材料科学
自愈水凝胶
纳米复合材料
复合材料
极限抗拉强度
流变学
动态力学分析
各向同性
分子动力学
纳米颗粒
纳米晶
网络共价键合
共价键
聚合物
纳米技术
化学工程
高分子化学
化学
有机化学
计算化学
工程类
物理
量子力学
作者
Jun Yang,Chunrui Han,Feng Xu,Run‐Cang Sun
出处
期刊:Nanoscale
[The Royal Society of Chemistry]
日期:2014-01-01
卷期号:6 (11): 5934-5934
被引量:83
摘要
The physical crosslinking of colloidal nanoparticles via dynamic and directional non-covalent interactions has led to significant advances in composite hydrogels. In this paper, we report a simple approach to fabricate tough, stretchable and hysteretic isotropic nanocomposite hydrogels, where rod-like cellulose nanocrystals (CNCs) are encapsulated by flexible polymer chains of poly(N,N-dimethylacrylamide) (PDMA). The CNC–PDMA colloidal clusters build a homogeneously cross-linked network and lead to significant reinforcing effect of the composites. Hierarchically structured CNC–PDMA clusters, from isolated particles to an interpenetrated network, are observed by transmission electron microscopy measurements. Dynamic shear oscillation measurements are applied to demystify the differences in network rheological behaviors, which were compared with network behaviors of chemically cross-linked PDMA counterparts. Tensile tests indicate that the hybrid hydrogels possess higher mechanical properties and a more efficient energy dissipation mechanism. In particular, with only 0.8 wt% of CNC loading, a 4.8-fold increase in Young's modulus, 9.2-fold increase in tensile strength, and 5.8-fold increase in fracture strain are achieved, which is ascribed to a combination of CNC reinforcement in the soft matrix and CNC–PDMA colloidal cluster conformational rearrangement under stretching. Physical interactions within networks serve as reversible sacrificial bonds that dissociate upon deformation, exhibiting large hysteresis as an energy dissipation mechanism via cluster mobility. This result contrasts with the case of chemically cross-linked PDMA counterparts where the stress relaxation is slow due to the permanent cross-links and low resistance against crack propagation within the covalent network.
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