Ji Chenhao, Xue Shuangmei, Lin Cheng-Wei, Mak Wai H, McVerry Brian T, Turner Chris L, Anderson Mackenzie, Molas Jenna C, Xu Zhenliang, Kaner Richard B
Department of Chemistry and Biochemistry and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States.
Department of Chemical Engineering, East China University of Science and Technology, Shanghai 200237, China.
ACS Appl Mater Interfaces. 2020 Jul 8;12(27):30796-30804. doi: 10.1021/acsami.0c06639. Epub 2020 Jun 29.
Thin-film composite (TFC) membranes are favored for precise molecular sieving in liquid-phase separations; they possess high permeability due to the minimal thickness of the active layer and the high porosity of the support layer. However, current TFC membrane fabrication techniques are limited by the available materials for the selective layer and do not demonstrate the level of structural control needed to substantially advance organic solvent nanofiltration (OSN) membrane technology. In this work, we employ the newly developed thin-film lift-off (T-FLO) technique to fabricate polybenzimidazole (PBI) TFC membranes with porous support layers uniquely tailored to OSN. The drop-cast dense PBI selective layers endow the membranes with an almost complete rejection of common small dye molecules. The polymeric support layer is optimized by a combinatorial approach using four different monomers that alter the cross-linking density and polymer chain flexibility of the final composite. These two properties substantially affect the porogen holding capacity of the reticular polymer network, leading to the formation of different macropore structures. With a 150 nm thick PBI selective layer and fine-tuning of the support layer, the resulting membrane achieves stable and superior permeance of 14.0, 11.7, 16.4, 11.4, 17.1, and 19.7 L m h bar for water, ethanol, methanol, isopropanol, tetrahydrofuran (THF), and acetonitrile, respectively.
薄膜复合（TFC）膜因其在液相分离中能够实现精确的分子筛分而受到青睐；由于活性层厚度极小且支撑层孔隙率高，它们具有高渗透性。然而，目前的TFC膜制备技术受到选择性层可用材料的限制，并且无法展现出大幅推进有机溶剂纳滤（OSN）膜技术所需的结构控制水平。在这项工作中，我们采用新开发的薄膜剥离（T-FLO）技术来制备具有专门为OSN定制的多孔支撑层的聚苯并咪唑（PBI）TFC膜。滴铸致密的PBI选择性层使膜几乎能完全截留常见的小染料分子。聚合物支撑层通过使用四种不同单体的组合方法进行优化，这些单体可改变最终复合材料的交联密度和聚合物链柔性。这两个特性极大地影响了网状聚合物网络的致孔剂容纳能力，导致形成不同的大孔结构。通过150纳米厚的PBI选择性层以及对支撑层的微调，所得膜对水、乙醇、甲醇、异丙醇、四氢呋喃（THF）和乙腈的稳定且优异的渗透率分别达到14.0、11.7、16.4、11.4、17.1和19.7 L m⁻² h⁻¹ bar⁻¹。
