Two-Step Thermoresponsive Ultrafiltration Membranes from Polymerization of Lyotropic Liquid Crystals
Two-Step Thermoresponsive Ultrafiltration Membranes from Polymerization of Lyotropic Liquid Crystals
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DOI：
10.1021/acsapm.2c01095
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发表时间：
2022-10
影响因子：
5
通讯作者：
Younes Saadat;K. Kim;R. Foudazi
中科院分区：
文献类型：
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作者：
Younes Saadat;K. Kim;R. Foudazi
在这项研究中，我们提出了一个两步温敏超滤（UF）膜通过聚合的溶致液晶（LLC）的制造。使用市售Pluronic F127嵌段共聚物、水（含有过硫酸铵作为引发剂）和可聚合油（丙烯酸正丁酯/二甲基丙烯酸乙二醇酯）的混合物来产生具有层状结构的LLC，如通过交叉偏振光显微镜和原子力显微镜表征的。采用差示扫描量热法评价聚合LLC（polyLLC）的温敏行为。由于F127的较低临界溶解温度（LCST）和F127表面活性剂的聚环氧乙烷（PEO）链的晶体结构的熔融，观察到polyLLC的两步热响应性（1035 ° C和1050 °C）。在下一步骤中，将所获得的中间相流延在非织造聚酯支撑片材上，随后进行热聚合。在不同温度下对膜的水化能力、水通量、结垢后水通量恢复和截留分子量（MWCO）进行评价，以考察其热响应性。实验结果表明，超滤膜在聚乳酸的LCST和PEO熔融温度下具有可逆的温敏行为。此外，污染膜的清洁效率可以通过使用其温敏特性来提高，从而延长产品的使用寿命。此外，由于孔径随温度刺激而变化，膜的MWCO可随温度而改变。
In this study, we present the fabrication of a two-step thermoresponsive ultrafiltration (UF) membrane through polymerization of a lyotropic liquid crystal (LLC). A mixture of commercially available Pluronic F127 block copolymer, water (containing ammonium persulfate as the initiator), and polymerizable oil (n-butyl acrylate/ethylene glycol dimethacrylate) is used to create an LLC with a lamellar structure, as characterized by cross-polarized light microscopy and atomic force microscopy. Differential scanning calorimetry is employed to evaluate the thermoresponsive behavior of the polymerized LLC (polyLLC). Two-step thermoresponsiveness (∼35 and ∼50 °C) of the polyLLC is observed due to the lower critical solution temperature (LCST) of F127 and melting of the crystalline structure of the polyethylene oxide (PEO) chains of the F127 surfactant. In the next step, the obtained mesophase is cast on a nonwoven polyester support sheet followed by thermal polymerization. The hydration capacity, water flux, water flux recovery after fouling, and molecular weight cutoff (MWCO) of the obtained membrane are evaluated at different temperatures to examine its thermoresponsiveness. The experimental results reveal that the UF membrane has a reversible thermoresponsive behavior at the LCST and PEO melting of polyLLC. Additionally, the cleaning efficiency of the fouled membrane can be enhanced by using its thermoresponsive behavior, resulting in an extended lifetime of the product. Furthermore, the MWCO of the membrane can be altered with temperature due to the pore size change with temperature stimulus.