物理化学学报 >> 2020, Vol. 36 >> Issue (10): 1910007.doi: 10.3866/PKU.WHXB201910007

所属专题: 胶体与界面化学前沿

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液体弹珠:制备策略、物理性质及应用探索

罗新杰, 张熙, 冯玉军()   

  • 收稿日期:2019-10-07 录用日期:2019-12-03 发布日期:2020-06-11
  • 通讯作者: 冯玉军 E-mail:yjfeng@scu.edu.cn
  • 作者简介:冯玉军,1999年获西南石油大学应用化学工学博士学位,2000–2004年先后在法国科研中心和法国石油研究院从事博士后研究以及在法国波城大学担任助理研究员。2004年加入中国科学院成都有机化学研究所,2012年转入四川大学工作。现为四川大学高分子研究所研究员、博士生导师。主要从事智能软物质材料的研究
  • 基金资助:
    国家自然科学基金(21773161);国家自然科学基金(U1762218)

Liquid Marbles: Fabrication, Physical Properties, and Applications

Xinjie Luo, Xi Zhang, Yujun Feng()   

  • Received:2019-10-07 Accepted:2019-12-03 Published:2020-06-11
  • Contact: Yujun Feng E-mail:yjfeng@scu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21773161);the National Natural Science Foundation of China(U1762218)

摘要:

液体弹珠是被粉末颗粒包裹形成的不润湿的液滴。由于其简便的制备过程,丰富的原料来源,不润湿/不黏附、良好的弹性和稳定性等性质,以及在液滴微流控、传感器、控制释放和微反应器等领域的良好应用前景,液体弹珠近年来受到广泛关注。针对近十几年来液体弹珠领域的研究进展,本文对液体弹珠的制备策略、形成机理、物理性质以及相关应用,尤其是在微反应器领域的应用,进行了详细地归纳与分析,探讨了影响液体弹珠稳定性的因素以及提升其稳定性的策略,并指明了当前所面临的挑战,展望了未来的发展方向和应用前景。

关键词: 液体弹珠, 粒子, 液滴, 润湿, 疏水性, 微反应器

Abstract:

Liquid marbles (LMs) are liquid droplets coated with a layer of lyophobic particles at the air-liquid interface. Since the pioneering work by Aussillous et al. in 2001, LMs have attracted significant attention owing to their facile fabrication, flexibility in the choice of the constituent particles and liquids, intriguing properties such as non-wetting and non-adhesive nature, satisfactory elasticity and stability, as well as promising applications in microfluidics, sensors, controlled release, and microreactors. The classical strategy for the preparation of LMs involves rolling a small volume of a droplet on a lyophobic powder bed for complete encapsulation of the liquid by the particles. In addition, various innovative methods, including electrostatic and coalescent approaches, have been developed for preparing special LMs with a complicated structure or morphology. Diverse materials such as water, surfactant solutions, liquid metals, reagents, blood, and even viscous adhesives have been employed as the internal liquid for the fabrication of LMs. Theoretically, any particulates such as lycopodium, polytetrafluoroethylene, Fe3O4, SiO2, and graphite grains can be employed as the outer coating, but they are usually required to be lyophobic with sizes of less than hundreds of microns. The unique structure of the particle-covered droplet and the dual solid-liquid characteristics endow LMs with some unique and interesting properties, especially the non-wetting and non-adhesive nature. As the lyophobic coating particles restrain the internal liquid from contacting the substrate, LMs can move easily across either solid or liquid surfaces, neither wetting the substrate nor contaminating the internal liquid. An equally fascinating property of LMs is their satisfactory stability, which is necessary for most of their applications. The high stability of LMs stems from the protection of the coating powders and is embodied in both good mechanical stability (remaining intact after being released from a certain height or under a certain compression) and long lifetime (greatly suppressing the evaporation of the internal liquid). These extraordinary properties make LMs promising candidates for use in multitudinous fields, especially droplet microfluidics and microreactors. The potential application of LMs in microfluidics is ascribed to their non-wetting, non-adhesive nature and other features such as an ability to float on a liquid surface, coalescence, split, a small force of rolling friction, and response to external forces. Notably, LMs hold great promise for applications in microreactions, because they can create a confined reaction microenvironment, minimize reagent usage, facilitate unhindered gas exchange between the internal liquid medium and the surrounding environment, and allow the entry/exit of the reactants/products. We herein review the recent advances in LMs, such as manufacturing techniques, formation mechanisms, physical properties, and emerging applications. In particular, much attention is paid to the factors affecting the stability of LMs and the potential strategies to increase their stability. Moreover, this review discusses the challenges in the future development of LMs, suggests several possible ways of addressing these challenges, and forecasts the future development directions. We believe that this review can help researchers gain a better understanding of LMs and promote their further advances.

Key words: Liquid marble, Particle, Droplet, Wettability, Hydrophobicity, Microreactor

MSC2000: 

  • O647