Abstract
Due to their exceptional mechanical and chemical properties and their natural abundance, cellulose nanocrystals (CNCs) are promising building blocks of sustainable polymer composites. However, the rapid gelation of CNC dispersions has generally limited CNC-based composites to low CNC fractions, in which polymer remains the dominant phase. Here we report on the formulation and processing of crosslinked CNC-epoxy composites with a CNC fraction exceeding 50 wt%. The microstructure comprises sub-micrometer aggregates of CNCs crosslinked to polymer, which is analogous to the lamellar structure of nacre and promotes toughening mechanisms associated with bulk ductility, despite the brittle behavior of the aggregates at the nanoscale. At 63 wt% CNCs, the composites exhibit a hardness of 0.66 GPa and a fracture toughness of 5.2 MPa m\(^{1/2}\). The hardness of this all-organic material is comparable to aluminum alloys, and the fracture toughness at the centimeter scale is comparable to that of wood cell walls. We show that 3D CNC-epoxy composite objects can be shaped from the gel precursors by direct-write printing, casting, and machining. The formulation, processing route, and insights on toughening mechanisms gained from our multiscale approach can be applied broadly to highly loaded nanocomposites.
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Abitbol T, Cranston ED (2014) Chiral nematic self-assembly of cellulose nanocrystals in suspensions and solid films. In: Handbook of green materials, world scientific, pp 37–56. https://doi.org/10.1142/9789814566469_0035
Adler DC, Buehler MJ (2013) Mesoscale mechanics of wood cell walls under axial strain. Soft Matter 9(29):7138. https://doi.org/10.1039/c3sm50183c
Akono AT, Ulm FJ (2014) An improved technique for characterizing the fracture toughness via scratch test experiments. Wear 313(1–2):117–124. https://doi.org/10.1016/j.wear.2014.02.015
Akono AT, Reis PM, Ulm FJ (2011) Scratching as a fracture process: from butter to steel. Phys Rev Lett 106(20):204302. https://doi.org/10.1103/PhysRevLett.106.204302
Akono AT, Randall NX, Ulm FJ (2012) Experimental determination of the fracture toughness via microscratch tests: application to polymers, ceramics, and metals. J Mater Res 27(02):485–493. https://doi.org/10.1557/jmr.2011.402
Allen M, Poggiali D, Whitaker K, Marshall TR, Kievit R (2018) Raincloud plots: a multi-platform tool for robust data visualization. Peer J 6:e27137v1 (Preprints). https://doi.org/10.7287/peerj.preprints.27137v1
Ashby MF (2011) Material property charts. In: Materials selection in mechanical design. Butterworth-Heinemann, Oxford, pp 57–96. https://doi.org/10.1016/B978-1-85617-663-7.00004-7
Barthelat F, Li CM, Comi C, Espinosa HD (2006) Mechanical properties of nacre constituents and their impact on mechanical performance. J Mater Res 21(8):1977–1986. https://doi.org/10.1557/jmr.2006.0239
Barthelat F, Yin Z, Buehler MJ (2016) Structure and mechanics of interfaces in biological materials. Nat Rev Mater 1(4):16007. https://doi.org/10.1038/natrevmats.2016.7
Borodich FM, Bull SJ, Epshtein SA (2015) Nanoindentation in studying mechanical properties of heterogeneous materials. J Min Sci 51(3):470–476. https://doi.org/10.1134/S1062739115030072
Bouville F, Maire E, Meille S, Van de Moortèle B, Stevenson AJ, Deville S, de Moortèle B, Stevenson AJ, Deville S (2014) Strong, tough and stiff bioinspired ceramics from brittle constituents. Nat Mater 13(5):508–514. https://doi.org/10.1038/nmat3915
Briscoe BJ, Fiori L, Pelillo E (1998) Nano-indentation of polymeric surfaces. J Phys D Appl Phys 31(19):2395–2405. https://doi.org/10.1088/0022-3727/31/19/006
Bruet B, Qi H, Boyce M, Panas R, Tai K, Frick L, Ortiz C (2005) Nanoscale morphology and indentation of individual nacre tablets from the gastropod mollusc trochus niloticus. J Mater Res 20(9):2400–2419. https://doi.org/10.1557/jmr.2005.0273
Constantinides G, Ravi Chandran KS, Ulm FJ, Van Vliet KJ (2006) Grid indentation analysis of composite microstructure and mechanics: principles and validation. Mater Sci Eng A 430(1–2):189–202. https://doi.org/10.1016/j.msea.2006.05.125
Cook RF, Pharr GM (1990) Direct observation and analysis of indentation cracking in glasses and ceramics. J Am Ceram Soc 73(4):787–817. https://doi.org/10.1111/j.1151-2916.1990.tb05119.x
Dunlop JWC, Fratzl P (2010) Biological composites. Annu Rev Mater Res 40(1):1–24. https://doi.org/10.1146/annurev-matsci-070909-104421
Dunlop JWC, Weinkamer R, Fratzl P (2011) Artful interfaces within biological materials. Mater Today 14(3):70–78. https://doi.org/10.1016/S1369-7021(11)70056-6
Gao HL, Chen SM, Mao LB, Song ZQ, Yao HB, Cölfen H, Luo XS, Zhang F, Pan Z, Meng YF, Ni Y, Yu SH (2017) Mass production of bulk artificial nacre with excellent mechanical properties. Nat Commun 8(1):287. https://doi.org/10.1038/s41467-017-00392-z
George J, Sabapathi SN (2015) Cellulose nanocrystals: synthesis, functional properties, and applications. Nanotechnol Sci Appl 45. https://doi.org/10.2147/NSA.S64386
Gray D, Mu X (2015) Chiral nematic structure of cellulose nanocrystal suspensions and films; polarized light and atomic force microscopy. Materials 8(12):7873–7888. https://doi.org/10.3390/ma8115427
Gu GX, Libonati F, Wettermark SD, Buehler MJ (2017) Printing nature: unraveling the role of nacre’s mineral bridges. J Mech Behav Biomed Mater 76:135–144. https://doi.org/10.1016/j.jmbbm.2017.05.007
Habibi Y, Lucia LA, Rojas OJ (2010) Cellulose nanocrystals: chemistry, self-assembly, and applications. Chem Rev 110(6):3479–3500. https://doi.org/10.1021/cr900339w
Hon DNS (1994) Cellulose: a random walk along its historical path. Cellulose 1(1):1–25. https://doi.org/10.1007/BF00818796
Imbeni V, Kruzic JJ, Marshall GW, Marshall SJ, Ritchie RO (2005) The dentin-enamel junction and the fracture of human teeth. Nat Mater 4(3):229–232. https://doi.org/10.1038/nmat1323
Jiang H, Browning R, Sue HJ (2009) Understanding of scratch-induced damage mechanisms in polymers. Polymer 50(16):4056–4065. https://doi.org/10.1016/j.polymer.2009.06.061
Khelifa F, Habibi Y, Bonnaud L, Dubois P (2016) Epoxy monomers cured by high cellulosic nanocrystal loading. ACS Appl Mater Interf 8(16):10535–10544. https://doi.org/10.1021/acsami.6b02013
Kim HJ, Park S, Kim SH, Kim JH, Yu H, Kim HJ, Yang YH, Kan E, Kim YH, Lee SH (2015) Biocompatible cellulose nanocrystals as supports to immobilize lipase. J Mol Catal B Enzym 122:170–178. https://doi.org/10.1016/j.molcatb.2015.09.007
Klemm D, Kramer F, Moritz S, Lindström T, Ankerfors M, Gray D, Dorris A (2011) Nanocelluloses: a new family of nature-based materials. Angew Chem Int Ed 50(24):5438–5466. https://doi.org/10.1002/anie.201001273
Kretschmann D (2003) Velcro mechanics in wood. Nat Mater 2(12):775–776. https://doi.org/10.1038/nmat1025
Kushch VI, Dub SN, Shmegera RS, Sirota YV, Tolmacheva GN (2015) Procedure of the multiple indentations for determination of the hardness parameters of structurally heterogeneous materials. J Superhard Mater 37(3):173–181. https://doi.org/10.3103/S1063457615030041
Lagerwall JPF, Schütz C, Salajkova M, Noh J, Hyun Park J, Scalia G, Bergström L (2014) Cellulose nanocrystal-based materials: from liquid crystal self-assembly and glass formation to multifunctional thin films. NPG Asia Mater 6(1):e80–e80. https://doi.org/10.1038/am.2013.69
Le Ferrand H, Bouville F, Niebel TP, Studart AR (2015) Magnetically assisted slip casting of bioinspired heterogeneous composites. Nat Mater 14(11):1172–1179. https://doi.org/10.1038/nmat4419
Li YQ, Yu T, Yang TY, Zheng LX, Liao K (2012) Bio-inspired nacre-like composite films based on graphene with superior mechanical, electrical, and biocompatible properties. Adv Mater 24(25):3426–3431. https://doi.org/10.1002/adma.201200452
Lichtenegger HC (2002) High Abrasion resistance with sparse mineralization: copper biomineral in worm jaws. Science 298(5592):389–392. https://doi.org/10.1126/science.1075433
Miller M, Bobko C, Vandamme M, Ulm FJ (2008) Surface roughness criteria for cement paste nanoindentation. Cem Concr Res 38(4):467–476. https://doi.org/10.1016/j.cemconres.2007.11.014
Moon RJ, Jakes JE, Beecher JF, Frihart CR, Stone DS (2009) Advanced biomass science and technology for bio-based products. In: Hse CY, Jiang Z, Kuo ML (eds) Relating nanoindentation to macroindentation of wood. Southern Research Station, Beijing, China, pp 145–159
Moon RJ, Martini A, Nairn J, Simonsen J, Youngblood J (2011) Cellulose nanomaterials review: structure, properties and nanocomposites. Chem Soc Rev 40(7):3941. https://doi.org/10.1039/c0cs00108b
Niebel TP, Bouville F, Kokkinis D, Studart AR (2016) Role of the polymer phase in the mechanics of nacre-like composites. J Mech Phys Solids 96:133–146. https://doi.org/10.1016/j.jmps.2016.06.011
Oliver WC, Pharr GM (1992) An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. J Mater Res 7(06):1564–1583. https://doi.org/10.1557/JMR.1992.1564
Paplham WP, Seferis JC, BaltáCalleja FJ, Zachmann HG (1995) Microhardness of carbon fiber reinforced epoxy and thermoplastic polyimide composites. Polym Compos 16(5):424–428. https://doi.org/10.1002/pc.750160512
Pharr GM, Herbert EG, Gao Y (2010) The indentation size effect: a critical examination of experimental observations and mechanistic interpretations. Annu Rev Mater Res 40(1):271–292. https://doi.org/10.1146/annurev-matsci-070909-104456
Pro JW, Barthelat F (2019) The fracture mechanics of biological and bioinspired materials. MRS Bull 44(1):46–52. https://doi.org/10.1557/mrs.2018.324
Pruksawan S, Samitsu S, Fujii Y, Torikai N, Naito M (2020) Toughening effect of rodlike cellulose nanocrystals in epoxy adhesive. ACS Appl Polymer Mater 2(3):1234–1243. https://doi.org/10.1021/acsapm.9b01102
Randall NX, Vandamme M, Ulm FJ (2009) Nanoindentation analysis as a two-dimensional tool for mapping the mechanical properties of complex surfaces. J Mater Res 24(03):679–690. https://doi.org/10.1557/jmr.2009.0149
Rao A, Divoux T, McKinley GH, Hart AJ (2019) Shear melting and recovery of crosslinkable cellulose nanocrystal-polymer gels. Soft Matter 15(21):4401–4412. https://doi.org/10.1039/C8SM02647E
Ritchie RO (2011) The conflicts between strength and toughness. Nat Mater 10(11):817–822. https://doi.org/10.1038/nmat3115
Schütz C, Agthe M, Fall AB, Gordeyeva K, Guccini V, Salajková M, Plivelic TS, Lagerwall JPF, Salazar-Alvarez G, Bergström L (2015) Rod packing in chiral nematic cellulose nanocrystal dispersions studied by small-angle x-ray scattering and laser diffraction. Langmuir 31(23):6507–6513. https://doi.org/10.1021/acs.langmuir.5b00924
Shell De Guzman M, Neubauer G, Flinn P, Nix WD (1993) The role of indentation depth on the measured hardness of materials. MRS Proc 308:613. https://doi.org/10.1557/PROC-308-613
Shen L, Phang IY, Liu T, Zeng K (2004) Nanoindentation and morphological studies on nylon 66/organoclay nanocomposites. II. Effect of strain rate. Polymer 45(24):8221–8229. https://doi.org/10.1016/j.polymer.2004.09.062
Siqueira G, Kokkinis D, Libanori R, Hausmann MK, Gladman AS, Neels A, Tingaut P, Zimmermann T, Lewis JA, Studart AR (2017) Cellulose nanocrystal inks for 3d printing of textured cellular architectures. Adv Funct Mater 1604619. https://doi.org/10.1002/adfm.201604619
Skrzypczak M, Guerret-Piecourt C, Bec S, Loubet JL, Guerret O (2009) Use of a nanoindentation fatigue test to characterize the ductile-brittle transition. J Eur Ceram Soc 29(6):1021–1028. https://doi.org/10.1016/j.jeurceramsoc.2008.07.066
Song J, Fan C, Ma H, Wei Y (2015) Hierarchical structure observation and nanoindentation size effect characterization for a limnetic shell. Acta Mech Sin 31(3):364–372. https://doi.org/10.1007/s10409-015-0405-x
Song J, Chen C, Zhu S, Zhu M, Dai J, Ray U, Li YY, Kuang Y, Li YY, Quispe N, Yao Y, Gong A, Leiste UH, Bruck HA, Zhu JY, Vellore A, Li H, Minus ML, Jia Z, Martini A, Li T, Hu L (2018) Processing bulk natural wood into a high-performance structural material. Nature 554(7691):224–228. https://doi.org/10.1038/nature25476
Staines M, Robinson WH, Hood JAA (1981) Spherical indentation of tooth enamel. J Mater Sci 16(9):2551–2556. https://doi.org/10.1007/BF01113595
Tesch W, Eidelman N, Roschger P, Goldenberg F, Klaushofer K, Fratzl P (2001) Graded microstructure and mechanical properties of human crown dentin. Calcif Tissue Int 69(3):147–157. https://doi.org/10.1007/s00223-001-2012-z
Tze W, Wang S, Rials T, Pharr G, Kelley S (2007) Nanoindentation of wood cell walls: continuous stiffness and hardness measurements. Compos A Appl Sci Manuf 38(3):945–953. https://doi.org/10.1016/j.compositesa.2006.06.018
Wang J, Shaw LL (2009) Nanocrystalline hydroxyapatite with simultaneous enhancements in hardness and toughness. Biomaterials 30(34):6565–6572. https://doi.org/10.1016/j.biomaterials.2009.08.048
Wegst UGK, Bai H, Saiz E, Tomsia AP, Ritchie RO (2015) Bioinspired structural materials. Nat Mater 14(1):23–36. https://doi.org/10.1038/nmat4089
Zhao H, Kwak J, Conradzhang Z, Brown H, Arey B, Holladay J (2007) Studying cellulose fiber structure by SEM, XRD, NMR and acid hydrolysis. Carbohyd Polym 68(2):235–241. https://doi.org/10.1016/j.carbpol.2006.12.013
Zhao H, Yang Z, Guo L (2018) Nacre-inspired composites with different macroscopic dimensions: strategies for improved mechanical performance and applications. NPG Asia Mater 10(4):1–22. https://doi.org/10.1038/s41427-018-0009-6
Acknowledgments
The authors thank Sooraj Narayan and Prof. Lallit Anand for assistance with the finite element model. Financial support was provided by the Procter and Gamble Corporation, and we thank Neville Sonnenberg for discussions related to the project. C.E.O. was supported by the United States Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.
Funding
Financial support was provided by the Procter and Gamble Corporation. C.E.O. was supported by the United States Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.
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AR and AJH conceived and designed the project, AR designed and performed the experiments and interpreted the data, TD supported the experiments and contributed to data interpretation, CEO designed the tooth model and performed the micromilling experiments. AJH supervised the research. AR, TD and AJH wrote the manuscript. All authors discussed the results and reviewed the manuscript.
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Rao, A., Divoux, T., Owens, C.E. et al. Printable, castable, nanocrystalline cellulose-epoxy composites exhibiting hierarchical nacre-like toughening. Cellulose 29, 2387–2398 (2022). https://doi.org/10.1007/s10570-021-04384-7
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DOI: https://doi.org/10.1007/s10570-021-04384-7