Enhanced Stability of Reduced Graphene Oxide Colloid Using Cross

Apr 21, 2014 - Géssica Seara Faria , Andreza Menezes Lima , Luiz Paulo Brandão , Alberto Pessoa da Costa , Stefania Nardecchia , Alexandre Antunes ...
0 downloads 0 Views 3MB Size
Article pubs.acs.org/JPCC

Enhanced Stability of Reduced Graphene Oxide Colloid Using CrossLinking Polymers Akshaya Kumar Swain† and Dhirendra Bahadur*,‡ †

IITB Monash Research Academy, Department of Metallurgical Engineering and Materials Science, IIT Bombay, Mumbai 400076, India ‡ Department of Metallurgical Engineering and Materials Science, IIT Bombay, Mumbai 400076, India S Supporting Information *

ABSTRACT: Reduced graphene oxide (RGO) synthesized by subsequent oxidation and reduction suffers from agglomeration within a few hours/days of its preparation. The stability of RGO is enhanced (no agglomeration for more than 23 months) by allowing two cross-linking polymers that prevent restacking; this increases the solubility and biocompatibility of RGO. The RGO dispersion follows an electrosteric stabilization mechanism. Various theoretical models were adopted to understand this behavior by estimating the potential barrier for agglomeration, surface free energy, and Hansen solubility parameters of the dispersion. As-prepared RGO is found to be biocompatible and has luminescent properties.



INTRODUCTION Chemistry-rich graphite oxide (GO) and its derivatives are amphiphilic in nature due to the presence of a hydrophobic basal plane and hydrophilic edges.1 So, the flocculation of reduced graphene oxide (RGO) that leads to agglomeration is spontaneous by virtue of its dominant hydrophobic interaction over an RGO−solvent interaction. Thus, using a single surfactant or a polymer with one repeating monomer is insufficient to deal with the wide range of forces that are present in RGO dispersions.2−9 This may also be due to the presence of two different length scales (thickness in Å and lateral size in μm) in GO derivatives. This property makes it behave both as a molecule and a colloid.1 RGO, prepared chemically by the classical oxidation− reduction technique, is cheap, easy, and scalable to realize commercial applications on a large scale. The various applications of RGO in major industries such as paints, coatings, pharmaceuticals, and the like demand that its stability be maintained for prolonged periods. Thus, there have been many attempts to make a stable graphene/RGO suspension.2−10 In fact, Hernandez et al. tested 40 solvents in order to facilitate the understanding of the solubility of graphene and to increase its stability in a dispersion.11 Park et al. reported colloidal dispersions of RGO in a variety of organic solvent mixtures.12 Lotya et al. obtained a maximum stability of ∼6 weeks, using a surfactant.2 Jo et al. obtained a maximum stability of six months for RGO by noncovalent functionalization using conducting polymers. 10 RGO, with excess hydrazine/reducing agents, gets agglomerated readily.13 A summary of the stability of graphene/RGO, which has already been reported, is presented in Table S1 (Supporting Information). Even though the solubility of GO/RGO in a wide range of solvents has been studied, the prolonged stability © 2014 American Chemical Society

of these dispersions remains a challenge. This limits the use of RGO in major industrial applications. In this study, we describe a simple technique that uses two cross-linking polymers (CLPs), polyvinylpyrrolidone (PVP) and poly(vinyl alcohol) (PVA) during reduction, in order to enhance the stability of RGO dispersion significantly. The cross-linking between PVA and PVP is a well established fact in the literature. The cross-link generally occurs at the site of radical formation on the OH group of PVA and/or at the main chain of the polymers. The OH groups in PVA and the CO groups in PVP cross-link through hydrogen bonding.14 Also, the dispersion is biocompatible due to the presence of the two polymers (PVP and PVA). This renders it a potential material for various industrial applications (including biomedical applications) that require a colloid to stand for a few years without sedimentation or agglomeration. To the best of our knowledge, there is no report so far that claims stabilization of a RGO dispersion for more than six months.



SYNTHESIS AND CHARACTERIZATION OF MATERIALS Natural graphite powder (purity >99.99%, average particle size few μg/mL), which might result from oxidative stress and reactive oxygen species that are abundantly present in both GO and RGO.52,53 In addition, aggregation of RGO in the dispersion blocks the cells to obtain sufficient nutrients for the growth of the cells.54 Thus, a welldispersed stable dispersion would facilitate cell growth. In general, the biocompatibility of a material depends mainly on

how well proteins mediate the interactions between the cell and the corresponding material. The cellular interaction can be tuned by functionalizing the RGO with suitable polymers. Since RGO is linked to the polymers (PVA and PVP) through defect sites, its biocompatibility will be governed mainly by the cell− polymer interaction. The cell membrane finds itself in a biofriendly environment that comprises these two polymers and the media mostly, forming an extra cellular matrix for the cells.55 This matrix provides the essential nutrients for cell growth resulting in a biocompatible system. Our experiments suggest an excellent method for the stabilization of RGO and making it biocompatible. The biocompatibility of SRG comes from the presence of the two excellent biocompatible polymers (PVP/PVA) that are bonded to RGO. Thus, we expect this material to be a potential material for various bioapplications.



CONCLUSION To conclude, we report a simple approach to obtain high solubility and enhanced stability of RGO by using cross-linking polymers as an add-on to classical GO reduction. The experimental data supports the theoretical arguments obtained through various models. The DLVO theory predicts a potential barrier for the agglomeration. SFE of the polymer−matrix demands steric stabilization, and HSPs of the constituents of SRG confirms the solubility. SRG was found to be biocompatible with luminescent properties. Thus, we believe that SRG would be a potential candidate for several promising industrial applications including bioapplications that demand prolonged stability of a dispersion.



ASSOCIATED CONTENT

* Supporting Information S

Experimental methods for preparation of GO, SRG, PVPA; sample preparation techniques for various characterizations; Table S1 represents the summary of the stabilization studies of graphene/RGO; Table S2 represents the LW and AB components of PVA, PVP, water, and PTFE; and Figure S1 represents the morphology of dried SRG on a silicon substrate. This material is available free of charge via the Internet at http://pubs.acs.org.



AUTHOR INFORMATION

Corresponding Author

*Phone: +91 22 2576 7632; fax: +91 22 2572 6975; e-mail: [email protected]. 9455

dx.doi.org/10.1021/jp500205n | J. Phys. Chem. C 2014, 118, 9450−9457

The Journal of Physical Chemistry C

Article

Notes

site Electrodes for Flexible Transparent Organic Field-Effect Transistors. J. Phys. Chem. C 2012, 116, 7520−7525. (17) Delbecq, F.; Kono, F.; Kawai, T. Preparation of PVP-PVAExfoliated Graphite Cross-Linked Composite Hydrogels for the Incorporation of Small Tin Nanoparticles. Eur. Polym. J. 2013, 49, 2654−2659. (18) Prakash, A.; Chandra, S.; Bahadur, D. Structural, Magnetic, and Textural Properties of Iron Oxide-Reduced Graphene Oxide Hybrids and Their Use for the Electrochemical Detection of Chromium. Carbon 2012, 50, 4209−4219. (19) Swain, A. K.; Li, D.; Bahadur, D. UV-Assisted Production of Ferromagnetic Graphitic Quantum Dots from Graphite. Carbon 2013, 57, 346−356. (20) Georgakilas, V.; Otyepka, M.; Bourlinos, A. B.; Chandra, V.; Kim, N.; Kemp, K. C.; Hobza, P.; Zboril, R.; Kim, K. S. Functionalization of Graphene: Covalent and Non-covalent Approaches, Derivatives and Applications. Chem. Rev. 2012, 112, 6156−6214. (21) Ma, R. Y.; Xiong, D. S.; Miao, F.; Zhang, J. F.; Peng, Y. Novel PVP/PVA Hydrogels for Articular Cartilage Replacement. Mater. Sci. Eng., C 2009, 29, 1979−1983. (22) Bagri, A.; Mattevi, C.; Acik, M.; Chabal, Y. J.; Chhowalla, M.; Shenoy, V. B. Structural Evolution during the Reduction of Chemically Derived Graphene Oxide. Nat. Chem. 2010, 2, 581−587. (23) Dreyer, D. R.; Park, S.; Bielawski, C. W.; Ruoff, R. S. The Chemistry of Graphene Oxide. Chem. Soc. Rev. 2010, 39, 228−240. (24) Hawaldar, R.; Merino, P.; Correia, M. R.; Bdikin, I.; Gracio, J.; Mendez, J.; Martin-Gago, J. A.; Singh, M. K. Large-Area HighThroughput Synthesis of Monolayer Graphene Sheet by Hot Filament Thermal Chemical Vapor Deposition. Sci. Rep. 2012, 2. (25) Patil, A. J.; Vickery, J. L.; Scott, T. B.; Mann, S. Aqueous Stabilization and Self-Assembly of Graphene Sheets into Layered BioNanocomposites Using DNA. Adv. Mater. 2009, 21, 3159−3164. (26) Xiong, Y.; Washio, I.; Chen, J.; Cai, H.; Li, Z. Y.; Xia, Y. Poly(vinyl pyrrolidone): A Dual Functional Reductant and Stabilizer for the Facile Synthesis of Noble Metal Nanoplates in Aqueous Solutions. Langmuir 2006, 22, 8563−8570. (27) Hazra, K. S.; Rafiee, J.; Rafiee, M. A.; Mathur, A.; Roy, S. S.; McLauhglin, J.; Koratkar, N.; Misra, D. S. Thinning of Multilayer Graphene to Monolayer Graphene in a Plasma Environment. Nanotechnology 2011, 22. (28) Hu, N. T.; Gao, R. G.; Wang, Y. Y.; Wang, Y. F.; Chai, J.; Yang, Z.; Kong, E. S. W.; Zhang, Y. F. The Preparation and Characterization of Non-covalently Functionalized Graphene. J. Nanosci. Nanotechnol. 2012, 12, 99−104. (29) Bates, F. S. Polymer-Polymer Phase-Behavior. Science 1991, 251, 898−905. (30) May, P.; Khan, U.; Hughes, J. M.; Coleman, J. N. Role of Solubility Parameters in Understanding the Steric Stabilization of Exfoliated Two-Dimensional Nanosheets by Adsorbed Polymers. J. Phys. Chem. C 2012, 116, 11393−11400. (31) Bourlinos, A. B.; Georgakilas, V.; Zboril, R.; Steriotis, T. A.; Stubos, A. K.; Trapalis, C. Aqueous-Phase Exfoliation of Graphite in the Presence of Polyvinylpyrrolidone for the Production of WaterSoluble Graphenes. Solid State Commun. 2009, 149, 2172−2176. (32) Kou, L.; Gao, C. Bioinspired Design and Macroscopic Assembly of Poly(vinyl alcohol)-Coated Graphene into Kilometers-Long Fibers. Nanoscale 2013, 5, 4370−4378. (33) Dao, T. D.; Lee, H. I.; Jeong, H. M.; Kim, B. K. Direct Covalent Modification of Thermally Exfoliated Graphene Forming Functionalized Graphene Stably Dispersible in Water and Poly(vinyl alcohol). Colloid Polym. Sci. 2013, 291, 2365−2374. (34) Swain, A. K.; Bahadur, D. Facile Synthesis of Twisted Graphene Solution from Graphite-KCl. RSC Adv. 2013, 3, 19243−19246. (35) Smith, R. J.; Lotya, M.; Coleman, J. N. The Importance of Repulsive Potential Barriers for the Dispersion of Graphene Using Surfactants. New J. Phys. 2010, 12.

The authors declare no competing financial interest.

■ ■

ACKNOWLEDGMENTS The authors would like to thank DST-Nanomission and IITBMonash Research Academy for the financial support. REFERENCES

(1) Kim, J.; Cote, L. J.; Kim, F.; Yuan, W.; Shull, K. R.; Huang, J. X. Graphene Oxide Sheets at Interfaces. J. Am. Chem. Soc. 2010, 132, 8180−8186. (2) Lotya, M.; Hernandez, Y.; King, P. J.; Smith, R. J.; Nicolosi, V.; Karlsson, L. S.; Blighe, F. M.; De, S.; Wang, Z. M.; McGovern, I. T.; Duesberg, G. S.; Coleman, J. N. Liquid Phase Production of Graphene by Exfoliation of Graphite in Surfactant/Water Solutions. J. Am. Chem. Soc. 2009, 131, 3611−3620. (3) Lotya, M.; King, P. J.; Khan, U.; De, S.; Coleman, J. N. HighConcentration, Surfactant-Stabilized Graphene Dispersions. ACS Nano 2010, 4, 3155−3162. (4) Stankovich, S.; Piner, R. D.; Chen, X.; Wu, N.; Nguyen, S. T.; Ruoff, R. S. Stable Aqueous Dispersions of Graphitic Nanoplatelets via the Reduction of Exfoliated Graphite Oxide in the Presence of Poly(sodium 4-styrenesulfonate). J. Mater. Chem. 2006, 16, 155−158. (5) Das, S.; Wajid, A. S.; Shelburne, J. L.; Liao, Y. C.; Green, M. J. Localized in Situ Polymerization on Graphene Surfaces for Stabilized Graphene Dispersions. ACS Appl. Mater. Interfaces 2011, 3, 1844− 1851. (6) Ou, E.; Xie, Y.; Peng, C.; Song, Y.; Peng, H.; Xiong, Y.; Xu, W. High Concentration and Stable Few-Layer Graphene Dispersions Prepared by the Exfoliation of Graphite in Different Organic Solvents. RSC Adv. 2013, 3, 9490−9499. (7) Karthick, R.; Brindha, M.; Selvaraj, M.; Ramu, S. Stable Colloidal Dispersion of Functionalized Reduced Graphene Oxide in Aqueous Medium for Transparent Conductive Film. J. Colloid Interface Sci. 2013, 406, 69−74. (8) Luo, J.; Jiang, S.; Wu, Y.; Chen, M.; Liu, X. Synthesis of Stable Aqueous Dispersion of Graphene/Polyaniline Composite Mediated by Polystyrene Sulfonic Acid. J. Polym. Sci., Polym. Chem. 2012, 50, 4888− 4894. (9) Park, S.; An, J. H.; Piner, R. D.; Jung, I.; Yang, D. X.; Velamakanni, A.; Nguyen, S. T.; Ruoff, R. S. Aqueous Suspension and Characterization of Chemically Modified Graphene Sheets. Chem. Mater. 2008, 20, 6592−6594. (10) Jo, K.; Lee, T.; Choi, H. J.; Park, J. H.; Lee, D. J.; Lee, D. W.; Kim, B. S. Stable Aqueous Dispersion of Reduced Graphene Nanosheets via Non-covalent Functionalization with Conducting Polymers and Application in Transparent Electrodes. Langmuir 2011, 27, 2014−2018. (11) Hernandez, Y.; Lotya, M.; Rickard, D.; Bergin, S. D.; Coleman, J. N. Measurement of Multicomponent Solubility Parameters for Graphene Facilitates Solvent Discovery. Langmuir 2010, 26, 3208− 3213. (12) Park, S.; An, J. H.; Jung, I. W.; Piner, R. D.; An, S. J.; Li, X. S.; Velamakanni, A.; Ruoff, R. S. Colloidal Suspensions of Highly Reduced Graphene Oxide in a Wide Variety of Organic Solvents. Nano Lett. 2009, 9, 1593−1597. (13) Li, D.; Muller, M. B.; Gilje, S.; Kaner, R. B.; Wallace, G. G. Processable Aqueous Dispersions of Graphene Nanosheets. Nat. Nanotechnol. 2008, 3, 101−105. (14) Ping, Z. H.; Nguyen, Q. T.; Neel, J. Investigations of Poly(vinyl alcohol) Poly(N-vinyl-2-pyrrolidone) Blends 0.2. Influence of the Molecular-Weights of the Polymer Components on Crystallization. Makromol. Chem. 1990, 191, 185−198. (15) Zhang, Y.; Hu, W.; Li, B.; Peng, C.; Fan, C.; Huang, Q. Synthesis of Polymer-Protected Graphene by Solvent-Assisted Thermal Reduction Process. Nanotechnology 2011, 22, 345601. (16) Lim, S.; Kang, B.; Kwak, D.; Lee, W. H.; Lim, J. A.; Cho, K. Inkjet-Printed Reduced Graphene Oxide/Poly(vinyl alcohol) Compo9456

dx.doi.org/10.1021/jp500205n | J. Phys. Chem. C 2014, 118, 9450−9457

The Journal of Physical Chemistry C

Article

(36) Das, P. K.; Bhattacharjee, S.; Moussa, W. Electrostatic Double Layer Force between Two Spherical Particles in a Straight Cylindrical Capillary: Finite Element Analysis. Langmuir 2003, 19, 4162−4172. (37) Israelachvili, J. N.; McGuiggan, P. M. Forces between Surfaces in Liquids. Science 1988, 241, 795−800. (38) Fennell Evans, D.; Wennerström, J. The Colloidal Domain: Where Physics, Chemistry, Biology, and Technology Meet; Wiley-VCH: Weinheim, Germany, 1999; p 672. (39) Vanoss, C. J.; Chaudhury, M. K.; Good, R. J. Interfacial LifshitzVanderwaals and Polar Interactions in Macroscopic Systems. Chem. Rev. 1988, 88, 927−941. (40) Azeredo, J.; Visser, J.; Oliveira, R. Exopolymers in Bacterial Adhesion: Interpretation in Terms of DLVO and XDLVO Theories. Colloids Surf., B 1999, 14, 141−148. (41) Rafiee, J.; Mi, X.; Gullapalli, H.; Thomas, A. V.; Yavari, F.; Shi, Y. F.; Ajayan, P. M.; Koratkar, N. A. Wetting Transparency of Graphene. Nat. Mater. 2012, 11, 217−222. (42) Rafiee, J.; Rafiee, M. A.; Yu, Z. Z.; Koratkar, N. Superhydrophobic to Superhydrophilic Wetting Control in Graphene Films. Adv. Mater. 2010, 22, 2151−2154. (43) Raj, R.; Maroo, S. C.; Wang, E. N. Wettability of Graphene. Nano Lett. 2013, 13, 1509−1515. (44) Vanoss, C. J.; Good, R. J.; Chaudhury, M. K. The Role of van der Waals Forces and Hydrogen Bonds in “Hydrophobic Interactions” between Biopolymers and Low Energy Surfaces. J. Colloid Interface Sci. 1986, 111, 378−390. (45) Good, R. J. Estimation of Surface Energies from Contact Angles. Nature 1966, 212, 276−277. (46) Napper, D. H. Steric Stabilization. J. Colloid Interface Sci. 1977, 58, 390−407. (47) Zhulina, E. B.; Borisov, O. V.; Priamitsyn, V. A. Theory of Steric Stabilization of Colloid Dispersions by Grafted Polymers. J. Colloid Interface Sci. 1990, 137, 495−511. (48) Einarson, M. B.; Berg, J. C. Effect of Salt on Polymer Solvency: Implications for Dispersion Stability. Langmuir 1992, 8, 2611−2615. (49) Tandon, V.; Bhagavatula, S. K.; Nelson, W. C.; Kirby, B. J. Zeta Potential and Electroosmotic Mobility in Microfluidic Devices Fabricated from Hydrophobic Polymers: 1. The Origins of Charge. Electrophoresis 2008, 29, 1092−1101. (50) Park, J.; Yan, M. Covalent Functionalization of Graphene with Reactive Intermediates. Acc. Chem. Res. 2013, 46, 181−189. (51) Faure, B.; Salazar-Alvarez, G.; Ahniyaz, A.; Villaluenga, I.; Berriozabal, G.; De Miguel, Y. R.; Bergstrom, L. Dispersion and Surface Functionalization of Oxide Nanoparticles for Transparent Photocatalytic and UV-Protecting Coatings and Sunscreens. Sci. Technol. Adv. Mater. 2013, 14. (52) Das, S.; Singh, S.; Singh, V.; Joung, D.; Dowding, J. M.; Reid, D.; Anderson, J.; Zhai, L.; Khondaker, S. I.; Self, W. T.; Seal, S. Oxygenated Functional Group Density on Graphene Oxide: Its Effect on Cell Toxicity. Part. Part. Syst. Charact. 2013, 30, 148−157. (53) Wojtoniszak, M.; Chen, X. C.; Kalenczuk, R. J.; Wajda, A.; Lapczuk, J.; Kurzewski, M.; Drozdzik, M.; Chu, P. K.; Borowiak-Palen, E. Synthesis, Dispersion, and Cytocompatibility of Graphene Oxide and Reduced Graphene Oxide. Colloids Surf., B 2012, 89, 79−85. (54) Cheng, C.; Nie, S.; Li, S.; Peng, H.; Yang, H.; Ma, L.; Sun, S.; Zhao, C. Biopolymer Functionalized Reduced Graphene Oxide with Enhanced Biocompatibility via Mussel Inspired Coatings/Anchors. J. Mater. Chem. B 2013, 1, 265. (55) Chen, H.; Yuan, L.; Song, W.; Wu, Z.; Li, D. Biocompatible Polymer Materials: Role of Protein−Surface Interactions. Prog. Polym. Sci. 2008, 33, 1059−1087.

9457

dx.doi.org/10.1021/jp500205n | J. Phys. Chem. C 2014, 118, 9450−9457