Polyurethane Nanocomposites Based on Layered Double Hydroxides: A Review on Their Syntheses and Applications

Document Type : Review

Authors

1 Department of Polymer Chemistry, Faculty of Chemical, University of Isfahan, Postal Code 81746-73441, Isfahan, Iran

2 Department of Polyurethane and Advanced Materials, Faculty of Science, Iran Polymer and Petrochemical Institute, P.O. Box 14975-112, Tehran, Iran

Abstract

Nowadays, polymer nanocomposites have attracted much attention in research activities due to their high mechanical strength, high thermal stability, low-cost, with possibility for their applications in many areas. Polyurethanes (PUs), as a main group of polymers, show a diverse and controllable range of physical and mechanical properties due to their tailored properties depending on the nature of precursors like polyols and isocyanates. This diversity and controllability of their properties make different types of PUs (elastomers, fibers, foams, hydrogels, and coatings) preferred candidates for a variety of uses, including transportation, clothing, furniture, and biomaterials. Many studies have been performed on polyurethane nanocomposites using different types of nanostructures such as graphene-like nanosheets, carbon nanotubes, metal oxides, and so on. Layered double hydroxides (LDHs) are eco-friendly layered mineral nanostructures with positively charged layers and anion-exchange capability. Depending on the types of anions and structure of layers, the LDHs nanostructures can be used broadly for the applications such as catalysts, drug delivery, separation technology, and also as a UV absorbent, corrosion, and a flame inhibitor for polymers. Recently, LDHs nanostructures are used in the fabrication of polyurethane nanocomposites to improve their mechanical, thermal, and flame properties. In this review, in addition to the description of LDH nanostructures, polyurethanes and their applications, LDH-based polyurethane nanocomposites are discussed in detail.

Keywords


  1. Rong M.Z., Zhang M.Q., Zheng Y.X., Zeng H.M., Walter R., and Friedrich K., Structure–Property Relationships of Irradiation Grafted Nano-Inorganic Particle Filled Polypropylene Composites, Polymer42, 167-183, 2001.
  2. Ramakrishna S., Mayer J., Wintermantel E., and Leong K.W., Biomedical Applications of Polymer-Composite Materials: A Review, Compos. Sci. Technol.61, 1189-1224, 2001.
  3. Bunsell A.R. and Renard J., Fundamentals of Fibre Reinforced Composite Materials, 1st ed., CRC, 398, 2005.
  4. Srivatsan T.S., Ibrahim I.A., Mohamed F.A., and Lavernia E.J., Processing Techniques for Particulate-Reinforced Metal Aluminium Matrix Composites, J. Mater. Sci.26, 5965-5978, 1991.
  5. Rothon R.N., Particulate Fillers for Polymers, iSmithers Rapra, 12, 10-23, 2012.
  6. Clyne T.W. and Hull D., An Introduction to Composite Materials, 3st ed., Cambridge University, 283-305, 2019.
  7. Kamigaito O., What Can be Improved by Nanometer Composites?, J. Jpn. Soc. Powder Powder Metall., 38, 315-321, 1991.
  8. Leng J. and Lau A.K.T., Multifunctional Polymer Nanocomposites, CRC, 14-16, 2010. 
  9. Paul D.R. and Robeson L.M., Polymer Nanotechnology: Nanocomposites, Polymer49, 3187-3204, 2008.
  10. Ajayan P.M., Schadler L.S., and Braun P.V, Nanocomposite Science and Technology, John Wiley and Sons, 2006. 
  11. Tian Z., Hu H., and Sun Y., A Molecular Dynamics Study of Effective Thermal Conductivity in Nanocomposite, Int. J. Heat Mass Transf.61, 577-582, 2013.
  12. Liao K., Schultesiz C.R., Hunston D.L., and Brinson L., Long-Term Durability of Fiber-Reinforced Polymer-Matrix Composite Materials for Infrastructure Applications: A Review, Adv. Mater.30, 3-40, 1998.
  13. Khan W.S., Hamadneh N., and Khan W.A., Polymer Nanocomposites–Synthesis Techniques, Classification and Properties, Science and Applications of Tailored Nanostructures, One Central (OCP), 2016.
  14. Unalan I.U., Cerri G., Marcuzzo E., Cozzolino C.A., and Farris S., Nanocomposite Films and Coatings Using Inorganic Nanobuilding Blocks (NBB): Current Applications and Future Opportunities in the Food Packaging Sector, RSC Adv., 4, 29393-29428, 2014.
  15. Manias E., Nanocomposites: Stiffer by Design, Nat. Mater., 6, 9-11, 2007.
  16. Kuilla T., Bhadra S., Yao D., Kim N.H., Bose S., and Lee J.H., Recent Advances in Graphene Based Polymer Composites, Prog. Polym. Sci., 35, 1350-1375, 2010.
  17. Yang X., Li L., Shang S., and Tao X.M., Synthesis and Characterization of Layer-Aligned Poly(vinyl alcohol)/Graphene Nanocomposites, Polymer51, 3431-3435, 2010.
  18. Cernei E.R., Maxim A., Maxim D.C., Mavru R.B., and Zegan G., Textural Properties of Amoxicillin-Anionic Clays Composites for Possible Oral Diseases Uses, Rev. Chim.67, 1306-1308, 2016.
  19. Khan A.I. and O’Hare D., Intercalation Chemistry of Layered Double Hydroxides: Recent Developments and Applications, J. Mater. Chem.12, 3191-3198, 2002.
  20. Miyata S., The Syntheses of Hydrotalcite-Like Compounds and Their Structures and Physico-Chemical Properties I: The Systems Mg2+-Al3+-NO3-, Mg2+-Al3+-Cl-, Mg2+-Al3+-ClO4-, Ni2+-Al3+-Cl-and Zn2+-Al3+-Cl, Clays Clay Miner.23, 369-375, 1975.
  21. Li C., Wei M., Evans D.G., and Duan X., Layered Double Hydroxide-Based Nanomaterials as Highly Efficient Catalysts and Adsorbents, Small10, 4469-4486, 2014.
  22. Moujahid E.M., Besse J.P., and Leroux F., Synthesis and Characterization of a Polystyrene Sulfonate Layered Double Hydroxide Nanocomposite. In-Situ Polymerization vs. Polymer Incorporation, J. Mater. Chem.12, 3324-3330, 2002.
  23. You Y., Zhao H., and Vance G.F., Hybrid Organic–Inorganic Derivatives of Layered Double Hydroxides and Dodecyl Benzene Sulfonate: Preparation and Adsorption Characteristics, J. Mater. Chem.12, 907-912, 2002.
  24. Saunders K.J., Polyurethanes. Organic Polymer Chemistry, Springer, Dordrecht, 358-387, 1988.
  25. Lee J.H., Zhang W., Ryu H.J., Choi G., Choi J.Y., and Choy J.H., Enhanced Thermal Stability and Mechanical Property of EVA Nanocomposites upon Addition of Organo-Intercalated LDH Nanoparticles, Polymer, 177, 274-281, 2019.
  26. Mallakpour S., Dinari M., and Hatami M., Novel Nanocomposites of Poly(vinyl alcohol) and Mg-Al Layered Double Hydroxide Intercalated with Diacid N-tetrabromophthaloyl-Aspartic, J. Therm. Anal. Cal., 120, 1293-1302, 2015.
  27. Du P., Qiu S., Liu C., Liu G., Zhao H., and Wang L., In Situ Polymerization of Sulfonated Polyaniline in Layered Double Hydroxide Host Matrix for Corrosion Protection, New. J. Chem42, 4201-4209, 2018.
  28. Lowinger M., Barrett S., Zhang F., and Williams R., Sustained Release Drug Delivery Applications of Polyurethanes, Int. J. Pharm., 10, 55, 2018.
  29. Nalawade P., Aware B., Kadam V.J., and Hirlekar R.S., Layered Double Hydroxides: A Review, J. Sci. Indust. Res., 68, 267-272, 2009.
  30. Tang P., Feng Y., and Li D., Facile Synthesis of Multicolor Organic–Inorganic Hybrid Pigments Based on Layered Double Hydroxides, Dyes Pigm., 104, 131-136, 2014.
  31. Everaert M., Layered Double Hydroxides as Slow-Release Phosphorus Fertilizer, 10, 2018.
  32. Shafiei S., Birgani Z.T., Darvish A., Azimi M.S., and Solati-Hashjin M., Layered Double Hydroxides for Diagnostic Applications, International Congress of Evaluation of Medical Diagnosis Modern Technologies, Tehran, Iran, 790-793, 2008.
  33. Nakayama H., Wada, N., and Tsuhako M., Intercalation of Amino Acids and Peptides into Mg–Al Layered Double Hydroxide by Reconstruction Method, Int. J. Pharm.269, 469-478, 2004.
  34. Liu Z., Ma R., Osada M., Iyi N., Ebina Y., Takada K., and Sasaki T., Synthesis, Anion Exchange, and Delamination of Co-Al Layered Double Hydroxide: Assembly of the Exfoliated Nanosheet/Polyanion Composite Films and Magneto-Optical Studies, J. Am. Chem. Soc.128, 4872-4880, 2006.
  35. Meyn M., Beneke K., and Lagaly G., Anion-Exchange Reactions of Layered Double Hydroxides, Inorg. Chem.29, 5201-5207, 1990.
  36. Benício L.P.F., Silva R.A., Lopes J.A., Eulálio D., Santos R.M.M.D., Aquino L.A.D., and Tronto J., Layered Double Hydroxides: Nanomaterials for Applications in Agriculture, Rev. Bras. Cienc. Solo., 39, 1-13, 2015.
  37. Chubar N., Gerda V., Megantari O., Mičušík M., Omastova M., Heister K., and Fraissard J., Applications Versus Properties of Mg–Al Layered Double Hydroxides Provided by Their Syntheses Methods: Alkoxide and Alkoxide-Free Sol-Gel Syntheses and Hydrothermal Precipitation, Chem. Eng. J., 234, 284-299, 2013.
  38. Tao Q., Zhang Y., Zhang X., Yuan P., and He H., Synthesis and Characterization of Layered Double Hydroxides with a High Aspect Ratio, J. Solid State Chem.179, 708-715, 2006.
  39. Choy J.H., Park M., and Oh J.M., Bio-Nanohybrids Based on Layered Double Hydroxide, Curr. Nanosci.2, 275-281, 2006.
  40. Hu H., Yuan Y., and Shi W., Preparation of Waterborne Hyperbranched Polyurethane Acrylate/LDH Nanocomposite, Prog. Org. Coat., 75, 474-479, 2012.
  41. Li E., Xu Z. P., and Rudolph V., MgCoAl–LDH Derived Heterogeneous Catalysts for the Ethanol Transesterification of Canola Oil to Biodiesel, Appl. Catal. B: Environ., 88, 42-49, 2009.
  42. Mohammadi A., Abdolvand H., and Isfahani A.P., Alginate Beads Impregnated with Sulfonate Containing Calix[4]arene Intercalated Layered Double Hydroxides: In situ Preparation, Characterization and Methylene Blue Adsorption Studies, Int. J. Biol. Macromol., 146, 89-98, 2020.
  43. Alibakhshi E., Ghasemi E., Mahdavian M., and Ramezanzadeh B., Corrosion Inhibitor Release from Zn-Al-[PO 3-4]-[CO2-3] Layered Double Hydroxides Nanoparticles, J. Prog. Color Color Coat.9, 231-246, 2016.
  44. Zhao Y., Zhao Y., Waterhouse G.I., Zheng L., Cao X., Teng F., and Zhang T., Layered-Double-Hydroxide Nanosheets as Efficient Visible-Light-Driven Photocatalysts for Dinitrogen Fixation, Adv. Mater.29, 7168-7173, 2017.
  45. Veschambres C., Halma M., Bourgeat-Lami E., Chazeau L., Dalmas F., and Prevot V., Layered Double Hydroxides: Efficient Fillers for Waterborne Nanocomposite Films, Appl. Clay Sci.130, 55-61, 2016.
  46. Rives V., del Arco M., and Martín C., Layered Double Hydroxides as Drug Carriers and for Controlled Release of Non-Steroidal Antiinflammatory Drugs (NSAIDs): A Review, J. Control. Release169, 28-39, 2013.
  47. Matusinovic Z., Lu H., and Wilkie C.A., The Role of Dispersion of LDH in Fire Retardancy: The Effect of Dispersion on Fire Retardant Properties of Polystyrene/Ca−Al Layered Double Hydroxide Nanocomposites, Polym. Degrad. Stab.97, 1563-1568, 2012.
  48. Phua Y.J., Chow W.S., and Mohd Ishak Z.A., Reactive Processing of Maleic Anhydride-Grafted Poly(butylene succinate) and the Compatibilizing Effect on Poly(butylene succinate) Nanocomposites, Express Polym. Lett.7, 340-354, 2013.
  49. Huang Z., Wu P., Lu Y., Wang X., Zhu N., and Dang Z., Enhancement of Photocatalytic Degradation of Dimethyl Phthalate with Nano-TiO2 Immobilized onto Hydrophobic Layered Double Hydroxides: a Mechanism Study, J. Hazard Mater.246, 70-78, 2013.
  50. Xu Z.P., Stevenson G., Lu C.Q., and Lu G.Q., Dispersion and Size Control of Layered Double Hydroxide Nanoparticles in Aqueous Solutions, J. Phys. Chem. B110, 16923-16929, 2006.
  51. Subramanian T., Dhakshinamoorthy A., and Pitchumani K., Amino Acid Intercalated Layered Double Hydroxide Catalyzed Chemoselective Methylation of Phenols and Thiophenols with Dimethyl Carbonate, Tetrahedron Lett.54, 7167-7170, 2013.
  52. Gao X., Chen L., Xie J., Yin Y., Chang T., Duan Y., and Jiang N., In Vitro Controlled Release of Vitamin C from Ca/Al Layered Double Hydroxide Drug Delivery System, Mater. Sci. Eng. C39, 56-60, 2014.
  53. Megalathan A., Kumarage S., Dilhari A., Weerasekera M.M., Samarasinghe S., and Kottegoda N., Natural Curcuminoids Encapsulated in Layered Double Hydroxides: A Novel Antimicrobial Nanohybrid, Chem. Cent. J.10, 35, 2016.
  54. Zhao S., Xu J., Wei M., and Song Y.F., Synergistic Catalysis by Polyoxometalate-Intercalated Layered Double Hydroxides: Oximation of Aromatic Aldehydes with Large Enhancement of Selectivity, Green Chem.13, 384-389, 2011.
  55. Chowdhury P.R., and Bhattacharyya K.G., Ni/Ti Layered Double Hydroxide: Synthesis, Characterization and Application as a Photocatalyst for Visible Light Degradation of Aqueous Methylene Blue, Dalton Trans.44, 6809-6824, 2015.
  56. Xie L.J., Sun G.H., Xie L.F., Su F.Y., Li X.M., Liu Z., and Chen C.M., A High Energy Density Asymmetric Supercapacitor Based on a CoNi-Layered Double Hydroxide and Activated Carbon, New Carbon Mater.31, 37-45, 2016.
  57. Kameda T., Tochinai M., Kumagai S., and Yoshioka T., Treatment of HCl Gas by Cyclic Use of Mg-Al Layered Double Hydroxide Intercalated with CO32-Atmos. Pollut. Res., 11, 290-295, 2020.
  58. Liu J., Chen G., and Yang J., Preparation and Characterization of Poly(vinyl chloride)/Layered Double Hydroxide Nanocomposites with Enhanced Thermal Stability, Polymer, 49, 3923-3927, 2008.
  59. Kalali E.N., Wang X., and Wang D.Y., Multifunctional Intercalation in Layered Double Hydroxide: Toward Multifunctional Nanohybrids for Epoxy Resin, J. Mater. Chem. A, 4, 2147-2157, 2016.
  60. Chakraborti M., Jackson J.K., Plackett D., Gilchrist S.E., and Burt H.M., The Application of Layered Double Hydroxide Clay (LDH)-Poly(lactide-co-glycolic acid)(PLGA) Film Composites for the Controlled Release of Antibiotics, J. Mater. Sci. Mater. M, 23, 1705-1713, 2012.
  61. Sharmin E. and Zafar F., Polyurethane: an Introduction, Polyurethane, InTech, 3-16, 2012.
  62. Mohammadi A., Barikani M., and Barmar M., Synthesis and Investigation of Thermal and Mechanical Properties of in Situ Prepared Biocompatible Fe3O4/Polyurethane Elastomer Nanocomposites, Polym. Bull., 72, 219-234, 2015.
  63. Mohammadi A., Barikani M., and Barmar M., Effect of Polyol Structure on the Properties of the Resultant Magnetic Polyurethane Elastomer Nanocomposites, Polym. Adv. Technol., 24, 978-985, 2013.
  64. Hepburn C., Polyurethane Elastomers, Springer Science and Business Media, 1-7, 2012. 
  65. Saunders K.J., Polyurethanes, Organic Polymer Chemistry, Springer, Dordrecht, 358-387, 1988.
  66. Younas M., Noreen A., Sharif A., Majeed A., Hssan A., Tabasum S., and Zia K.M., A Review on Versatile Applications of Blends and Composites of CNC with Natural and Synthetic Polymers with Mathematical Modeling,  Int. J. Biol. Macromol., 120, 603-632, 2018.
  67. Mohammadi A., Lakouraj M.M., and Barikani M., Preparation and Characterization of p-tert-Butyl Thiacalix [4] Arene Imbedded Flexible Polyurethane Foam: an Efficient Novel Cationic Dye Adsorbent, React. Funct. Polym.83, 14-23, 2014.
  68. Xie F., Zhang T., Bryant P., Kurusingal V., Colwell J.M., and Laycock B., Degradation and Stabilization of Polyurethane Elastomers, Prog. Polym. Sci.90, 211-268, 2019.
  69. Xu W.Z., Wang S.Q., Liu L., and Hu Y., Synthesis of Heptamolybdate-Intercalated MgAl LDHs and Its Application in Polyurethane Elastomer, Polym. Adv. Technol.27, 250-257, 2016.
  70. Heath D.E., Guelcher S.A., and Cooper S.L., Polyurethanes, Biomaterials Science, Elsevier, The Netherland, Sci., 103-108, 2020.
  71. Honarkar H., Waterborne Polyurethanes: A Review, J. Disper Sci. Technol.39, 507-516, 2018.
  72. Zafar F., Ghosal A., Sharmin E., Chaturvedi R., and Nishat N., A Review on Cleaner Production of Polymeric and Nanocomposite Coatings Based on Waterborne Polyurethane Dispersions from Seed Oils, Prog. Org. Coat.131, 259-275, 2019.
  73. Thomas S., Datta J., Haponiuk J., and Reghunadhan A., Polyurethane Polymers: Composites and Nanocomposites, Elsevier, 2017. 
  74. Vaithylingam R., Ansari M.N.M., and Shanks R.A., Recent Advances in Polyurethane-based Nanocomposites: A Review, Polym. Plast. Technol.56, 1528-1541, 2017.
  75. Yang Y.H., Li Y.C., Shields J., and Davis R.D., Layer Double Hydroxide and Sodium Montmorillonite Multilayer Coatings for the Flammability Reduction of Flexible Polyurethane Foams, J. Appl. Polym. Sci.132, 41767, 2015.
  76. Gao L., Zheng G., Zhou Y., Hu L., Feng G., and Xie Y., Synergistic Effect of Expandable Graphite, Melamine Polyphosphate and Layered Double Hydroxide on Improving the Fire Behavior of Rosin-Based Rigid Polyurethane Foam, Ind. Crop Prod.50, 638-647, 2013.
  77. Morioka H., Tagaya H., Karasu M., Kadokawa J., and Chiba K., Preparation of New Useful Materials by Surface Modification of Inorganic Layered Compound. J. Solid State Chem., 117, 337-342, 1995.
  78. Zhang C., Yu J., Feng K., Xue L., and Xie D., Synthesis and Characterization of Triethoxyvinylsilane Surface Modified Layered Double Hydroxides and Application in Improving UV Aging Resistance of Bitumen, Appl. Clay Sci.120, 1-8, 2016.
  79. Hu H., Yuan Y., and Shi W., Preparation of Waterborne Hyperbranched Polyurethane Acrylate/LDH Nanocomposite, Prog. Org. Coat.75, 474-479, 2012.
  80. Kotal M. and Srivastava S.K., Synergistic Effect of Organo Modification and Isocyanate Grafting of Layered Double Hydroxide in Reinforcing Properties of Polyurethane Nanocomposites, J. Mater. Chem.21, 18540-18551, 2011.
  81. Phua S. L., Yang L., Huang S., Ding G., Zhou R., Lew J. H., and Lu X., Shape Memory Polyurethane with Polydopamine-Coated Nanosheets: Simultaneous Enhancement of Recovery Stress and Strain Recovery Ratio and the Underlying Mechanisms, Eur. Polym. J., 57, 11-21, 2014.
  82. Kotal M., Kuila T., Srivastava S.K., and Bhowmick A.K., Synthesis and Characterization of Polyurethane/Mg-Al Layered Double Hydroxide Nanocomposites, J. Appl. Polym. Sci., 114, 2691-2699, 2009.
  83. Guo S., Zhang C., Peng H., Wang W., and Liu T., Structural Characterization, Thermal and Mechanical Properties of Polyurethane/CoAl Layered Double Hydroxide Nanocomposites Prepared via in Situ Polymerization, Compos. Sci. Technol., 71, 791-796. 2011.
  84. Kotal M., Srivastava S.K., Bhowmick A.K., and Chakraborty S.K., Morphology and Properties of Stearate-Intercalated Layered Double Hydroxide Nanoplatelet-Reinforced Thermoplastic Polyurethane, Polym. Int.60, 772-780, 2011.
  85. Shanmuganathan K. and Ellison C.J., Layered Double Hydroxides: An Emerging Class of Flame Retardants, Polymer Green Flame Retardants, 675-707, 2014.
  86. Mohammadi A., Wang D.Y., Hosseini A.S., and De La Vega J., Effect of Intercalation of Layered Double Hydroxides with Sulfonate-Containing Calix[4]arenes on the Flame Retardancy of Castor Oil-Based Flexible Polyurethane Foams, Polym. Test.79, 106055, 2019.
  87. Xu W., Xu B., Li A., Wang X., and Wang G., Flame Retardancy and Smoke Suppression of MgAl Layered Double Hydroxides Containing P and Si in Polyurethane Elastomer, Ind. Eng. Chem. Res.55, 11175-11185, 2016.
  88. Chen H.-B., Shen P., Chen M.J., Zhao H.B., and Schiraldi D.A., Highly Efficient Flame Retardant Polyurethane Foam with Alginate/Clay Aerogel Coating, ACS Appl. Mater. Interfaces, 8, 32557-32564, 2016.
  89. Gómez-Fernández S., Ugarte L., Peña-Rodriguez C., Corcuera M.A., and Eceiza A., The Effect of Phosphorus Containing Polyol and Layered Double Hydroxides on the Properties of a Castor Oil Based Flexible Polyurethane Foam, Polym. Degrad. Stab.132, 41-51, 2016.
  90. Li B., He J., Evans D.G., and Duan X., Inorganic Layered Double Hydroxides as a Drug Delivery System-Intercalation and In Vitro Release of Fenbufen, Appl. Clay Sci27, 199-207, 2004.
  91. Yang Y., Xiong L., Huang X., Shi Q., and Zhang W.D., Waterborne Polyurethane Composites with Antibacterial Activity by Incorporating p-BzOH Intercalated MgAl-LDH, Compos. Commun., 13, 112-118, 2019.
  92. Xie H., Ye Q., Si J., Yang W., Lu H., and Zhang Q., Synthesis of a Carbon Nanotubes/ZnAl-Layered Double Hydroxide Composite as a Novel Flame Retardant for Flexible Polyurethane Foams, Polym. Adv. Technol.27, 651-656, 2016.
  93. Xiong L., Zhang W.D., Shi Q.S., and Mai A.P., Waterborne Polyurethane/NiAl-LDH/ZnO Composites with High Antibacterial Activity, Polym. Adv. Technol., 26, 495-501, 2015.
  94. Kotal M., Srivastava S.K., and Bhowmick A.K., Thermoplastic Polyurethane and Nitrile Butadiene Rubber Blends with Layered Double Hydroxide Nanocomposites by Solution Blending, Polym. Int.59, 2-10, 2010.
  95. Roy S., Srivastava S. K., and Mittal V., Facile Noncovalent Assembly of MWCNT-LDH and CNF-LDH as Reinforcing Hybrid Fillers in Thermoplastic Polyurethane/Nitrile Butadiene Rubber Blends, J Polym Res23, 36, 2016.
  96. Dutta J., Chatterjee T., and Naskar K., LDH as a Multifunctional Additive in EVA/TPU Blends: Influence on Mechanical, Thermal, Rheological and Flame Retardancy Properties, Mat. Sci. Eng. B, 236, 84-94, 2018.
  97. Roy S., Srivastava S.K., Pionteck J., and Mittal V., Assembly of Layered Double Hydroxide on Multi-Walled Carbon Nanotubes as Reinforcing Hybrid Nanofiller in Thermoplastic Polyurethane/Nitrile Butadiene Rubber Blends, Polym. Int., 65, 93-101, 2016.