High Fracture Efficiency and Stress Concentration Phenomenon for Microgel-Reinforced Hydrogels Based on Double-Network Principle
High Fracture Efficiency and Stress Concentration Phenomenon for Microgel-Reinforced Hydrogels Based on Double-Network Principle
复制标题
DOI：
10.1021/ma301933x
复制
发表时间：
2012-12-11
期刊：
影响因子：
5.5
通讯作者：
Gong, Jian Ping
中科院分区：
文献类型：
--
作者：
Hu, Jian;Kurokawa, Takayuki;Gong, Jian Ping
双网络水凝胶因其优异的机械强度和韧性、低滑动摩擦、良好的生物相容性以及组分的广泛可调性而引起了人们的极大兴趣。通过对凝胶的重新审视，我们提供了一种巧妙的方法来制备一种强韧的微凝胶增强水凝胶(MR GELS)，将聚(2-丙烯酰胺基-2-甲基丙磺酸钠)(PNaAMPS)的稠交联聚电解质微凝胶(PNaAMPS)(取代了传统DN凝胶的稠交联聚NaAMPS宏观网络)引入稀疏交联中性聚丙烯酰胺(PAAM)基质中。磁流变凝胶的结构可以看作是一种两相复合材料，其中分散相为刚性的DN微凝胶，连续相为软的PAAM基质。与DN凝胶类似，MR凝胶在磁滞测量中表现出不可逆的能量耗散，表明脆性PNaAMPS相的永久断裂。因此，不连续的脆性相也是牺牲键。通过对磁致伸缩凝胶的滞回曲线和实时拉伸过程中嵌入微凝胶的形态变化进行定量比较，我们得出结论：由于微凝胶周围的应力集中，在相同应变下，磁致伸缩微凝胶中牺牲键的断裂效率是普通凝胶的4倍。
Double-network hydrogels (DN gels) have aroused considerable interest because of their excellent mechanical strength and toughness, low sliding friction, good biocompatibility, as well as wide tunability in components. By revisiting DN gels, we provide an ingenious way to fabricate a kind of strong and tough microgel-reinforced hydrogels (MR gels), that densely cross-linked polyelectrolyte microgels of poly(2-acrylamido-2-methylpropanesulfonic sodium) (PNaAMPS) (replacing the densely crosslinked PNaAMPS macro-network for conventional DN gels) are incorporated into sparsely cross-linked neutral polyacrylamide (PAAm) matrix. The structure of MR gels can be considered as a two-phase composite, where the disperse phase is the rigid DN microgels, and the continuous phase is the soft PAAm matrix. Similar to DN gels, MR gels show the irreversible energy dissipation in the hysteresis measurement, demonstrating the permanent fracture of the brittle PNaAMPS phase. Thus, the discontinuous brittle phase also serves as sacrificial bonds. Through quantitative comparison of the hysteresis curves with DN gels and monitoring the morphology change of the embedded microgels in MR gels during the real-time stretching process, we conclude that the DN microgels in MR gels show four times higher in fracture efficiency of the sacrificial bonds than bulk DN gels at the same strain, as a result of the stress concentration around the microgels.