Homogeneous and Real Super Tough Multi-Bond Network Hydrogels Created through a Controllable Metal Ion Permeation Strategy
Homogeneous and Real Super Tough Multi-Bond Network Hydrogels Created through a Controllable Metal Ion Permeation Strategy
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通过可控金属离子渗透策略创建均质且真正的超坚韧多键网络水凝胶
DOI：
10.1021/acsami.9b18620
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发表时间：
2019-11-13
影响因子：
9.5
通讯作者：
Xie, Xu-Ming
中科院分区：
文献类型：
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作者：
Liu, Xiao-Ying;Xu, Hao;Xie, Xu-Ming
利用柠檬酸铁(FECA)的可控渗透策略，制备了由稀疏的化学交联和羧基-Fe3+配位组成的多键网络的聚丙烯酸(PAA)水凝胶。现有的直接将PAA水凝胶浸泡在Fe3+溶液中的方法通常会导致水凝胶形成不均匀的网络，具有密集的交联壳和不确定的水含量，这给研究水凝胶的强化机理带来了不确定性，因为水含量对水凝胶的力学性能有很大的影响。其中，基于柠檬酸(CA)-Fe3+络合和PAA-Fe3+配位的竞争，Fe3+可控制地渗透到PAA网络中，保证了Fe3+的持续释放，促进了离子交联剂的均匀分布和一定的水分含量。所得水凝胶具有良好的平衡力学性能(当水含量从80%降至50wt%时，拉伸强度高达3.28~6.95 Mpa，断裂伸长率高达1400~780%)。这种水凝胶真正的强韧拉伸强度来自于均匀的PAA-Fe3+交联物的有效能量耗散，高含水量确保了较大的断裂伸长率。此外，该水凝胶还具有pH响应和形状记忆特性。
Poly(acrylic acid) (PAA) hydrogels with a multi-bond network composed of sparse chemical cross-links and carboxyl-Fe3+ coordination are prepared through a controllable permeation strategy utilizing ferric citrate (FeCA). The existing strategies that directly soak PAA hydrogels in Fe3+ solutions usually induce an inhomogeneous network with densely cross-linked shells and uncertain water content of the hydrogels, which brings about ambiguity when investigating strengthening mechanisms because water content significantly affects the mechanical properties of hydrogels. Herein, the controllable permeation of Fe3+ into PAA networks based on the competition between citric acid (CA)-Fe3+ chelation and PAA-Fe3+ coordination guarantees sustained release of Fe3+, facilitating homogeneous distribution of ionic cross-links and a certain water content. The obtained hydrogels exhibit excellent and balanced mechanical properties (high tensile strength of 3.28 to 6.95 MPa with large elongations at break of 1400 to 780% when water content decreases from 80 to 50 wt %). The real robust tensile strength of this hydrogel originates from the effective energy dissipation of the homogeneous PAA-Fe3+ cross-links, and the high water content ensures a large elongation at break. Furthermore, the hydrogel also has pH-responsive and shape-memory properties.