Effect of Structure Heterogeneity on Mechanical Performance of Physical Polyampholytes Hydrogels
Effect of Structure Heterogeneity on Mechanical Performance of Physical Polyampholytes Hydrogels
复制标题
DOI：
10.1021/acs.macromol.9b01676
复制
发表时间：
2019-10-08
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：
Cui, Kunpeng;Ye, Ya Nan;Gong, Jian Ping
最近的研究报告了一个多尺度结构的坚韧和自我修复的水凝胶含有物理协会。例如，来自电荷平衡的聚两性电解质（PA）的一种类型的坚韧和自修复水凝胶具有结构长度约400 nm的介观尺度双连续双网络结构。这种介观网络结构在多步破裂过程中起着至关重要的作用，这导致PA水凝胶的高韧性。本文采用渗透应力法对称地研究了软硬网络的相对强度和离子键的强度对PA凝胶性能的影响。研究发现，随着电解液渗透应力的增加，薄膜的结构由双连续双网络结构向均匀结构转变，从而导致薄膜的光学性质发生不透明-透明转变，力学性质发生粘弹性-玻璃态转变。结构转变点附近的凝胶具有高韧性（断裂能为7200 J m（-2））和高刚度（杨氏模量为12.9 MPa），这是软网络和硬网络双连续结构的协同作用。我们的工作不仅提供了一种通过调节物理缔合来调节物理水凝胶的结构和性质的方法，而且还提供了一个演示来研究它们之间的关系，但又向前迈出了一步，为围绕结构转变点设计新型坚韧和自修复材料提供了灵感。
Recent studies reported a multiscale structure in tough and self-healing hydrogels containing physical associations. For example, a type of tough and self-healing hydrogel from charge-balanced polyampholytes (PA) has a mesoscale bicontinuous double network structure with structural length around 400 nm. This mesoscale network structure plays an essential role in the multistep rupture process, which leads to the high toughness of PA hydrogels. In this work, by using an osmotic stress method, we symmetrically studied how the relative strength of soft and hard networks and the strength of ionic bonds influence the property of PA gels. We found that increasing osmotic stress of the bath solution triggers the structure transition from bicontinuous double network structure to a homogeneous structure, which drives the concurrently opaque-transparent transition in optical property and viscoelastic-glassy transition in mechanical behavior. The gels around the structural transition point were found to possess both high toughness (fracture energy of 7200 J m(-2)) and high stiffness (Young's modulus of 12.9 MPa), which is a synergy of soft network and hard network of the bicontinuous structure. Our work not only provides an approach to tune the structure and property of physical hydrogels through tuning physical association but also gives a demo to investigate their relationships, yet another step forward gives inspiration to design a new type of tough and self-healing materials around the structural transition point.