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Polyamide desalination membranes: Formation, structure, and properties
Progress in Polymer Science ( IF 27.1 ) Pub Date : 2021-09-05 , DOI: 10.1016/j.progpolymsci.2021.101451
Viatcheslav Freger 1, 2 , Guy Z. Ramon 1, 2, 3
Affiliation  

Empirical discovery, four decades ago, of polyamide membranes made by interfacial polymerization revolutionized large-scale desalination and has made desalinated water affordable to millions of people worldwide. The path to better understanding of the exceptional performance exhibited by these polymeric films, critical for rational membrane design and the search for alternative materials, begins from understanding their formation and the resultantmolecular and nanostructure and has posed numerous questions. The self-limited, ultra-small thickness, irregular multiscale nanostructure, and the need for polyamide films to be formed on a support rather than in a bulk process pose formidable challenges for structural characterization and molecular modeling. Further challenges arise from insufficient understanding of the relations between polymer chemistry, multi-scale structure, and their impact on transport and mechanical characteristics. Extensive research conducted over the last decades, using dedicated experimental and theoretical approaches, have highlighted many remarkable features of polyamide thin films, and yet many questions still await conclusive answers.

The present paper reviews the current state of understanding of polyamide thin films, and, in particular, fully and semi-aromatic “winner” chemistries used for membrane separation, based on recent advances in the nanoscale characterization and theoretical investigations of their formation, chemistry, structure, morphology and barrier characteristics down to the molecular scale. These are reviewed in light of the recent developments in understanding of the interfacial polymerization process, reaction, packing and crosslinking of polymeric building blocks, formation and distribution of charge groups, and interaction of the resultant polymer network with water and ions. The proposed unified picture that links the emerging picture of the multiscale nano- and molecular structure of polyamide thin films with macro-scale characteristics, enables a consistent rationalization of their superior barrier characteristics. Furthermore, such a framework provides insight on inherent weaknesses of polyamides and the challenges of overcoming these limitations and developing viable alternatives. With membranes fast becoming the choice for a growing number of challenging separations, and with the need to replace current materials with sustainable, environmentally benign alternatives, drawing on established knowledge will provide a solid foundation from which better controlled, tunable membranes can be fabricated from next-generation building blocks.



中文翻译:

聚酰胺脱盐膜:形成、结构和特性

四年前,通过界面聚合制成的聚酰胺膜的实证发现彻底改变了大规模海水淡化,并使全世界数百万人能够负担得起海水淡化。更好地了解这些聚合物薄膜表现出的卓越性能的途径,对于合理的膜设计和寻找替代材料至关重要,从了解它们的形成以及由此产生的分子和纳米结构开始,并提出了许多问题。自限性、超小厚度、不规则的多尺度纳米结构,以及需要在支撑体上而不是在本体工艺中形成聚酰胺薄膜对结构表征和分子建模构成了巨大挑战。进一步的挑战来自对聚合物化学、多尺度结构及其对传输和机械特性的影响之间的关系的理解不足。在过去的几十年中,使用专门的实验和理论方法进行的广泛研究突出了聚酰胺薄膜的许多显着特征,但仍有许多问题等待最终答案。

本文基于纳米级表征的最新进展和对其形成、化学、低至分子尺度的结构、形态和屏障特性。根据对界面聚合过程、聚合物结构单元的反应、堆积和交联、电荷基团的形成和分布以及所得聚合物网络与水和离子的相互作用的理解的最新进展,对这些进行了审查。拟议的统一图片将聚酰胺薄膜的多尺度纳米和分子结构的新兴图片与宏观尺度特征联系起来,能够对其卓越的阻隔特性进行一致的合理化。此外,这样的框架提供了对聚酰胺固有弱点以及克服这些限制和开发可行替代品的挑战的洞察。随着膜迅速成为越来越多具有挑战性的分离的选择,并且需要用可持续的、环境友好的替代品替代当前的材料,利用已有的知识将提供一个坚实的基础,从中可以制造出更好的控制、可调谐的膜。 -生成构建块。

更新日期:2021-09-23
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