Alting Meyer T, Haase Martin F
Van 't Hoff Laboratory of Physical and Colloid Chemistry, Department of Chemistry, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands.
Soft Matter. 2025 Jan 22;21(4):760-769. doi: 10.1039/d4sm01213e.
Bicontinuous particle-stabilized emulsions (bijels) are unique soft materials that combine the bulk properties of two immiscible fluids into a single interconnected structure. This structure is achieved through the formation of two interwoven fluid networks, stabilized by an interfacial layer of colloidal particles. Bijels with submicron-scale domain networks can be synthesized solvent transfer-induced phase separation (STrIPS). However, the fluid network structure in STrIPS-bijels tends to degrade over time, limiting their practical applications. In this study, we identify that the destabilization of STrIPS-bijels is driven by the exchange of matter between the bijel and the surrounding oil phase. Confocal laser scanning microscopy reveals that over time, aqueous components from the bijel dissolve into the surrounding oil, leading to an inward flow of oil into the bijel. This process disrupts the fluid bicontinuous structure within hours. To extend the stability of the bijel to several weeks, we explore strategies to reduce the dissolution of the aqueous phase and the inflow of oil. Specifically, we investigate the effects of the oil's chemical composition and properties, as well as modifications to the surface chemistry of the supporting glass substrates. Our results show that while the particle scaffold of STrIPS-bijels exhibits long-term stability, the maintenance of the fluid bicontinuous network depends on minimizing the loss of aqueous components. The enhanced control over the stability of the fluid bicontinuous structure developed in this work is critical for advancing STrIPS-bijels as functional materials for applications in catalysis, separations, and energy storage.
双连续颗粒稳定乳液（bijels）是一种独特的软材料，它将两种互不相溶流体的整体性质结合在一个单一的相互连接结构中。这种结构是通过形成两个相互交织的流体网络实现的，该网络由一层胶体颗粒界面层稳定。具有亚微米级畴网络的bijels可以通过溶剂转移诱导相分离（STrIPS）合成。然而，STrIPS-bijels中的流体网络结构往往会随着时间而降解，限制了它们的实际应用。在本研究中，我们确定STrIPS-bijels的失稳是由bijel与周围油相之间的物质交换驱动的。共聚焦激光扫描显微镜显示，随着时间的推移，bijel中的水性成分溶解到周围的油中，导致油向bijel内部流动。这个过程在数小时内就会破坏流体双连续结构。为了将bijel的稳定性延长至数周，我们探索了减少水相溶解和油流入的策略。具体来说，我们研究了油的化学成分和性质的影响，以及对支撑玻璃基板表面化学的改性。我们的结果表明，虽然STrIPS-bijels的颗粒支架具有长期稳定性，但流体双连续网络的维持取决于将水性成分的损失降至最低。本工作中对流体双连续结构稳定性的增强控制对于推动STrIPS-bijels作为催化、分离和能量存储应用的功能材料至关重要。
