Abstract:

The nano-dispersion formed by the hydrophobic nanoparticles dispersed in the organic system has unique physical and chemical properties and important application value. Currently, there is limited controllability in particle dispersion into organic phase during preparation. The agglomeration of nanoparticles, which results in not only particle sedimentation and loss but also decrease in the performance of nanodispersions, often occurs in their preparation, surface modification, and final application processes. In this study, two types of CuO nanodispersions, CuO-base oil nanofluids and CuO-based precursors for composite films, are adopted as the typical systems. A method for the preparation of high-concentration CuO-based nanodispersions by in situ dispersion of surface-modified CuO nanoparticles into the oil phase has been developed, while a plate-type microchannel was constructed to initiate microdroplet coalescence for the enhancement of particle dispersion. For the case of CuO-base oil nanofluids, the nanofluids with a high particle concentration of 2% (vol) and an average CuO particle size of approximately 30 nm could be controllably prepared. The viscosity, thermal conductivity, and stability of the nanofluids have been measured. A thermal conductivity of 0.184 W·m^-1·K^-1 was obtained for the 2% (vol) nanofluid along with an excellent stability. For the case of CuO-based precursors, the CuO-polydimethylsiloxane (PDMS) composite films prepared have exhibited remarkable antibacterial properties with a highly stable composite layer of CuO nanoparticles. On the basis of the systematic experimental study, the important role of in situ dispersion method in enhancing the efficient dispersion of surface-modified particles was proved. The effect of nanoparticle properties and dispersion behaviors on the performance of the dispersed particles have also been experimentally determined.

Key words: microchannels, composites, in situ dispersion, copper oxide, nanofluids, films, droplet coalescence

摘要：

疏水纳米颗粒分散于有机体系中形成的纳米分散体，具有独特的理化性质和重要的应用价值。其中，纳米颗粒的单分散性、均匀性和稳定性是决定纳米分散体性能的关键。以CuO纳米分散体作为纳米流体和复合薄膜前体这一典型体系为研究对象，通过设计平板型微通道实现了CuO纳米分散体制备过程中的液滴聚并和改性CuO纳米颗粒的原位分散。制备了颗粒体积分数达2%、平均粒径约30 nm的CuO-基础油纳米流体，该纳米流体具有良好的稳定性和达到0.184 W·m^-1·K^-1的较高热导率；制备的CuO-PDMS（聚二甲基硅氧烷）复合薄膜具有较强的抗菌性能和颗粒复合层稳定性。通过系统性实验研究，证明了原位分散方法在强化改性颗粒高效分散中的重要作用，确定了颗粒性能及分散行为对分散体性能的影响规律。

关键词: 微通道, 复合材料, 原位分散, 氧化铜, 纳米流体, 膜, 液滴聚并