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Self-assembly of cross-linked carbon nanotube films for improvement on mechanical properties and conductivity
Materials Letters 231 (2018) 190–193
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Self-assembly of cross-linked carbon nanotube films for improvement on mechanical properties and conductivity Qianshan Xia a, Zhichun Zhang a, Yanju Liu b, Jinsong Leng a,⇑ a b
Center for Composite Materials and Structures, No. 2 YiKuang Street, Science Park of Harbin Institute of Technology (HIT), Harbin 150080, PR China Department of Aerospace Science and Mechanics, No. 92 West DaZhi Street, Harbin Institute of Technology (HIT), Harbin 150001, PR China
a r t i c l e
i n f o
Article history: Received 18 March 2018 Received in revised form 20 June 2018 Accepted 10 August 2018 Available online 11 August 2018 Keywords: Carbon nanotubes Cross-linking Thin films
a b s t r a c t A facile strategy for cross-linked carbon nanotube film (CL-CNF) was carried out via self-assembly of carbon nanotubes (CNTs), which was achieved based on esterification and acylation reactions of functional CNTs respectively. Comparing with uncross-linked carbon nanotube film, this strategy could benefit for enhancing mechanical properties of CNF through altering the inter-tube interaction from weaker Van der Waals force to stronger chemical bonding, but not lost its conductivity. The tensile strength and Young’s modulus of CL-CNF were remarkably enhanced, which were higher 263% and 190% than uncross-linked CNF. Meanwhile, conductivity of CNF after cross-linking increased to 210%. In this paper, the forming ester and acylation bonding in CNT network led to differences of their morphology that were observed on nanoscale. This method promoted CL-CNF as a promising material to be applied in water treatment and self-heating materials. Ó 2018 Published by Elsevier B.V.
1. Introduction Owing to their low density and excellent electrical property, carbon materials are obtained more attention, including carbon nanotubes (CNTs) [1] and graphene [2], etc. Since CNT was first found in 1991 [3], CNT and its composites have been widely studied. As a macro-material of CNT, carbon nanotube film (CNF) that is generally manufactured via vacuum based and pressurized filtration method, has potential applications in self-heating [4] and water treatment [5–7] materials, etc. However, friability of CNF restricts its application seriously, because the interaction between CNTs in CNF derives from the weaker Van der Waals force. For example, Wang [1] prepared uncross-linked CNF, and stress and strain of uncross-linked CNF were only 22.1 MPa and 1.5%. Construction of CNF/polymer composite was a way to improve mechanical properties of CNF [8]. Although mechanical properties of CNF could be drastically improved via insulating and rigid resin impregnation, its density increasing, conductivity reducing and flexibility losing were inevitably acquired. Another method was preparation of cross-linked CNF (CL-CNF) by introducing some organic cross linkers, such as benzoquinone [9], epibromohydrin [10], etc. It switched intertube interaction from weaker Van der Waals force to stronger
⇑ Corresponding author. E-mail address: [email protected] (J. Leng). https://doi.org/10.1016/j.matlet.2018.08.054 0167-577X/Ó 2018 Published by Elsevier B.V.
chemical bonding. However, introduction of organic cross linker was equivalent to adding insulator between CNTs, and this method would decrease the electrical conductivity of CNF. To obtain the CNF with better mechanical and electrical properties, several CL-CNFs were first prepared by CNTs with carboxyl, hydroxide radical and amidogen via chemical self-assembly. This method was based on esterification and acylation reactions between functional CNTs in different solution systems, respectively. Moreover, mechanism of various reaction conditions influencing on mechanical properties of CL-CNFs was analyzed in this work.
2. Experimental According to previous report [4], the uncross-linked CNF as control group was prepared by single-wall carbon nanotubes (SWCNTs), and its areal density was 2 mg/cm2. Then the SWCNTs containing carboxyl (SWCNTs-COOH) and hydroxy SWCNTs (SWCNTs-OH), and SWCNTs-COOH and SWCNTs containing amidogen (SWCNTs-NH2) with the weight ratio of 1.05: 1, followed the similar preparation process of uncross-linked CNF, to fabricate esterification and acylation CNFs in deionized water (DIW) and dimethylformamide (DMF) solution systems, respectively. Additionally, all the areal density of esterification and acylation CNFs was prepared with 2 mg/cm2. After peeling from the filter membrane, the CNFs prepared in DIW and DMF systems were undergone UV irradiation for 6 h, for obtaining the esterification and
Q. Xia et al. / Materials Letters 231 (2018) 190–193
acylation CL-CNFs. The esterification and acylation CL-CNFs were designated as ECL-CNFs and ACL-CNFs. The thickness of uncrosslinked CNF, ECL-CNFs and ACL-CNFs prepared in DIW and DMF was 30, 27, 29, 27 and 30 um respectively, which was measured by a micrometer.
191
3. Results and discussion Interaction types between CNTs would impact on the morphology of CNFs. Topological differences could be found in partial enlargement images of surface of uncross-linked CNF, ECL-CNFs
Fig. 1. SEM micrographs of surface, pore size distribution and Gaussian distribution curves of a) uncross-linked CNF, b) ECL-CNF prepared in DIW, c) ECL-CNF prepared in DMF, d) ACL-CNF prepared in DIW and e) ACL-CNF prepared in DMF.
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Q. Xia et al. / Materials Letters 231 (2018) 190–193
Fig. 2. a) Mechanical properties and b) conductivity of uncross-linked CNF, ECL-CNF in DIW, ECL-CNF in DMF, ACL-CNF in DIW and ACL-CNF in DMF.
and ACL-CNFs prepared in DIW and DMF, through comparing with Fig. 1(a–e). The surface of uncross-linked CNF was uneven and porous, and its CNT networks were constructed via random distribution of CNTs. Van der Waals force between CNTs led that the CNTs linked with each other and formed an uncross-linked CNF [4]. Compared with uncross-linked CNF, pore diameters and CNT networks of all the CL-CNFs were smaller and denser, due to the strength of the chemical bond stronger than Van der Waals force. Moreover, the peaks of pore size distribution in Fig. 1(a–e) located at 80–90, 10–15, 15–25, 10–20 and 70–80 nm, respectively. Especially, CNT networks of CL-CNFs prepared in DIW presented much denser structures, and the arrangement of CNTs was more regular than the other three CNFs, owing to cross-linked reaction partly occurring in DIW before UV irradiation. The functional groups were usually attached to caps of CNTs. When functional CNTs were diffused in DIW, the caps of CNTs would be connected regularly by ester and acylation bonds. Fig. 2(a) displayed the tensile strength and Young’s modulus of uncross-linked and CL-CNFs. Moreover, the insert photo was a bending esterification CNF, suggesting it was flexible and robust enough to be manipulated as an ordinary paper. Because strength of the chemical bond of CL-CNFs was stronger than Van der Waals force of uncross-linked CNF, and the cross-linking joints between CNT bundles and CNTs increased the overall inter-tube stress transfer abilities. Therefore, the CL-CNFs possessed the higher tensile strength than uncross-linked CNF (17.82 MPa). Compared with five CNFs, the tensile strength of ECL-CNF prepared in DIW was the maximum (64.61 MPa). Moreover, the tensile strength of ECL-CNFs was greater than ACL-CNFs, because strength of ester bond was more powerful than acylation bonding. Before UV irradiation stage, part of CNTs reacted cross-linking in DIW system, and cross-linking degree of CL-CNF synthesized in DIW was higher than DMF. Thus, CL-CNFs prepared in DIW had the higher tensile strength than the ones synthesized in DMF. Likewise, the Young’s modulus of CLCNFs was also higher than uncross-linked CNF (1.11 GPa), thereinto, ECL-CNF prepared in DIW (3.22 GPa) possessed of the maximum of five CNFs. Owing to the stronger inhibiting effect of the ester bond, the Young’s modulus of ECL-CNFs was higher than ACL-CNFs and it meant the ECL-CNFs had higher stiffness. Due to cross-linking degree of CL-CNF prepared in DIW higher than CL-CNF prepared in DMF, CL-CNFs synthesized in DIW hold more powerful resistance to deformation. Thus, Young’s modulus of CL-CNFs synthesized in DIW was also higher than the ones prepared in DMF. To obtain higher conductivity through chemical cross-linking, all the conductivity of CL-CNFs was higher than uncross-linked
CNF (449.24 S/cm) in Fig. 2(b). The junction resistance between CNTs in CNF almost dominated the overall electrical transport, which mainly came from inter-tube contact. The reason was functional CNTs formed a conjugated system in the CL-CNF. The system derived from the interaction of chemical bonding between functional CNTs that formed conjugated structures and made the CNTs together as the CNT wall structures. Moreover, conjugated crosslinking points provided paths for the electron transferring and reduced the inter-tube contact resistance. As a result, the resistance of the CL-CNFs decreased significantly, and their conductivity increased. ECL-CNFs possessed of the higher conductivity than ACL-CNFs prepared in the same solution systems. The conductive paths for electrons in ECL-CNFs were shorted more by powerful ester bonds. Meanwhile, the conductivity of CL-CNFs prepared in DIW was much higher than the CL-CNFs synthesized in DMF. In the synthesis process of CNF, part of functional CNTs directional connecting in DIW system led inter-tube contact increasing, so that contact resistance decreased further. 4. Conclusions In summary, this work provided a series of preparation methods of CL-CNF, using functional CNTs via esterification and acylation reactions in DIW and DMF respectively. Compared with mechanical and electrical properties of all the CL-CNFs, synthetic method of ECL-CNF prepared in DIW was optimal one in this work. Its tensile strength and Young’s modulus were increased by 263% and 190% than uncross-linked CNF, and conductivity enhanced about 2 times. The improvement on properties of CL-CNF derived from the inter-tube interaction transformed from weaker Van der Waals force into stronger chemical bond. From characterization and analysis, it could be concluded that the strength of the ester bond was stronger than acylation and part of cross-linked CNTs generated in DIW system before UV irradiation. Therefore, improvement of the overall performance of ECL-CNF prepared in DIW was based on its unique micro-structures, and the ECL-CNF prepared in DIW would become a candidate for engineering applications. Acknowledgements This work is supported by the National Natural Science Foundation of China (Grant Nos. 11225211, 11272106) and the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 11421091).
Q. Xia et al. / Materials Letters 231 (2018) 190–193
References [1] J.G. Park, J. Smithyman, C.Y. Lin, A. Cooke, A.W. Kismarahardja, S. Li, R. Liang, J. S. Brooks, C. Zhang, B. Wang, Effects of surfactants and alignment on the physical properties of single-walled carbon nanotube buckypaper, J. Appl. Phys. 106 (2009) 104310. [2] E. Yazici, S. Yanik, M.B. Yilmaz, Graphene oxide nano-domain formation via wet chemical oxidation of graphene, Carbon 111 (2017) 822–827. [3] S. Iijima, Helical microtubules of graphitic carbon, Nature 354 (1991) 56–58. [4] H. Chu, Z. Zhang, Y. Liu, J. Leng, Self-heating fiber reinforced polymer composite using meso/macropore carbon nanotube paper and its application in deicing, Carbon 66 (2014) 154–163. [5] L. Tang, A. Iddya, X. Zhu, A.V. Dudchenko, W. Duan, C. Turchi, J. Vanneste, T.Y. Cath, D. Jassby, Enhanced flux and electrochemical cleaning of silicate scaling on carbon nanotube-coated membrane distillation membranes treating geothermal brines, ACS Appl. Mater. Interfaces 9 (2017) 38594–38605.
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[6] W. Duan, A. Ronen, S. Walker, D. Jassby, Polyaniline-coated carbon nanotube ultrafiltration membranes: enhanced anodic stability for in situ cleaning and electro-oxidation processes, ACS Appl. Mater. Interfaces 8 (2016) 22574– 22584. [7] W. Duan, A. Ronen, J.V. Leon, A. Dudchenko, S. Yao, J. Corbala-Delgado, A. Yan, M. Matsumoto, D. Jassby, Treating anaerobic sequencing batch reactor effluent with electrically conducting ultrafiltration and nanofiltration membranes for fouling control, J. Membrane Sci. 504 (2016) 104–112. [8] Q. Liu, M. Li, Z. Wang, Y. Gu, Y. Li, Z. Zhang, Improvement on the tensile performance of buckypaper using a novel dispersant and functionalized carbon nanotubes, Compos. Part A-Appl. Sci. Manuf. 55 (2013) 102–109. [9] J. Zhang, D. Jiang, H.X. Peng, F. Qin, Enhanced mechanical and electrical properties of carbon nanotube buckypaper by in situ cross-linking, Carbon 63 (2013) 125–132. [10] M.B. Jakubinek, B. Ashrafi, J. Guan, M.B. Johnson, M.A. White, B. Simard, 3D chemically cross-linked single-walled carbon nanotube buckypapers, RSC Adv. 4 (2014) 57564–57573.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/mlblue
Self-assembly of cross-linked carbon nanotube films for improvement on mechanical properties and conductivity Qianshan Xia a, Zhichun Zhang a, Yanju Liu b, Jinsong Leng a,⇑ a b
Center for Composite Materials and Structures, No. 2 YiKuang Street, Science Park of Harbin Institute of Technology (HIT), Harbin 150080, PR China Department of Aerospace Science and Mechanics, No. 92 West DaZhi Street, Harbin Institute of Technology (HIT), Harbin 150001, PR China
a r t i c l e
i n f o
Article history: Received 18 March 2018 Received in revised form 20 June 2018 Accepted 10 August 2018 Available online 11 August 2018 Keywords: Carbon nanotubes Cross-linking Thin films
a b s t r a c t A facile strategy for cross-linked carbon nanotube film (CL-CNF) was carried out via self-assembly of carbon nanotubes (CNTs), which was achieved based on esterification and acylation reactions of functional CNTs respectively. Comparing with uncross-linked carbon nanotube film, this strategy could benefit for enhancing mechanical properties of CNF through altering the inter-tube interaction from weaker Van der Waals force to stronger chemical bonding, but not lost its conductivity. The tensile strength and Young’s modulus of CL-CNF were remarkably enhanced, which were higher 263% and 190% than uncross-linked CNF. Meanwhile, conductivity of CNF after cross-linking increased to 210%. In this paper, the forming ester and acylation bonding in CNT network led to differences of their morphology that were observed on nanoscale. This method promoted CL-CNF as a promising material to be applied in water treatment and self-heating materials. Ó 2018 Published by Elsevier B.V.
1. Introduction Owing to their low density and excellent electrical property, carbon materials are obtained more attention, including carbon nanotubes (CNTs) [1] and graphene [2], etc. Since CNT was first found in 1991 [3], CNT and its composites have been widely studied. As a macro-material of CNT, carbon nanotube film (CNF) that is generally manufactured via vacuum based and pressurized filtration method, has potential applications in self-heating [4] and water treatment [5–7] materials, etc. However, friability of CNF restricts its application seriously, because the interaction between CNTs in CNF derives from the weaker Van der Waals force. For example, Wang [1] prepared uncross-linked CNF, and stress and strain of uncross-linked CNF were only 22.1 MPa and 1.5%. Construction of CNF/polymer composite was a way to improve mechanical properties of CNF [8]. Although mechanical properties of CNF could be drastically improved via insulating and rigid resin impregnation, its density increasing, conductivity reducing and flexibility losing were inevitably acquired. Another method was preparation of cross-linked CNF (CL-CNF) by introducing some organic cross linkers, such as benzoquinone [9], epibromohydrin [10], etc. It switched intertube interaction from weaker Van der Waals force to stronger
⇑ Corresponding author. E-mail address: [email protected] (J. Leng). https://doi.org/10.1016/j.matlet.2018.08.054 0167-577X/Ó 2018 Published by Elsevier B.V.
chemical bonding. However, introduction of organic cross linker was equivalent to adding insulator between CNTs, and this method would decrease the electrical conductivity of CNF. To obtain the CNF with better mechanical and electrical properties, several CL-CNFs were first prepared by CNTs with carboxyl, hydroxide radical and amidogen via chemical self-assembly. This method was based on esterification and acylation reactions between functional CNTs in different solution systems, respectively. Moreover, mechanism of various reaction conditions influencing on mechanical properties of CL-CNFs was analyzed in this work.
2. Experimental According to previous report [4], the uncross-linked CNF as control group was prepared by single-wall carbon nanotubes (SWCNTs), and its areal density was 2 mg/cm2. Then the SWCNTs containing carboxyl (SWCNTs-COOH) and hydroxy SWCNTs (SWCNTs-OH), and SWCNTs-COOH and SWCNTs containing amidogen (SWCNTs-NH2) with the weight ratio of 1.05: 1, followed the similar preparation process of uncross-linked CNF, to fabricate esterification and acylation CNFs in deionized water (DIW) and dimethylformamide (DMF) solution systems, respectively. Additionally, all the areal density of esterification and acylation CNFs was prepared with 2 mg/cm2. After peeling from the filter membrane, the CNFs prepared in DIW and DMF systems were undergone UV irradiation for 6 h, for obtaining the esterification and
Q. Xia et al. / Materials Letters 231 (2018) 190–193
acylation CL-CNFs. The esterification and acylation CL-CNFs were designated as ECL-CNFs and ACL-CNFs. The thickness of uncrosslinked CNF, ECL-CNFs and ACL-CNFs prepared in DIW and DMF was 30, 27, 29, 27 and 30 um respectively, which was measured by a micrometer.
191
3. Results and discussion Interaction types between CNTs would impact on the morphology of CNFs. Topological differences could be found in partial enlargement images of surface of uncross-linked CNF, ECL-CNFs
Fig. 1. SEM micrographs of surface, pore size distribution and Gaussian distribution curves of a) uncross-linked CNF, b) ECL-CNF prepared in DIW, c) ECL-CNF prepared in DMF, d) ACL-CNF prepared in DIW and e) ACL-CNF prepared in DMF.
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Q. Xia et al. / Materials Letters 231 (2018) 190–193
Fig. 2. a) Mechanical properties and b) conductivity of uncross-linked CNF, ECL-CNF in DIW, ECL-CNF in DMF, ACL-CNF in DIW and ACL-CNF in DMF.
and ACL-CNFs prepared in DIW and DMF, through comparing with Fig. 1(a–e). The surface of uncross-linked CNF was uneven and porous, and its CNT networks were constructed via random distribution of CNTs. Van der Waals force between CNTs led that the CNTs linked with each other and formed an uncross-linked CNF [4]. Compared with uncross-linked CNF, pore diameters and CNT networks of all the CL-CNFs were smaller and denser, due to the strength of the chemical bond stronger than Van der Waals force. Moreover, the peaks of pore size distribution in Fig. 1(a–e) located at 80–90, 10–15, 15–25, 10–20 and 70–80 nm, respectively. Especially, CNT networks of CL-CNFs prepared in DIW presented much denser structures, and the arrangement of CNTs was more regular than the other three CNFs, owing to cross-linked reaction partly occurring in DIW before UV irradiation. The functional groups were usually attached to caps of CNTs. When functional CNTs were diffused in DIW, the caps of CNTs would be connected regularly by ester and acylation bonds. Fig. 2(a) displayed the tensile strength and Young’s modulus of uncross-linked and CL-CNFs. Moreover, the insert photo was a bending esterification CNF, suggesting it was flexible and robust enough to be manipulated as an ordinary paper. Because strength of the chemical bond of CL-CNFs was stronger than Van der Waals force of uncross-linked CNF, and the cross-linking joints between CNT bundles and CNTs increased the overall inter-tube stress transfer abilities. Therefore, the CL-CNFs possessed the higher tensile strength than uncross-linked CNF (17.82 MPa). Compared with five CNFs, the tensile strength of ECL-CNF prepared in DIW was the maximum (64.61 MPa). Moreover, the tensile strength of ECL-CNFs was greater than ACL-CNFs, because strength of ester bond was more powerful than acylation bonding. Before UV irradiation stage, part of CNTs reacted cross-linking in DIW system, and cross-linking degree of CL-CNF synthesized in DIW was higher than DMF. Thus, CL-CNFs prepared in DIW had the higher tensile strength than the ones synthesized in DMF. Likewise, the Young’s modulus of CLCNFs was also higher than uncross-linked CNF (1.11 GPa), thereinto, ECL-CNF prepared in DIW (3.22 GPa) possessed of the maximum of five CNFs. Owing to the stronger inhibiting effect of the ester bond, the Young’s modulus of ECL-CNFs was higher than ACL-CNFs and it meant the ECL-CNFs had higher stiffness. Due to cross-linking degree of CL-CNF prepared in DIW higher than CL-CNF prepared in DMF, CL-CNFs synthesized in DIW hold more powerful resistance to deformation. Thus, Young’s modulus of CL-CNFs synthesized in DIW was also higher than the ones prepared in DMF. To obtain higher conductivity through chemical cross-linking, all the conductivity of CL-CNFs was higher than uncross-linked
CNF (449.24 S/cm) in Fig. 2(b). The junction resistance between CNTs in CNF almost dominated the overall electrical transport, which mainly came from inter-tube contact. The reason was functional CNTs formed a conjugated system in the CL-CNF. The system derived from the interaction of chemical bonding between functional CNTs that formed conjugated structures and made the CNTs together as the CNT wall structures. Moreover, conjugated crosslinking points provided paths for the electron transferring and reduced the inter-tube contact resistance. As a result, the resistance of the CL-CNFs decreased significantly, and their conductivity increased. ECL-CNFs possessed of the higher conductivity than ACL-CNFs prepared in the same solution systems. The conductive paths for electrons in ECL-CNFs were shorted more by powerful ester bonds. Meanwhile, the conductivity of CL-CNFs prepared in DIW was much higher than the CL-CNFs synthesized in DMF. In the synthesis process of CNF, part of functional CNTs directional connecting in DIW system led inter-tube contact increasing, so that contact resistance decreased further. 4. Conclusions In summary, this work provided a series of preparation methods of CL-CNF, using functional CNTs via esterification and acylation reactions in DIW and DMF respectively. Compared with mechanical and electrical properties of all the CL-CNFs, synthetic method of ECL-CNF prepared in DIW was optimal one in this work. Its tensile strength and Young’s modulus were increased by 263% and 190% than uncross-linked CNF, and conductivity enhanced about 2 times. The improvement on properties of CL-CNF derived from the inter-tube interaction transformed from weaker Van der Waals force into stronger chemical bond. From characterization and analysis, it could be concluded that the strength of the ester bond was stronger than acylation and part of cross-linked CNTs generated in DIW system before UV irradiation. Therefore, improvement of the overall performance of ECL-CNF prepared in DIW was based on its unique micro-structures, and the ECL-CNF prepared in DIW would become a candidate for engineering applications. Acknowledgements This work is supported by the National Natural Science Foundation of China (Grant Nos. 11225211, 11272106) and the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 11421091).
Q. Xia et al. / Materials Letters 231 (2018) 190–193
References [1] J.G. Park, J. Smithyman, C.Y. Lin, A. Cooke, A.W. Kismarahardja, S. Li, R. Liang, J. S. Brooks, C. Zhang, B. Wang, Effects of surfactants and alignment on the physical properties of single-walled carbon nanotube buckypaper, J. Appl. Phys. 106 (2009) 104310. [2] E. Yazici, S. Yanik, M.B. Yilmaz, Graphene oxide nano-domain formation via wet chemical oxidation of graphene, Carbon 111 (2017) 822–827. [3] S. Iijima, Helical microtubules of graphitic carbon, Nature 354 (1991) 56–58. [4] H. Chu, Z. Zhang, Y. Liu, J. Leng, Self-heating fiber reinforced polymer composite using meso/macropore carbon nanotube paper and its application in deicing, Carbon 66 (2014) 154–163. [5] L. Tang, A. Iddya, X. Zhu, A.V. Dudchenko, W. Duan, C. Turchi, J. Vanneste, T.Y. Cath, D. Jassby, Enhanced flux and electrochemical cleaning of silicate scaling on carbon nanotube-coated membrane distillation membranes treating geothermal brines, ACS Appl. Mater. Interfaces 9 (2017) 38594–38605.
193
[6] W. Duan, A. Ronen, S. Walker, D. Jassby, Polyaniline-coated carbon nanotube ultrafiltration membranes: enhanced anodic stability for in situ cleaning and electro-oxidation processes, ACS Appl. Mater. Interfaces 8 (2016) 22574– 22584. [7] W. Duan, A. Ronen, J.V. Leon, A. Dudchenko, S. Yao, J. Corbala-Delgado, A. Yan, M. Matsumoto, D. Jassby, Treating anaerobic sequencing batch reactor effluent with electrically conducting ultrafiltration and nanofiltration membranes for fouling control, J. Membrane Sci. 504 (2016) 104–112. [8] Q. Liu, M. Li, Z. Wang, Y. Gu, Y. Li, Z. Zhang, Improvement on the tensile performance of buckypaper using a novel dispersant and functionalized carbon nanotubes, Compos. Part A-Appl. Sci. Manuf. 55 (2013) 102–109. [9] J. Zhang, D. Jiang, H.X. Peng, F. Qin, Enhanced mechanical and electrical properties of carbon nanotube buckypaper by in situ cross-linking, Carbon 63 (2013) 125–132. [10] M.B. Jakubinek, B. Ashrafi, J. Guan, M.B. Johnson, M.A. White, B. Simard, 3D chemically cross-linked single-walled carbon nanotube buckypapers, RSC Adv. 4 (2014) 57564–57573.