School of Chemical and Biological Engineering, Seoul National University , 599 Gwanak-ro, Gwanak-gu, Seoul 151-742, Korea.
ACS Nano. 2017 Oct 24;11(10):9789-9801. doi: 10.1021/acsnano.7b02894. Epub 2017 Oct 3.
Electrophotorheological (EPR) fluids, whose rheological activity is dually responsive to light and electric fields (E fields), is formulated by mixing photosensitive spiropyran-decorated silica (SP-sSiO) nanoparticles with zwitterionic lecithin and mineral oil. A reversible photorheological (PR) activity of the EPR fluid is developed via the binding and releasing mechanism of lecithin and merocyanine (MC, a photoisomerized form of SP) under ultraviolet (UV) and visible (VIS) light applications. Moreover, the EPR fluid exhibits an 8-fold higher electrorheological (ER) performance compared to the SP-sSiO nanoparticle-based ER fluid (without lecithin) under an E field, which is attributed to the enhanced dielectric properties facilitated by the binding of the lecithin and SP molecules. Upon dual application of UV light and an E field, the EPR fluid exhibits high EPR performance (ca. 115.3 Pa) that far exceeds its separate PR (ca. 0.8 Pa) and ER (ca. 57.5 Pa) activities, because of the synergistic contributions of the PR and ER effects through rigid and fully connected fibril-like structures. Consequently, this study offers a strategy on formulation of dual-stimuli responsive smart fluid systems.
电流变（ER）液是一种混合了光敏螺吡喃修饰的二氧化硅（SP-sSiO）纳米颗粒、离子型卵磷脂和矿物油的双响应流变活性材料，其流变活性对光和电场（E 场）都有响应。通过卵磷脂和硫代靛蓝（MC，SP 的光致异构形式）在紫外（UV）和可见光（VIS）光照射下的结合和释放机制，开发出了可逆光流变（PR）活性的 EPR 流体。此外，与不含卵磷脂的基于 SP-sSiO 纳米颗粒的 ER 流体相比，E 场下 EPR 流体的 ER 性能提高了 8 倍，这归因于卵磷脂和 SP 分子结合所带来的介电性能的增强。在 UV 光和 E 场的双重作用下，EPR 流体表现出高的 EPR 性能（约 115.3 Pa），远远超过其单独的 PR（约 0.8 Pa）和 ER（约 57.5 Pa）活性，这是由于 PR 和 ER 效应通过刚性和完全连接的纤维状结构的协同贡献。因此，本研究提供了一种双刺激响应智能流体系统的配方策略。
