Thanusing, Moki K.Pollard, Brett L.Connal, Luke A.2026-02-252026-02-25WOS:001561582200001ORCID:/0000-0001-7519-977X/work/206443767https://hdl.handle.net/1885/733806583Atmospheric water harvesting is a versatile but underutilised source of potable water. In this study, a poly(HEMA-co-PEGMA) linear copolymer and PEGDMA-crosslinked hydrogel were post-functionalised using Steglich esterification to attach l-arginine onto HEMA side chains. The water-harvesting properties of the resulting polymers were then tested. The functionalised polymers had a water uptake of 130-150 mg g−1 water after 24 hours. The thermal phase transitions were around 60-80 °C, however this can be easily adjusted by varying composition and degree of functionalisation. Notably, there was a significant decrease in the rate of water uptake after 2-3 hours. This property was further explored with a rapid cycling test, in which 70-minute water-harvesting cycles yielded 2 g water per gram of polymer after 24 hours. The data presented in this body of work showcases the water-harvesting potential of guanidinium moieties, as well as highlighting the broad scope of materials and synthetic methods that could be used for developing water-harvesting polymeric materials.This research is supported by an Australian Research Council (DP230100679) and through an Australian Government Research Training Program (RTP) Scholarship.8en© 2025 The AuthorsNetworkFilms2025-02-2410.1039/d4lp00373j105000338285