How can multi-bond network hydrogels dissipate energy more effectively: an investigation on the relationship between network structure and properties
How can multi-bond network hydrogels dissipate energy more effectively: an investigation on the relationship between network structure and properties
复制标题
多重键网络水凝胶如何更有效地耗能：网络结构与性能关系的研究
DOI：
10.1039/d0sm00455c
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发表时间：
2020
期刊：
影响因子：
3.4
通讯作者：
Xie Xu-Ming
中科院分区：
文献类型：
--
作者：
Xu Hao;Shi Fu-Kuan;Liu Xiao-Ying;Zhong Ming;Xie Xu-Ming
构建多键网络（MBN）是制备超韧性水凝胶的有效方法，该网络由具有不同键结合能的分层动态键组成。在这项工作中，少量的聚乙烯醇（PVA）被引入到一个松散的化学交联聚丙烯酸（PAA）网络。亲水性PVA链可与PAA链发生物理相互作用并形成氢键。经过冻融过程后，PVA部分结晶，生成的微晶可以成为水凝胶新的交联点。同时，PAA和PVA之间的氢键通过PVA链连接到微晶“核”上，也可以成为水凝胶新的交联点。所得三元交联水凝胶（t -凝胶10%）的韧性是纯PAA水凝胶的8倍。当PVA含量超过15 wt%时，PVA链将贯穿整个PAA网络。因此PVA链会通过冻融处理被微晶交联，形成双网络结构，形成脆性水凝胶。不同PVA含量的水凝胶的模量阶跃增加清楚地表明了水凝胶网络结构的变化。随后，将Fe3+作为第三个交联点引入MBN水凝胶中。得到的季铵盐交联水凝胶（q -凝胶10%-Fe5） （50 wt%含水量）的力学性能显著提高：抗拉强度高达6.83 MPa，断裂能为29.9 MJ m−3。这项工作为超韧MBN水凝胶的网络结构与力学性能之间的关系提供了清晰的见解。
Constructing a multi-bond network (MBN), which involves hierarchical dynamic bonds with different bond association energies, is an effective method for achieving super tough hydrogels. In this work, a small amount of poly(vinyl alcohol) (PVA) is introduced into a loosely chemically crosslinked poly(acrylic acid) (PAA) network. The hydrophilic PVA chains can physically interact and form hydrogen bonds with the PAA chains. After a freeze–thaw process, PVA could partially crystallize and the generated microcrystals could become new crosslinking points of the hydrogels. Meanwhile, the hydrogen bonds between PAA and PVA, which connect to the microcrystal “core” through PVA chains, could also become new crosslinking points of the hydrogels. The obtained ternary-crosslinked hydrogels (T-gel 10%) exhibit toughness as high as 8 times that in pure PAA hydrogels. When the PVA content exceeds 15 wt%, PVA chains will run through the whole PAA network. Thus the PVA chains will be crosslinked by microcrystals through freeze–thaw treatment, leading to a double network structure, resulting in a brittle hydrogel. The step-increased modulus of the hydrogels with different PVA contents clearly demonstrates the change in the network structure of the hydrogels. Successively, Fe3+ is introduced into the MBN hydrogels as a third cross-linking point. The obtained quaternary-crosslinked hydrogels (Q-gel 10%-Fe5) (50 wt% water content) exhibit significantly improved mechanical properties: tensile strength as high as 6.83 MPa with a fracture energy of 29.9 MJ m−3. This work provides clear insight into the relationship between network structure and mechanical properties in super tough MBN hydrogels.