Polymer Science and Engineering Department, University of Massachusetts Amherst , Amherst, Massachusetts 01003, United States.
Beijing Advanced Innovation Center for Soft Matter, Science and Engineering, Beijing University of Chemical Technology , Beijing 100029, China.
Nano Lett. 2017 Oct 11;17(10):6453-6457. doi: 10.1021/acs.nanolett.7b03462. Epub 2017 Sep 15.
Nanoparticle-surfactants (NPSs) assembled at water-oil interfaces can significantly lower the interfacial tension and can be used to stabilize liquids. Knowing the formation and assembly and actively tuning the packing of these NPSs is of significant fundamental interest for the interfacial behavior of nanoparticles and of interest for water purification, drug encapsulation, enhanced oil recovery, and innovative energy transduction applications. Here, we demonstrate by means of interfacial tension measurements the high ionic strength helps the adsorption of NPSs to the water-oil interface leading to a denser packing of NPSs at the interface. With the reduction of interfacial area, the phase transitions from a "gas"-like to "liquid" to "solid" states of NPSs in two dimensions are observed. Finally, we provide the first in situ real-space imaging of NPSs at the water-oil interface by atomic force microcopy.
纳米粒子-表面活性剂（NPSs）在油水界面组装可以显著降低界面张力，并可用于稳定液体。了解这些 NPSs 的形成和组装，并主动调整它们的组装方式，对于纳米粒子的界面行为具有重要的基础意义，对于水净化、药物封装、提高石油采收率以及创新的能量转换应用也具有重要意义。在这里，我们通过界面张力测量证明，高离子强度有助于 NPSs 吸附到油水界面上，从而导致 NPSs 在界面上更紧密地组装。随着界面面积的减少，在二维空间中观察到 NPSs 从“气体”相到“液体”相再到“固体”相的相变。最后，我们通过原子力显微镜首次提供了在油水界面处 NPSs 的原位实空间成像。
