Abstract We developed two-step thermoresponsive membranes that have two different lower critical solution temperatures. To achieve this, poly(2-dimethylaminoethyl methacrylate)-block-poly(N-isopropylacrylamide) (PDMAEMA-b-PNIPAM, PDN) was introduced into a polyethersulfone (PES) ultrafiltration membrane. The combined Fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, attenuated total reflection Fourier-transform infrared spectroscopy, and field-emission scanning electron microscopy results showed that PDN was successfully synthesized, and introduced into the PES membrane. The hydration capacity changes showed that the PES membrane with introduced PDN (PES/PDN) was temperature responsive, and that its pore structure changed. Water flux and protein separation experiments showed that the permeation properties of the PES/PDN membrane effectively changed, and protein separation was achieved based on pore structure changes in response to temperature changes. In particular, PES/PDN containing 5% PDN compared to PES separated water and three types of protein with high efficiency via three clear separation steps, at 30, 50, and 70 °C. In addition, the thermoresponsive polymer block in the PES/PDN membrane improved the flux recovery ratio from 29% to 69%.

中文翻译：

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具有可调分离特性和更高清洁效率的两步热响应膜

摘要 我们开发了两步热响应膜，具有两种不同的较低临界溶液温度。为此，将聚（2-二甲基氨基乙基甲基丙烯酸酯）-嵌段-聚（N-异丙基丙烯酰胺）（PDMAEMA-b-PNIPAM，PDN）引入聚醚砜（PES）超滤膜中。结合傅里叶变换红外光谱、核磁共振光谱、衰减全反射傅里叶变换红外光谱和场发射扫描电子显微镜结果表明，PDN 已成功合成，并被引入到 PES 膜中。水化能力的变化表明，引入 PDN (PES/PDN) 的 PES 膜具有温度响应性，并且其孔结构发生了变化。水通量和蛋白质分离实验表明，PES/PDN膜的渗透性能有效改变，基于响应温度变化的孔结构变化实现蛋白质分离。特别是，与 PES 相比，含有 5% PDN 的 PES/PDN 通过三个清晰的分离步骤在 30、50 和 70 °C 下高效分离了水和三种类型的蛋白质。此外，PES/PDN 膜中的热敏聚合物嵌段将通量回收率从 29% 提高到 69%。