基于液-液相分离的微流控Janus液滴制备方法研究

发布时间：2018-11-04 09:12

【摘要】：Janus粒子是由化学组成不同、极性不同的两个球面构成的微米或纳米粒子,具有两亲性和不对称性,在自组装、催化剂、生物传感等领域具有广阔的应用前景。传统Janus粒子的制备方法存在单分散性差、批次间差异大等问题。经典微流控液滴技术可形成尺寸均一的Janus粒子,但产量很低,无法规模制备。本文将液-液相分离与微流控乳化技术相结合,以单相液滴形成技术制备多元混合物液滴,分别在助溶剂挥发和温度的作用下,多元混合物液滴发生相分离,形成Janus液滴,为进一步规模化制备Janus粒子打下基础。1.助溶剂挥发诱导形成Janus液滴。首先以微流控单相液滴形成单分散三元混合物液滴,三元混合液滴内的助溶剂快速挥发,导致液滴液-液相分离,由均相变化成Janus形态。通过调节三元混合物的组成和体积比,Janus液滴各部分的化学性质和形貌均可灵活调节和精确控制。当三元混合物推广到四元混合物时,可制备构型更复杂的Janus液滴,比如核-壳式Janus液滴、三元Janus液滴、多核Janus液滴等。以上述Janus液滴为模板,通过紫外光引发聚合,合成了半球形、多孔半球形等具有不对称结构的微米颗粒,且颗粒形貌可经溶液组成和体积比灵活调节。2.温度诱导相分离形成Janus液滴。以温敏性离子液体与水形成的均相二元混合物为分散相,矿物油(2%wt表面活性剂)为连续相,在微流控芯片平台形成了单分散的二元均相液滴。在氧化铟锡(ITO)电极加热下,该二元均相液滴的温度升高,超过离子液体的临界相变温度时,液滴中的离子液体与水相分离,形成Janus液滴。当停止加热,温度降至离子液体临界相变温度以下,Janus液滴逐渐恢复成均相二元液滴。通过调节离子液体和水的体积比,Janus液滴的形貌可以灵活调节和精确控制。液滴构型能在单相球形和Janus构型间可逆切换,在智能材料制备方面具有潜在的应用价值。
[Abstract]:Janus particles are micron-or nano-particles composed of two spherical spheres with different chemical composition and different polarity. They are amphiphilic and asymmetric, and have a broad application prospect in self-assembly, catalyst, biosensor and other fields. The traditional preparation method of Janus particles has some problems, such as poor monodispersity and large difference among batches. The classical microfluidic droplet technique can form Janus particles of uniform size, but the yield is very low and can not be prepared on a large scale. In this paper, the liquid-liquid phase separation and microfluidic emulsification technology are combined to prepare the multi-component mixture droplets by single-phase droplet formation technology. Under the action of the co-solvent volatilization and temperature, the multi-component mixture droplets are separated to form Janus droplets, respectively. For further large-scale preparation of Janus particles lay the foundation. 1. The co-solvent volatilization induces the formation of Janus droplets. Firstly, the single dispersed ternary mixture droplets were formed by microfluidic single phase droplets, and the cosolvent in the ternary mixture droplets rapidly volatilized, resulting in the separation of droplets from liquid to liquid, which changed from homogeneous to Janus morphology. By adjusting the composition and volume ratio of ternary mixtures, the chemical properties and morphology of various parts of Janus droplets can be adjusted flexibly and precisely controlled. When ternary mixtures are extended to quaternary mixtures, more complex Janus droplets can be prepared, such as core-shell Janus droplets, ternary Janus droplets, polynuclear Janus droplets and so on. Using the above Janus droplets as templates, microparticles with asymmetric structure, such as hemispherical and porous hemispherical particles, were synthesized by ultraviolet photoinitiation polymerization. The morphology of the microparticles can be adjusted flexibly by solution composition and volume ratio. 2. The temperature induced phase was separated to form Janus droplets. Using homogeneous binary mixture of temperature sensitive ionic liquid and water as dispersed phase and mineral oil (2%wt surfactant) as continuous phase, monodisperse binary homogeneous droplets were formed on microfluidic chip platform. When the indium tin oxide (ITO) electrode is heated, the temperature of the binary homogeneous droplet increases. When the temperature exceeds the critical phase transition temperature of the ionic liquid, the ionic liquid in the droplet is separated from the water phase to form the Janus droplet. When the heating stops and the temperature drops below the critical phase transition temperature of ionic liquids, the Janus droplets gradually recover into homogeneous binary droplets. By adjusting the volume ratio of ionic liquids to water, the morphology of Janus droplets can be adjusted flexibly and accurately. Droplet configurations can be switched between single-phase spherical and Janus configurations and have potential applications in the preparation of smart materials.
【学位授予单位】：江苏师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB30

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