Dimensions of Biological Cellulose Nanocrystals Maximize Fracture Strength

详细信息    查看全文

• 作者：Robert Sinko ; Shawn Mishra ; Luis Ruiz ; Nick Brandis ; Sinan Keten
• 刊名：ACS Macro Letters
• 出版年：2014
• 出版时间：January 21, 2014
• 年：2014
• 卷：3
• 期：1
• 页码：64-69
• 全文大小：356K
• ISSN：2161-1653

文摘

Cellulose nanocrystals (CNCs) exhibit outstanding mechanical properties exceeding that of Kevlar, serving as reinforcing domains in nature鈥檚 toughest biological nanocomposites such as wood. To establish a molecular-level understanding of how CNCs develop high resistance to failure, here we present new analyses based on atomistic simulations on the fracture energy of I尾 CNCs. We show that the fracture energy depends on the crystal width, due to edge defects that significantly reduce the fracture energy of small crystals but have a negligible effect beyond a critical width. Additionally, collective effects of sheet stacking and stabilization by van der Waals interactions saturate at a critical crystal thickness that we predict with an analytical relationship based on a physical model. Remarkably, ideal dimensions optimizing fracture energy are found to be 4.8鈥?.6 nm in thickness (approximately 6鈥? layers) and 6.2鈥?.3 nm in width (approximately 6鈥? cellulose chains), which correspond to the common dimensions of CNCs found in nature. Our studies shed light on evolutionary principles that provide guidance toward high mechanical performance in natural and synthetic nanobiocomposites.