Natural polyphenols such as tannins, procyanidins, and cardanol are widely used in the field of surface chemistry. To further explore the application of the other natural polyphenols, epigallocatechin gallate (EGCG) derived from green tea was employed. EGCG is an ideal choice to achieve a hyperbranched surfactant. A precursor (EGA) was first obtained by the reaction among the EGCG, formaldehyde, and tetraethylenepentamine (TEPA). EGA surfactants were synthesized in the high-pressure kettle by anionic polymerization with EGA, propylene oxide (PO) and ethylene oxide (EO). The good consistency between the designed PO/EO ratios of EGA surfactants and the theoretical values were proved by ¹H NMR spectra. The increase of micelle size with the increase of surfactant concentration and NaCl concentration was observed both by dynamic light scattering and TEM. Result shows EGA surfactants with higher absolute value of ${∆G°}_{\mathit{ads}}$ and high interfacial activity have potential demulsification applications. As a result, toward aging oil emulsions of the South China Sea Oilfield, the surfactants exhibited excellent demulsification performance. The dehydration ratio reached 94.3% at a low concentration of 100 mg L⁻¹ for 100 min at 70 °C, while the commercial demulsifier SP169 only reached 86.9%. This emulsion could be dehydrated completely at even higher temperature at 80 °C as well as higher dosage in 150 mg L⁻¹. Meanwhile, the demulsification ratios of crude oil emulsions and aging oil emulsions produced from Bohai Oilfield reached 94.0% and 95.0%, respectively. Coming from the waste oil after demulsification, aging oil emulsions have more additives than crude oil emulsions, therefore the former is more stable. In addition to the above high interfacial activity, this excellent demulsification performance may result from the assistance of polyphenol structure and multiple branches of EGA surfactants. The demulsification of three above emulsions demonstrated that although there exist great differences in properties of emulsions, EGA surfactants exhibit the universality of efficient demulsification.

天然多酚，如单宁，原花青素和腰果酚，广泛用于表面化学领域。为了进一步探索其他天然多酚的应用，采用了衍生自绿茶的表没食子儿茶素没食子酸酯（EGCG）。EGCG是获得超支化表面活性剂的理想选择。首先通过EGCG，甲醛和四亚乙基五胺（TEPA）之间的反应获得前体（EGA）。EGA表面活性剂是在高压釜中通过与EGA，环氧丙烷（PO）和环氧乙烷（EO）进行阴离子聚合而合成的。EGA表面活性剂的设计PO / EO比和理论值之间的良好的一致性被证明¹1 H NMR谱。通过动态光散射和TEM观察到胶束尺寸随表面活性剂浓度和NaCl浓度的增加而增加。结果表明，EGA表面活性剂的绝对值较高${\Delta G°}_{\mathit{广告}}$和高界面活性具有潜在的破乳应用。结果，对于南海油田的老化的油乳液，表面活性剂表现出优异的破乳性能。在70 °C下，在100 mg  L ^-1的低浓度下100分钟，脱水率达到94.3％ ，而商用破乳剂SP169仅达到86.9％。该乳液甚至可以在更高的温度（80  °C）和更高的150 mg  L ^-1剂量下完全脱水。。同时，渤海油田生产的原油乳液和陈化油乳液的破乳率分别达到94.0％和95.0％。破乳后来自废油的老化油乳液比原油乳液具有更多的添加剂，因此前者更稳定。除了上述高界面活性外，这种优异的破乳性能还可以归因于多酚结构和EGA表面活性剂的多个分支的辅助。上述三种乳液的反乳化作用表明，尽管乳液的性能存在很大差异，但EGA表面活性剂表现出高效反乳化的普遍性。