. [22] Quilard S, Louarn G, Lefrant S, MacDiarmid AG. Vibrational analysis of polyaniline: a comparative study of leucoemeraldine, emeraldine, and pernigraniline bases. Phys Rev B 1994;50:12496. [23] Moon YB, Cao Y, Smith P, Heeger A. X-ray diffraction of polyaniline. J Polym Commum 1989;30:196.
J. Zhao et al. / Composites Science and Technology 99 (2014) 147–153 [24] Pouget JP, Jozefowicz ME, Epstein AJ, Tang X, MacDiarmid AG. X-ray structure of polyaniline. Macromolecules 1991;24:779. [25] Zhou C, Fang QQ, Yan FL. Enhanced microwave absorption in ZnO/carbonyl iron composites by coating dielectric material. J Magn Magn Mater 2012;324:1720.
153
[26] Sauzedde F, Esmïssari A, Pichot C. Hydrophilic magnetic polymer latexes. 1. Adsorption of magnetic iron oxide nanoparticles onto various cationic latexes. Colloid Polym Sci 1999;277:846.