Dimensions of Biological Cellulose Nanocrystals Maximize Fracture Strength

Sinko, Robert; Mishra, Shawn; Ruiz, Luis; Brandis, Nick; Keten, Sinan

doi:10.1021/mz400471y

Cited by 69 publications

(69 citation statements)

References 59 publications

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“…The ideal size predicted from simulation is in good agreement with the observed size in natural systems (Fig. 3d) 50 , suggesting that their size is optimized to resist both interfacial failure and crystal breaking. These results are also relevant to the development of synthetic polymer-CNC nanocomposites, as they provide guidance towards choosing an appropriate size CNC to use as filler material to optimize performance.…”

Section: Multiscale and Multiphasic Organizationsupporting

confidence: 75%

“…To help explain this small size of CNCs observed in natural systems, molecular simulations were conducted and have shown that the energy required to fracture a single CNC reaches an asymptotic value at a relatively short length scale of a few nanometres (Fig. 3c) 50 . However, the size of these crystals within composites such as wood must also maximize the surface-area-to-volume ratio to prevent failure at interfaces of amorphous and crystalline domains.…”

Section: Multiscale and Multiphasic Organizationmentioning

confidence: 99%

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The role of mechanics in biological and bio-inspired systems

et al. 2015

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Natural systems frequently exploit intricate multiscale and multiphasic structures to achieve functionalities beyond those of man-made systems. Although understanding the chemical make-up of these systems is essential, the passive and active mechanics within biological systems are crucial when considering the many natural systems that achieve advanced properties, such as high strength-to-weight ratios and stimuli-responsive adaptability. Discovering how and why biological systems attain these desirable mechanical functionalities often reveals principles that inform new synthetic designs based on biological systems. Such approaches have traditionally found success in medical applications, and are now informing breakthroughs in diverse frontiers of science and engineering. N atural biological systems are constrained by a limited number of chemical building blocks, yet through practical material organization and mechanics 1 , fulfil the functional needs of diverse organisms by methods that often exceed what is currently achievable using man-made approaches 2 . Synthetic systems are often limited by trade-offs where improving one property comes at the expense of another, as observed when utilizing ceramics in place of metals where a higher elastic modulus is accompanied by lower fracture toughness. However, many natural systems and materials have evolved 3 solutions that result in a number of improved properties simultaneously (for example, high modulus with high fracture toughness), and often produce systems that fulfil multiple functions concurrently. For example, stomatopod dactyl clubs 4 tolerate exceptional amounts of damage through multiphasic material interfaces, and efficient blood-clotting mechanisms are achieved through platelet shape adaptability 5 . These intricate mechanics phenomena, relating material organization and adaptability, are implemented in a structurally minimalistic fashion that is difficult to emulate through artificial manufacturing approaches 6 . Such mechanical functions (that is, mechanofunctionality) of biological systems are not isolated cases-multiscale structural organization also contributes to the hardness of nacre 7 and toughness of toucan beaks 8 , while shape changing commonly drives behaviour in many sea creatures 9 and plants 10 . As such recurrent, mechanically based organizational features throughout biology are discovered and analysed, they provide insight for building exceptional mechanofunctionalities into synthetic, bio-inspired technologies.The survival of organisms is often heightened by structures and materials with favourable properties (for example, load-bearing capacity) or mechanofunctionalities that are passive

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Section: Multiscale and Multiphasic Organizationsupporting

confidence: 75%

Section: Multiscale and Multiphasic Organizationmentioning

confidence: 99%

The role of mechanics in biological and bio-inspired systems

et al. 2015

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“…Through a combination of computational (Dri et al, 2013;Kulasinski et al, 2014;Sinko et al, 2014;Wu et al, 2013) and experimental (Kong and Eichhorn, 2005;Lindman et al, 2010;Nishiyama et al, 2002;Tashiro and Kobayashi, 1991) studies, it has been established that both hydrogen bonding and secondary van der Waals interactions play a crucial role in determining the emergent macroscale properties of these crystals. For Iβ cellulose, commonly called "natural" cellulose, it has been shown that hydrogen bonding is dominant along the (110) plane while van der Waals interactions are dominant along the (200) plane (Sinko et al, 2014), with these planes indicated in Figure 1A.…”

Section: Introductionmentioning

confidence: 99%

Traction–separation laws and stick–slip shear phenomenon of interfaces between cellulose nanocrystals

Sinko

Keten

2015

Journal of the Mechanics and Physics of Solids

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Cellulose nanocrystals (CNCs) are one of nature's most abundant structural material building blocks and possess outstanding mechanical properties such as a tensile modulus comparable to Kevlar. It remains challenging to upscale these properties in CNC neat films and nanocomposites due to the difficulty of characterizing interfacial bonding between CNCs that govern stress transfer under deformation. Here we present new analyses based on atomistic simulations of shear and tensile failure of the interfaces between Iβ CNCs in elementary fibrils, providing new insight into factors governing the mechanical behavior of hierarchical nanocellulose materials. We compare the two most relevant crystal surfaces and find that hydrogen bonded surfaces have greater tensile strength compared to the surfaces governed by weaker interactions. On the contrary, shearing simulations show that friction between the atomic interfaces depends not only on surface energy but also the energy landscape along the shear direction. While being a weaker interface, the intersheet plane exhibits greater energy barriers to shear. The molecular roughness of this interface, characterized by a greater energy barrier, exhibits a stick-slip deformation behavior as opposed to a continuous sliding mechanism observed for the interfaces with hydrogen bonds. Analytical models to describe the energy landscapes are developed using energy scaling relations for van der Waals surfaces in combination with a modification of the Prandtl-Tomlinson model for atomic friction. Our simulations pave the way for tailoring hierarchical CNC materials by taking a similar approach to techniques employed for describing metals, where mechanical properties can be tuned through a deeper understanding of grain boundary physics and nanoscale interfaces. 3 Graphical Abstract: 4

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“…73 MD simulation showed in Ib crystalline cellulose that elastic modulus, Poisson's ratio, yield stress and strain, and ultimate stress and strain are highly anisotropic, and that although properties that describe elastic behavior of the material are independent of strain rate, yield and ultimate properties increase with increasing strain rate. 74 In another MD study, 75 the fracture energy of crystalline cellulose was found to depend on crystal width, due to edge defects that significantly reduce the fracture energy of small crystals but have a negligible effect beyond a critical width. Remarkably, ideal dimensions optimizing fracture energy are found to be similar to the common dimensions of crystalline nanocellulose found in nature, suggesting a natural optimization of structure.…”

Section: Applications Of Atomistic Simulations In Understanding Smallmentioning

confidence: 99%

Not Just Lumber—Using Wood in the Sustainable Future of Materials, Chemicals, and Fuels

Jakes

Arzola-Villegas

Bergman

et al. 2016

JOM

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Forest-derived biomaterials can play an integral role in a sustainable and renewable future. Research across a range of disciplines is required to develop the knowledge necessary to overcome the challenges of incorporating more renewable forest resources in materials, chemicals, and fuels. We focus on wood specifically because in our view, better characterization of wood as a raw material and as a feedstock will lead to its increased utilization. We first give an overview of wood structure and chemical composition and then highlight current topics in forest products research, including (1) industrial chemicals, biofuels, and energy from woody materials; (2) wood-based activated carbon and carbon nanostructures; (3) development of improved wood protection treatments; (4) massive timber construction; (5) wood as a bioinspiring material; and (6) atomic simulations of wood polymers. We conclude with a discussion of the sustainability of wood as a renewable forest resource. WOOD'S 390 MILLIONTH BIRTHDAYWood is one of the major innovations of land plants ''invented'' some 390 million years ago. Wood enabled individual plants to increase their stature and persistence in the environment, facilitating the ability of trees to play roles in landscape change and biome composition and to fundamentally alter the global cycling of water, minerals, and carbon. Since prehistoric times, humans have found wood invaluable for meeting many of their needs, including energy, tools, and shelter-not surprising given its near-ubiquity, versatility, and renewability. Only in the comparatively recent past have other nonrenewable natural resources, such as fossil fuels or metal ores, become the resources of choice to meet our material needs. We postulate that wood will play an increasing role in the sustainability of our future materials through both expansion of uses for current forest products and development of alternatives to materials currently derived from nonrenewable resources. Life cycle assessments, which categorize energy consumption and emission profiles for products over their whole life cycle, 1,2 consistently show that many wood-based materials use less fossil fuels to produce than do competing materials.3,4 Using wood products can also lower atmospheric carbon dioxide levels because growing forests capture carbon and harvested wood products store the accumulated carbon while in service.Historically, wood research has been the purview of wood technologists; however, we see the future of wood research as interdisciplinary, collaborative, quantitative, and meaningful, both scientifically

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Dimensions of Biological Cellulose Nanocrystals Maximize Fracture Strength

Cited by 69 publications

References 59 publications

The role of mechanics in biological and bio-inspired systems

The role of mechanics in biological and bio-inspired systems

Traction–separation laws and stick–slip shear phenomenon of interfaces between cellulose nanocrystals

Not Just Lumber—Using Wood in the Sustainable Future of Materials, Chemicals, and Fuels

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