自愈水凝胶
形态学(生物学)
共价键
化学工程
水溶液中的金属离子
纤维素
金属
高分子化学
化学
有机化学
遗传学
生物
工程类
作者
Jun Yang,Feng Xu,Chunrui Han
出处
期刊:Biomacromolecules
[American Chemical Society]
日期:2017-02-13
卷期号:18 (3): 1019-1028
被引量:115
标识
DOI:10.1021/acs.biomac.6b01915
摘要
Utilization of reversible interactions as sacrificial bonds in biopolymers is critical for the integral synthesis of mechanically superior biological materials. In this work, cellulose nanofibrils (CNFs) reinforced covalent polyacrylamide (PAAm) composite hydrogels are immersed into multivalent cation (Ca2+, Zn2+, Al3+, and Ce3+) aqueous solution to form ionic association among CNFs, leading to the ionic-covalent cross-linked hydrogels. The cations promote the formation of porous networks of nanofibrils by screening the repulsive negative charges on CNF surface and dominate the mechanical properties and self-recovery efficiency of the hydrogels, resulting in mechanically reinforced ionic hydrogels with stiff (Young's modulus 257 kPa) and tough properties (fracture toughness 386 kJ/m3). The in situ Raman spectroscopy during stretching corroborates the stress transfer medium of CNF, and the microscopic morphologies of stable crack propagation validates that the multiple toughening mechanisms occur in a balanced energy dissipation manner, enabling synergistic combination of stiffness and toughness. Moreover, the depth-sensing instrumentation by indentation test also demonstrates that the CNF ionic coordination contributes simultaneous improvement in hardness and elasticity by as much as 600% compared to those pristine gels. This work demonstrates a facile way to transfer nanoscale building blocks to bulk elastomers with tunable dynamic properties and may provide a new prospect for the rational design of CNF reinforced hydrogels for applications where high-bearing capability is needed.
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