Road Engineering/Sealing Components, Empa Dübendorf , CH 8600 Dübendorf, Switzerland.
ACS Appl Mater Interfaces. 2017 Oct 25;9(42):37364-37373. doi: 10.1021/acsami.7b09371. Epub 2017 Oct 11.
Microcapsules are important for the protection, transport, and delivery of cargo in a variety of fields but are often too weak to withstand the high mechanical stresses that arise during the preparation and formulation of products. Although thick-shell strong capsules have been developed to circumvent this issue, the microfluidic or multistep methods utilized thus far limit the ease of fabrication and encapsulation throughput. Here, we exploit the phase separation of ternary liquid mixtures to achieve a high-throughput fabrication of strong bilayer microcapsules using a one-step bulk emulsification process. Phase separation is induced by the diffusion of water from the continuous phase into droplets that initially contain a mixture of monomers, cross-linkers, an initiator, and cosolvent γ-butyrolactone. The double emulsions generated via such a phase separation are converted into microcapsules through a polymerization reaction triggered by UV illumination. Surprisingly, the shells of the consolidated capsules exhibit a hard-soft bilayer structure that can be designed to show a resilient eggshell-like fracture behavior. Our method allows for the production of large volumes of microcapsules with such a strong bilayer shell within a time scale of only a few minutes, thus offering an enticing pathway toward the high-throughput fabrication of mechanically robust encapsulation systems.
微胶囊在许多领域对于货物的保护、运输和输送都很重要，但它们往往太脆弱，无法承受产品制备和配方过程中产生的高机械应力。尽管已经开发出厚壳强胶囊来解决这个问题，但迄今为止所采用的微流控或多步方法限制了制造和封装的容易程度和通量。在这里，我们利用三元液体混合物的相分离，通过一步 bulk 乳化过程实现了高通量制造强双层微胶囊。通过水从连续相扩散到最初含有单体、交联剂、引发剂和助溶剂 γ-丁内酯混合物的液滴来引发相分离。通过这种相分离产生的双乳液通过 UV 照射引发的聚合反应转化为微胶囊。令人惊讶的是，固结胶囊的壳表现出硬-软双层结构，可以设计为具有弹性蛋壳状断裂行为。我们的方法允许在仅几分钟的时间尺度内生产具有这种强双层壳的大量微胶囊，从而为机械坚固的封装系统的高通量制造提供了诱人的途径。
