Experimental investigation of the effects of copolymer surfactants on flow-induced coalescence of drops
Experimental investigation of the effects of copolymer surfactants on flow-induced coalescence of drops
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DOI：
10.1063/1.2409735
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发表时间：
2007-02
影响因子：
4.6
通讯作者：
Yosang Yoon;Adam S. Hsu;L. Leal
中科院分区：
文献类型：
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作者：
Yosang Yoon;Adam S. Hsu;L. Leal
流动诱导聚结的一对聚合物液滴进行了研究，在单独的液滴的水平，使用四辊磨机，以了解该过程是如何影响的存在下的共聚物在滴界面。实验系统由悬浮在聚二甲基硅氧烷（PDMS）中的聚丁二烯（PBd）液滴组成。通过官能化均聚物（PBd-COOH和PDMS-NH 2）之间的反应在液滴界面处产生共聚物。这些实验的参数范围比我们早期的Hu等人[Phys. Fluids 12，484（2000）]和Ha等人[Phys. Fluids 15，849（2003）]的研究更广，试图理解我们早期研究中发现的令人困惑的结果。实验结果是一致的定性机制的固定化的薄膜之间的滴由于流动引起的Marangoni效应的边界。存在一个临界或最小共聚物界面覆盖率（Γmin），高于该值时，共聚物效应变得与覆盖率或界面张力无关。
Flow-induced coalescence of a pair of polymeric drops was studied at the level of individual drops, using a four-roll mill, to understand how the process is affected by the presence of a copolymer at the drop interface. The experimental system consisted of polybutadiene (PBd) drops suspended in polydimethylsiloxane (PDMS). Copolymers were produced at the drop interface by a reaction between functionalized homopolymers (PBd-COOH and PDMS-NH2). The experiments were carried out over wider ranges of parameters than our earlier studies of Hu et al. [Phys. Fluids 12, 484 (2000)] and Ha et al. [Phys. Fluids 15, 849 (2003)], in an attempt to understand the puzzling results found in our earlier studies. The experimental results were consistent with a qualitative mechanism of immobilization of the boundaries of the thin film between drops due to a flow-induced Marangoni effect. A critical or minimum copolymer interfacial coverage (Γmin) exists, above which the copolymer effect becomes independent of the coverage or...