Yasui Tomoki, Fujinami So, Hoshino Taiki, Kamio Eiji, Matsuyama Hideto
Research Center for Membrane and Film Technology, Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan.
RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
Soft Matter. 2020 Mar 4;16(9):2363-2370. doi: 10.1039/c9sm02174d.
Inorganic/organic double network (DN) ion gels, which are composed of an inorganic silica particle network, an organic poly(N,N-dimethylacrylamide) (PDMAAm) network, and a large amount of ionic liquid, showed excellent mechanical strength of over 25 MPa compression fracture stress at an 80 wt% ionic liquid content. The excellent mechanical strength of these inorganic/organic DN ion gels was attributed to the energy dissipation of the inorganic/organic DN structure. It has been considered that the energy dissipation in inorganic/organic DN ion gels is caused by the internal fracture of the silica particle network, which is preferentially fractured by deformation. However, no studies aiming to investigate the internal fracture of the silica particle network in inorganic/organic DN ion gels have been conducted by direct approaches. In this study, the internal fracture of the silica particle network in the inorganic/organic DN ion gel was directly evaluated by a small angle X-ray scattering (SAXS) technique. The synchrotron SAXS measurements conducted under a uniaxial loading-unloading process demonstrated that the aggregation size of the silica particle network irreversibly decreased with uniaxial stretch. Based on these results, it was clarified that the energy dissipation of the inorganic/organic DN ion gels was attributed to the internal fracture of the silica particle network.
无机/有机双网络（DN）离子凝胶由无机二氧化硅颗粒网络、有机聚（N，N-二甲基丙烯酰胺）（PDMAAm）网络和大量离子液体组成，在离子液体含量为80 wt%时表现出超过25 MPa的压缩断裂应力的优异机械强度。这些无机/有机DN离子凝胶的优异机械强度归因于无机/有机DN结构的能量耗散。人们认为无机/有机DN离子凝胶中的能量耗散是由二氧化硅颗粒网络的内部断裂引起的，二氧化硅颗粒网络在变形时优先断裂。然而，尚未有通过直接方法研究无机/有机DN离子凝胶中二氧化硅颗粒网络内部断裂的研究。在本研究中，通过小角X射线散射（SAXS）技术直接评估了无机/有机DN离子凝胶中二氧化硅颗粒网络的内部断裂。在单轴加载-卸载过程中进行的同步加速器SAXS测量表明，二氧化硅颗粒网络的聚集尺寸随着单轴拉伸而不可逆地减小。基于这些结果，明确了无机/有机DN离子凝胶的能量耗散归因于二氧化硅颗粒网络的内部断裂。
