College of Materials Science and Engineering, Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, Nanshan District Key Laboratory for Biopolymers and Safety Evaluation, Shenzhen University, Shenzhen 518055, P. R. China.
South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology, Guangzhou 510640, China.
Soft Matter. 2023 Jun 21;19(24):4536-4548. doi: 10.1039/d3sm00314k.
Pickering emulgels stabilized by graphene oxide (GO) with didodecyldimethylammonium bromide (DDAB) as an auxiliary surfactant and liquid paraffin as the oil phase have proved to be an excellent 3D printable ink. This paper elucidates the structure of such emulgels by a combination of microscopy before and after intensive shear as well as broadband dielectric spectroscopy and rheology in the linear and nonlinear regime. An increase of the DDAB surfactant and GO-contents leads to a systematic increase of modulus and viscosity, a reduction of the limits of the nonlinear regime and a more complicated variation of the normal forces, with negative normal forces at high shear rate for low GO-contents and positive normal forces at high GO-contents. The interfacial jamming behavior studied by morphology, rheology and dielectric spectroscopy is explained based on droplet deformation, jamming and recovery phenomena.
由氧化石墨烯 (GO) 稳定的 Pickering 乳剂，与双十二烷基二甲基溴化铵 (DDAB) 作为辅助表面活性剂和液体石蜡作为油相，已被证明是一种出色的 3D 可打印墨水。本文通过在强剪切前后的显微镜以及在线性和非线性区域的宽频介电光谱和流变学的组合，阐明了这种乳剂的结构。DDAB 表面活性剂和 GO 含量的增加会导致模量和粘度的系统增加，非线性区域的限制降低，以及正常力的更复杂变化，在低 GO 含量时在高剪切速率下会出现负正常力，而在高 GO 含量时会出现正正常力。通过形态学、流变学和介电光谱研究的界面阻塞行为，基于液滴变形、阻塞和恢复现象进行了解释。
