Abstract Tannic acid (TA)-aminopropyltriethoxysilane (APTES) coating has excellent hydrophilicity, and can be applied to a variety of materials. But it has poor stability in the air. To improve its stability, we have developed TA-APTES-Fe(III) coating in our previous work, but there are still some problems remained such as tedious steps, and undesirable anti-crude oil-adhesion performance, etc. Besides, both TA-APTES and TA-APTES-Fe(III) coating cannot realize the hydrophilic modification of the inner surfaces of porous polypropylene (PP) membrane. To solve the above mentioned problems, we developed superhydrophilic and stable TA-APTES- tetraethylorthosilicate (TEOS) coating via one-step process in this study. The new coating can realize the superhydrophilic modification of the inner surfaces of porous PP membrane, and endows the PP membrane with good water permeability, which cannot be realized by our previously reported TA-APTES and TA-APTES-Fe(III) coating. Besides, the stability of the coating is greatly improved by introducing stable alcoholic hydroxyl groups derived from TEOS, and the resultant modified membrane can keep superhydrophilic (CA about 0°) and underwater superhydrophobic (underwater oil CA above 150°) even after being stored in air for more than 6 months, ultrasonic treatment for 10 min, or being rinsed by water for 24 h (3000r/min), exhibiting outstanding stability. More importantly, the crude oil adhesion force of the new coating is as low as 4 μN even under the preload force of 300 μN, showing excellent anti-crude oil-adhesion property. The PP membrane modified by the new coating possesses ultrahigh water flux (10384 L m-2 h-1 bar-1) and can realize highly efficient separation of oil-in-water emulsion (above 99%). This work is expected to accelerate the practical application of TA-APTES coating.

中文翻译：

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改性TA-APTES涂层：一步法赋予多孔膜均匀、持久的超亲水性和出色的抗原油粘附性能

摘要 鞣酸（TA）-氨基丙基三乙氧基硅烷（APTES）涂层具有优异的亲水性，可应用于多种材料。但在空中稳定性较差。为了提高其稳定性，我们在之前的工作中开发了 TA-APTES-Fe(III) 涂层，但仍然存在一些问题，如步骤繁琐，抗原油附着性能不理想等。此外，TA -APTES和TA-APTES-Fe(III)涂层不能实现多孔聚丙烯(PP)膜内表面的亲水改性。为了解决上述问题，我们在本研究中通过一步法开发了超亲水且稳定的 TA-APTES-原硅酸四乙酯 (TEOS) 涂层。新型涂层可实现PP多孔膜内表面的超亲水改性，并赋予PP膜良好的透水性，这是我们之前报道的TA-APTES和TA-APTES-Fe(III)涂层无法实现的。此外，通过引入来自TEOS的稳定醇羟基，大大提高了涂层的稳定性，得到的改性膜即使在储存后仍能保持超亲水（CA约0°）和水下超疏水（水下油CA高于150°）。空气6个月以上，超声波处理10分钟，或水洗24小时（3000r/min），表现出突出的稳定性。更重要的是，即使在300 μN的预紧力下，新涂层的原油粘附力也低至4 μN，表现出优异的抗原油粘附性能。新涂层改性的PP膜具有超高水通量（10384 L m-2 h-1 bar-1），可实现水包油乳液的高效分离（99%以上）。这项工作有望加速 TA-APTES 涂层的实际应用。