Creaming, diving and swimming microcapsules driven by chemical reactions

由化学反应驱动的乳化、潜水和游泳微胶囊

• 批准号: 254463561
• 负责人: Professor Dr. Heinz Rehage
• 金额: --
• 依托单位: Lehrstuhl für Physikalische Chemie II
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/254463561?language=en
• 关键词: Creaming; diving; swimming; microcapsules; driven

The new research project is focused on the self-propelling properties of viscoelastic microcapsules, which are used as simple model systems for biological cells. These anisometric particles are produced in a special microfluidic apparatus. Due to the onset of shear forces, which are applied during the synthesis, the capsules attain a drop-shaped geometry with a semispherical head and a small, narrow tail. The directed propulsion of these colloidal particles is stimulated by chemical reactions, which occur in the core of these capsules. A very simple driving mechanism can be realized by incorporation of potassium permanganate crystals into the hollow capsule cavities. If the outer aqueous phase contains hydrogen peroxide, these molecules diffuse through the semi-permeable membranes into the core of the capsules and react then with the solved permanganate ions. The oxygen bubbles, which are formed by this redox-reaction, induce a rapid self-propelling motion of these particles. A large number of additional organic and inorganic chemical reactions shall be used in order to activate well-defined creaming, diving or swimming motions.Oscillating chemical reactions stimulate periodic swelling and shrinking processes of the gel-like capsule membranes. On grounds of the pronounced shape asymmetry this principle might lead to new types of pulsating swimming motions. As the capsules are surrounded by thin, viscoelastic polymer membranes, they react sensitively to the onset of mechanical forces. This special feedback mechanism, which changes the size and shape of the microcapsules during flow, is of foremost interest for the understanding of basic principles of biological microswimmers. The continuous synthesis in the microfluidic apparatus allows the production of a large number of self-propelling capsules. It is, hence, possible, to investigate the swimming motion of capsule swarms. Such experiments shall be performed in the second period of the DFG-priority program. The active capsule motions involve a combination of different phenomena, such as size and shape transitions, swelling processes, osmotic pressures, diffusion of chemical compounds trough the capsule membranes, adsorption and release processes and hydrodynamic interactions. The rheological properties of the capsule membranes can be varied in order to control the swimming motions. The described soft-matter locomotion mechanisms are based on different colloidal principles and lead to the development of new types of self-propelling particles, which can be used for advanced technologies of capsule addressing and processes of controlled drug release.

新的研究项目的重点是粘弹性微胶囊的自我传播特性，这些特性被用作生物细胞的简单模型系统。这些动态颗粒是在特殊的微流体设备中产生的。由于在合成过程中施加的剪切力的发作，胶囊达到了一个滴度形的几何形状，带有半球头和小狭窄的尾巴。这些胶体颗粒的定向推进是由化学反应刺激的，化学反应发生在这些胶囊的核心中。可以通过将钾盐甘油酸钾晶体掺入空心囊腔中来实现非常简单的驾驶机制。如果外水相含有过氧化氢，则这些分子通过半渗透膜扩散到胶囊的核心中，然后与已溶液的长期内酯离子反应。由这种氧化还原反应形成的氧气气泡会引起这些颗粒的快速自传运动。为了激活定义明确的奶油，潜水或游泳运动，应使用大量其他有机和无机化学反应。振动化学反应刺激了凝胶状胶囊膜的周期性肿胀和收缩过程。在明显的形状不对称的基础上，该原理可能会导致新型的脉动游泳运动。由于胶囊被薄的粘弹性聚合物膜包围，它们对机械力的发作敏感。这种特殊的反馈机制改变了流动过程中微胶囊的大小和形状，这对于理解生物微晶状体的基本原理具有最重要的兴趣。微流体设备中的连续合成允许产生大量的自我销售胶囊。因此，有可能调查胶囊群的游泳运动。此类实验应在DFG优先计划的第二阶段进行。活动胶囊运动涉及不同现象的组合，例如大小和形状过渡，肿胀过程，渗透压，化合物的扩散槽胶囊，吸附和释放过程以及水动力相互作用。为了控制游泳运动，可以改变胶囊膜的流变特性。所描述的软性运动机制基于不同的胶体原理，并导致新型的自我销售颗粒的发展，可用于胶囊的高级技术解决和受控药物释放的过程。