Watanabe Takaichi, Sakai Yuko, Mori Kurumi, Ono Tsutomu
Department of Applied Chemistry, Graduate School of Environmental, Life, Natural Science and Technology, Okayama University, 3-1-1, Tsushima-naka, Kita-ku, Okayama, 700-8530, Japan.
Sci Rep. 2025 Feb 24;15(1):6666. doi: 10.1038/s41598-025-91550-7.
Multilayer microcapsules containing a small particle within a larger capsule have recently attracted considerable attention owing to their potential applications in diverse fields, including drug delivery, active ingredient storage, and chemical reactions. These complex capsules have been fabricated using interfacial polymerization or seeded emulsion polymerization. However, these methods often require complex and lengthy polymerization processes, limiting their utility, particularly in biopolymer systems. This study introduces a simple and efficient approach for preparing rattle-shaped cellulose acetate (CA) microcapsules through sequential phase separation in droplets. We systematically examine the effects of various preparation parameters, including the amount of co-solvent, initial droplet size, and flow rates, and reveal that the incorporation of a co-solvent-ethyl acetate (EA)- in the dispersed phase significantly impacts the microcapsule morphology. Our findings demonstrate a transition from a core-shell to a rattle-shaped structure as the EA concentration increases. Furthermore, the initial droplet diameter and flow rates influence microcapsule formation-larger droplets and reduced continuous-phase flow rates favor the development of multi-layered structures. These results indicate that the formation mechanism of these rattle-shaped microcapsules arises from the establishment of a radial solvent concentration gradient and subsequent phase separation within the droplets, driven by kinetic rather than thermodynamic factors.
在较大胶囊内包含小颗粒的多层微胶囊，由于其在药物递送、活性成分储存和化学反应等不同领域的潜在应用，最近引起了相当大的关注。这些复杂的胶囊已通过界面聚合或种子乳液聚合制备而成。然而，这些方法通常需要复杂且冗长的聚合过程，限制了它们的实用性，尤其是在生物聚合物体系中。本研究介绍了一种通过液滴中的顺序相分离制备拨浪鼓形醋酸纤维素（CA）微胶囊的简单有效方法。我们系统地研究了各种制备参数的影响，包括共溶剂的量、初始液滴尺寸和流速，并揭示了在分散相中加入共溶剂乙酸乙酯（EA）对微胶囊形态有显著影响。我们的研究结果表明，随着EA浓度的增加，会从核壳结构转变为拨浪鼓形结构。此外，初始液滴直径和流速会影响微胶囊的形成——较大的液滴和较低的连续相流速有利于多层结构的形成。这些结果表明，这些拨浪鼓形微胶囊的形成机制源于径向溶剂浓度梯度的建立以及随后液滴内的相分离，这是由动力学而非热力学因素驱动的。
