改性纤维素微球包裹液体制备液体弹珠及其结构特性研究

Liquid marbles are liquid droplets that are encapsulated by micro- or nano-scaled solid particles with low surface energy. Since the apparent surface energy of liquid is decreased by the coverage of hydrophobic materials, the liquid marbles are non-wetting to the solid surfaces and maintain the spherical shape on a substrate without liquid leakage. Depending on the components of the surrounding particles, liquid marbles can be manipulated by external forces, such as gravity, electric field, and magnetic field. The unique morphologies and properties are providing liquid marbles increasing research interest for various potential applications in sensors, transport of microfluids, cosmetics, microreactors, and controlled drug delivery. In this proposal, bioinspired by the plant gall surface created by aphids, we aim to explore the liquid marbles prepared using cellulose, which is the most abundant natural polymer on Earth. The cellulose microspheres with various diameter and polydispersity will be prepared using an inverse suspension strategy. According to the surface properties of cellulose microspheres incorporated with Fe3O4, novel poly(DOPAm-co-PFHEA) and poly(DOPAm-co-OA) will be synthesized. After surface modification and functionalization with different chemicals, such as acetic anhydride, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, n-octadecyltrimethoxysilane, Fe3O4/poly(DOPAm-co-PFHEA) and Fe3O4/poly(DOPAm-co-OA), the cellulose microspheres with different surface energy and functionality will be obtained. The liquid marble will be fabricated by dropping liquid to the hydrophobic powder and followed by gentle shaking. A wide range of liquids, such as water, glycerol and some ionic liquids, will be used to fabricate liquid marbles with different morphology and properties. The static and dynamic (manipulation by magnetic field, floating on water, bounce, and compress) behavior of liquid marbles will be performed systematically. The interaction between the microparticles and liquids at air-liquid interface, and the interaction between the microparticles in the shell will be studied in details. The effect of microstructures, size, polydispersity, and hydrophobicity of modified cellulose microspheres on the stability of liquid marbles will be demonstrated. The unique advantage of cellulose as the stating material to fabricate liquid marbles will be clarified. Our proposal for liquid marbles inspired by nature will provide a fundamental and theory insight into the preparation and application of controllable liquid marbles with high stability and biocompatible interface materials with ideal properties.

液体弹珠是利用具有低表面能的微/纳米颗粒包裹液体而制成的不粘湿液滴，在传感器、微流体转移、化妆品、微反应器、可控药物传送系统等领域有广泛的应用前景。本项目拟利用自然界丰富的可再生资源──纤维素为基本原料，对自然界中蚜虫等生物所制备的液体弹珠的结构特性进行仿生研究。采用反相悬浮法制备不同粒径大小和粒径分布的纤维素微球。合成特定功能的共聚物，对纤维素微球进行各种改性来构建理想疏水性的功能微球。用各种改性纤维素微球包裹不同表面张力的液体制取不同结构特性的液体弹珠，研究在静态和磁力驱动、水面漂浮、弹跳、压缩等动态条件下，改性微球在球形气──液界面上与液体的相互作用，阐明微球的微观结构、粒径大小、粒径分布及疏水性对液体弹珠稳定性的影响机制，探明纤维素作为基底材料制备液体弹珠的独特优势，为高稳定性和可操控性的液体弹珠和生物相容性超疏水界面材料的构建和应用提供现实依据和理论基础。

液体弹珠是利用具有低表面能的微/纳米颗粒包裹液体而制成的不粘湿液滴，在传感器、微流体转移、化妆品、微反应器、可控药物传送系统等领域有广泛的应用前景。本项目利用自然界丰富的可再生资源──纤维素为基本原料，对液体弹珠的结构特性进行了研究。制备了500μm～24nm粒径大小的纤维素微粒。合成了具有超疏水的多巴共聚物Poly(DOPAm-co-PFOEA)，对纤维素微粒进行各种改性构建了超疏水磁性微粒。纤维素微球的表面被Fe3O4纳米粒子修饰，在粒子的最外层为多巴含氟共聚物高分子。共聚物上的儿茶酚基团使共聚物与Fe3O4纳米粒子紧密结合，而含氟基团露在最外层，赋予纤维素微球具有极低的表面能，使纤维素微球表现出超疏水性。超疏水磁性纤维素微粒可包裹水、N,N-二甲基甲酰胺、甲苯和乙醇等不同的液体形成稳定的液体弹珠，而传统的疏水材料聚四氟乙烯却无法包裹甲苯和乙醇等低表面能物质形成稳定液体弹珠。形成的液体弹珠具有磁响应性，在磁场作用下可对其操控，能够垂直或者水平移动，在微流体和液滴转移等领域具有潜在的应用价值。研究了在磁力驱动、油中除水、水面漂浮等条件下，改性微粒在球形气──液界面上与液体的相互作用，阐明了纤维素微粒的微观结构和疏水性对液体弹珠稳定性的影响机制。超疏水磁性纳米纤维素粒子可用来除去油中的微小水滴，在油中的液体弹珠被切割后，能生成两个液体弹珠，具有显著的自愈合性能，在油水分离领域具有潜在的应用。本项目的研究为高稳定性和可操控性的纤维素基液体弹珠和生物相容性超疏水界面材料的构建和应用提供现实依据和理论基础。