Viscoelasticity and Structures in Chemically and Physically Dual-Cross-Linked Hydrogels: Insights from Rheology and Proton Multiple-Quantum NMR Spectroscopy
Viscoelasticity and Structures in Chemically and Physically Dual-Cross-Linked Hydrogels: Insights from Rheology and Proton Multiple-Quantum NMR Spectroscopy
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化学和物理双交联水凝胶的粘弹性和结构：来自流变学和质子多量子核磁共振波谱的见解
DOI：
10.1021/acs.macromol.7b01854
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发表时间：
2017-12-12
期刊：
影响因子：
5.5
通讯作者：
Sun, Pingchuan
中科院分区：
文献类型：
--
作者：
Zou, Xueting;Kui, Xing;Sun, Pingchuan
水凝胶作为一种新型材料，由于其在各个领域的广泛应用而受到了广泛的关注。作为一种柔软和潮湿的材料，其力学行为最好理解为对周期性变形的粘弹性响应，这与微观化学/物理交联结构密切相关。本文通过流变学和质子多量子（MQ）NMR光谱详细研究了双交联（DC）水凝胶，其中通过离子配位（Fe 3+）的物理交联网络施加在化学交联的聚（丙烯酰胺-共-丙烯酸）网络上。流变学实验揭示了DC水凝胶由动态Fe 3+配位相互作用诱导的不同的温度和应变频率依赖性粘弹行为，与单一化学交联（SC）水凝胶相反。在剪切过程中，具有中等或弱结合强度的三价Fe ~（3+）配合物可能转变为具有强结合强度的三价Fe ~（3+）配合物。
Hydrogels have received considerable attention as an innovative material due to their widespread applications in various fields. As a soft and wet material, its mechanical behavior is best understood in terms of the viscoelastic response to the periodic deformation, which is closely related to the microscopic chemically/physically cross-linked structures. Herein, a dual-cross-linked (DC) hydrogel, where a physically cross-linked network by ionic coordination (Fe3+) is imposed on a chemically cross-linked poly(acrylamide-co-acrylic acid) network, was studied in detail by rheology and proton multiple-quantum (MQ) NMR spectroscopy. Rheology experiments revealed the diverse temperature- and strain-frequency-dependent viscoelastic behaviors for DC hydrogels induced by the dynamic Fe3+ coordination interactions, in contrast to the single chemically cross-linked (SC) hydrogels. During the shear experiment, the trivalent Fe3+ complex with moderate/weak binding strength might transform to those with strong binding...