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Aligned macrocycle pores in ultrathin films for accurate molecular sieving
Nature ( IF 50.5 ) Pub Date : 2022-08-31 , DOI: 10.1038/s41586-022-05032-1
Zhiwei Jiang 1, 2 , Ruijiao Dong 1, 3 , Austin M Evans 4, 5 , Niklas Biere 6 , Mahmood A Ebrahim 1 , Siyao Li 1 , Dario Anselmetti 6 , William R Dichtel 4 , Andrew G Livingston 1, 2
Affiliation  

Polymer membranes are widely used in separation processes including desalination1, organic solvent nanofiltration2,3 and crude oil fractionation4,5. Nevertheless, direct evidence of subnanometre pores and a feasible method of manipulating their size is still challenging because of the molecular fluctuations of poorly defined voids in polymers6. Macrocycles with intrinsic cavities could potentially tackle this challenge. However, unfunctionalized macrocycles with indistinguishable reactivities tend towards disordered packing in films hundreds of nanometres thick7,8,9, hindering cavity interconnection and formation of through-pores. Here, we synthesized selectively functionalized macrocycles with differentiated reactivities that preferentially aligned to create well-defined pores across an ultrathin nanofilm. The ordered structure was enhanced by reducing the nanofilm thickness down to several nanometres. This orientated architecture enabled direct visualization of subnanometre macrocycle pores in the nanofilm surfaces, with the size tailored to ångström precision by varying the macrocycle identity. Aligned macrocycle membranes provided twice the methanol permeance and higher selectivity compared to disordered counterparts. Used in high-value separations, exemplified here by enriching cannabidiol oil, they achieved one order of magnitude faster ethanol transport and threefold higher enrichment than commercial state-of-the-art membranes. This approach offers a feasible strategy for creating subnanometre channels in polymer membranes, and demonstrates their potential for accurate molecular separations.



中文翻译:

超薄膜中对齐的大环孔用于精确的分子筛分

聚合物膜广泛用于分离过程,包括脱盐1、有机溶剂纳滤2,3和原油分馏4,5然而,亚纳米孔的直接证据和操纵其尺寸的可行方法仍然具有挑战性,因为聚合物6中定义不明确的空隙的分子波动。具有内在空腔的大环可以潜在地应对这一挑战。然而,具有无法区分的反应性的未官能化大环倾向于在数百纳米厚的薄膜中无序堆积7,8,9,阻碍空腔互连和通孔的形成。在这里,我们合成了具有不同反应性的选择性功能化大环化合物,这些大环化合物优先排列以在超薄纳米薄膜上形成明确的孔。通过将纳米膜厚度降低到几纳米来增强有序结构。这种定向结构能够直接可视化纳米膜表面中的亚纳米大环孔,通过改变大环的特性,其尺寸适合于 Ångström 精度。与无序对应物相比,对齐的大环膜提供了两倍的甲醇渗透率和更高的选择性。用于高价值分离,此处以浓缩大麻二酚油为例,他们实现了比商业最先进的膜快一个数量级的乙醇运输和三倍的富集。这种方法为在聚合物膜中创建亚纳米通道提供了一种可行的策略,并展示了它们在精确分子分离方面的潜力。

更新日期:2022-09-01
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