Confined Water Dominates Ion/Molecule Transport in Hydrogel Nanochannels
Peijia Li, Xiaotao Yang, Fengxiang Chen, Dianyu Wang, Dezhao Hao, Zhe Xu, Ming Qiu, Shaofan He, Fan Xia, Ye Tian
Abstract
Current artificial nanochannels rely more on charge interactions for intelligent mass transport. Nevertheless, popular charged nanochannels would lose their advantages in long-term applications. Confined water, an indispensable transport medium in biological nanochannels, dominating the transport process in the uncharged nanochannels perfectly provides a new perspective. Herein, we achieve confined-water-dominated mass transport in hydrogel nanochannels (HNCs) constructed by in situ photopolymerization of acrylic acid (PAA) hydrogel in anodic alumina (AAO) nanochannels. HNCs show selectivity to Na + transport and a high transport rate of molecules after introducing Na + /Li +, compared with other alkali metal ions like Cs + /K + . The mechanism given by ATR-FTIR shows that the hydrogen-bonding structure of confined water in HNCs is destabilized by Na + /Li +, which facilitates mass transport, but is constrained by Cs + /K +, resulting in transport inhibition. This work elucidates the relationship between confined water and mass transport in uncharged nanochannels while also presenting a strategy for designing functional nanochannel devices.