Zwitterions of charge-balanced units have super-low fouling properties induced by ionic solvation, but their extensive applications in polymeric substrates are strictly constrained by current constructing strategies. A zwitterion-like, charge-balanced ultrathin layer with high antifouling capacity was covalently constructed on delicate aromatic polyamide (PA) reverse osmosis (RO) membranes via a mild and solvent-free grafting-to strategy. Two oppositely charged commercial short-chain carbonyl alkenes, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and methacryloxyethyltrimethylammonium chloride (DMC), were directly mixed-grafted with amino groups on PA RO membrane surface via Michael addition. Under ambient temperature and pressure, these oppositely charged compounds were assembled into a zwitterion-like, charge-balanced ultrathin layer. The dynamic fouling experiments indicated that the modified membrane exhibited strong antifouling properties and excellent permeation recovery abilities. Surface characterization revealed that the selective layer thickness and surface roughness were not measurably changed. More meaningful is that the typical ridge-and-valley surface structure and the excellent separation performance were both well preserved after modification. This opens a universal avenue to construct a zwitterion-like, ultrathin antifouling layer on the delicate polymer substrate without compromising its original matrix structure and performance, which has promising application in areas of biosensors, tissue engineering, and biomaterials.

中文翻译：

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聚合物膜上的两性离子状电荷平衡超薄层，具有防污性能

电荷平衡单元的两性离子具有由离子溶剂化引起的超低结垢性能，但是它们在聚合物基材中的广泛应用受到当前构造策略的严格限制。通过温和且无溶剂的接枝策略，在精致的芳香族聚酰胺（PA）反渗透（RO）膜上共价构建了具有高防污能力的两性离子状，电荷平衡的超薄层。通过迈克尔加成反应，将两种带相反电荷的商业短链羰基烯烃，2-丙烯酰胺基-2-甲基丙烷磺酸（AMPS）和甲基丙烯酰氧基乙基三甲基氯化铵（DMC）直接与氨基混合在PA RO膜表面。在环境温度和压力下，这些带相反电荷的化合物组装成两性离子状，电荷平衡的超薄层。动态结垢实验表明，改性膜具有很强的防污性能和优异的渗透恢复能力。表面表征表明，选择性层的厚度和表面粗糙度没有可测量的变化。更有意义的是，经过改性后，典型的脊和谷表面结构和出色的分离性能都得到了很好的保留。这为在脆弱的聚合物基材上构建类似两性离子的超薄防污层提供了一条通用途径，而不会损害其原始基质结构和性能，这在生物传感器，组织工程和生物材料领域具有广阔的应用前景。