Zwitterionic Gradient Double‐Network Hydrogel Membranes with Superior Biofouling Resistance for Sustainable Osmotic Energy Harvesting

• Published in: Advanced functional materials 2023-05, Vol.33 (19), p.n/a
• Main Authors: Huang, Kang‐Ting, Hung, Wen‐Hsin, Su, Yu‐Chun, Tang, Fu‐Cheng, Linh, Lam Dieu, Huang, Chun‐Jen, Yeh, Li‐Hsien
• Format: Article
• Language: English
• Subjects: Acrylamide; Biocompatibility; biocompatible membranes; Biofouling; Biomimetics; Energy conversion; Energy harvesting; Fluidics; Hydrogels; ion current rectification; Ion transport; Materials science; Mechanical properties; Membranes; Nanofluids; Photopolymerization; Renewable energy; salinity gradient power; Seawater; Transport properties; Zwitterions
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202211316

Developing ion‐selective membranes with anti‐biofouling property and biocompatibility is highly crucial in harvesting osmotic energy in natural environments and for future biomimetic applications. However, the exploration of membranes with these properties in osmotic energy conversion remain largely unaddressed. Herein, a tough zwitterionic gradient double‐network hydrogel membrane (ZGDHM) with excellent biofouling resistance and cytocompatibility for sustainable osmotic energy harvesting is demonstrated. The ZGDHM, composed of negatively charged 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) as the first scaffold network and zwitterionic sulfobetaine acrylamide (SBAA) as the second network, is prepared by a two‐step photopolymerization, thus creating continuous gradient double‐network nanoarchitecture and then remarkably enhanced mechanical properties. As verified by the experiments and simulations, the gradient nanoarchitecture endows the hydrogel membrane with apparent ionic diode effect and space‐charge‐governed transport property, thus facilitating directional ion transport. Consequently, the ZGDHM can achieve a power density of 5.44 W m−2 by mixing artificial seawater and river water, surpassing the commercial benchmark. Most importantly, the output power can be promoted to an unprecedented value of 49.6 W m−2 at the mixing of salt‐lake water and river water, nearly doubling up most of the existing nanofluidic membranes. This study paves a new avenue toward developing ultrahigh‐performance osmotic energy harvesters for biomimetic applications. A tough zwitterionic gradient double‐network hydrogel membrane, with excellent biofouling resistance, cytocompatibility, and high energy conversion efficiency is exploited for sustainable osmotic energy harvesting. Due to the induced ion diode effect, low interfacial ion transport resistance, and space‐charge‐governed transport property from the continuous gradient nanoarchitecture, an amazingly high power density of up to 49.6 W m−2 is achieved.