新型Janus乳液的形成机理研究及可控微/纳双面结构的构筑

Janus Particles (JPs), with different composition or morphology as its hemispheres, have special properties of isotropic and asymmetry. They have been used as colloidal surfactants, chemical and biological sensors, display materials of the electronic paper, and self-motile colloidal particles. The discovery of Janus emulsion, with two immiscrible oils composing the inner droplets, is a breakthrough in the field of emulsion science. What is more, it provides a novel way to construct the Janus structure. Hence, it is essential to study the fundamental properties of the novel Janus emulsion from the view of industrial applications as well as of academic curiosities. The present proposal will focus on how to prepare Janus emulsion, and how to construct the controllable macro-nano Janus structure with Janus emulsion as template. Systematical investigations will start with the formation mechanism, stability, and the phase inversion. Subsequently, the destabilize processes of creaming, sedimentation, flocculation, coalescence, and the Ostwald ripening will be studied in terms of surfactant films, interaction force between the droplets, and the viscosity of the system. What is more important, the structure of the emulsion droplets including the size distribution and the ratio of the two hemispheres will be controlled by the composition of emulsion, the energy of emulsification, and the methods of phase inversion temperature (PIT) and phase inversion concentration (PIC). Based on the fundamental investigations on the novel Janus emulsion, the Janus materials will be synthesized by replacing the oil phases with polymerizable monomers. And the magnetic nanoparticles and pharmaceutical molecules will be adulterated into the emulsion to realize the functionalization of Janus particles.

双面粒子的两个半球具有不同的化学组成或形貌，独特的各向异性使其在分子识别和自组装、生物传感器、界面修饰等领域有广泛的应用。新型Janus乳液于2011年被研究发现，其内相液滴为双面结构，由互不相溶的两种油组成。Janus乳液的发现不仅是人类对传统乳液认识的全新突破，而且为双面结构的构筑开辟了新的发展方向。本项目拟从界面膜的分子组成及性质、内外相的物理化学特性阐明Janus乳液的形成机理；基于三组份相图考察体系的组成及比例对Janus乳液相区的影响，研究双面结构的构筑规律，从而构建Janus乳液双面结构的理论模型；通过内外相物理化学特性的改变，系统研究絮凝、凝聚、沉降、乳析、奥氏熟化等相转变特性；通过体系组成和比例的调节、乳化工艺的优化，实现微/纳双面结构的调控。此外，基于Janus乳液独特的结构，以其为模板合成新型双面高分子微/纳材料，并掺杂磁性分子、药物分子，实现双面材料的功能化。

Janus乳液是由一步涡旋混合法制备的新型乳液，其内相液滴由两种互不相溶的油构成两个相对独立的“两室”，内相液滴中两室结构丰富了乳液的形式；液滴内部具备两个组成各异的微相区，可以选择性增溶不同的功能性分子；同时，各室的形状不对称、体积互不相同使得液滴的拓扑结构具有各向异性，在材料合成、生物医药等领域有潜在的应用前景。本项目紧密围绕项目目标，考察了该新型Janus乳液的形成机理，揭示了三相界面张力是Janus液滴形成的关键因素。同时实现了Janus液滴的双面比例、油/油界面的曲率、三相接触圆的位置等拓扑结构参数的可控调节。此外，在保持Janus液滴拓扑结构不变的情况下，实现了液滴大小由微米尺度到纳米尺度的连续可控转变。另一方面，制备了以可聚合单体为油相的Janus乳液，并以此乳液液滴为模板，批量制备结构不对称粒子。所制备的不对称粒子的形貌可由“新月形”转变为“满月形”，并且粒子的尺度调节在微米到纳米范围连续可控。本项目提出的制备方法兼具低成本，高产量，宽尺寸的特点，开创了不对称粒子合成的新方法。在本基金的支持下，已发表SCI论文11篇，申请专利2项，已获授权1项。