Yu C.-HChiang P.-YYI-CHEUN YEH2022-03-222022-03-22202117599954https://www.scopus.com/inward/record.uri?eid=2-s2.0-85120043053&doi=10.1039%2fd1py01325d&partnerID=40&md5=a59b88b53492635bfb1bfdeef0a2ca6bhttps://scholars.lib.ntu.edu.tw/handle/123456789/600421A new class of metallo-hydrogels has been developed using di(2-picolyl)amine (DPA)-functionalized 4-arm polyethylene glycol (4A-PEG-DPAn) polymers crosslinked by metal-ligand coordination. The number of the DPA group per polymer core was controlled to prepare 4A-PEG-DPAn polymers with n = 4 or 8. The 4A-PEG-DPAn polymers were crosslinked using four metal ions (i.e., Ni2+, Co2+, Cu2+, and Zn2+) to form 4A-PEG-DPAn (M2+) hydrogels. The 4A-PEG-DPA8 (M2+) hydrogels presented denser networks and longer relaxation times than the 4A-PEG-DPA4 (M2+) hydrogels, indicating the number of the DPA group per polymer core played a dominant role in determining the crosslinked network and the properties. The 4A-PEG-DPA8 (Ni2+) hydrogels possessed the most highly crosslinked network among the four types of 4A-PEG-DPA8 (M2+) hydrogels due to the strong binding affinity between DPA and Ni2+ ions. Given the dynamic DPA-M2+ coordination crosslinks in the network, 4A-PEG-DPAn (M2+) hydrogels were capable of stimuli-responsiveness (i.e., pH, temperature, and redox), self-healing, shear-thinning, and injectability. Taken together, we have demonstrated that the microstructures and properties of 4A-PEG-DPAn (M2+) hydrogels can be tailored by controlling the number of the DPA group per polymer core as well as the choice of metal ions, showing great potential for specific applications. This journal is ? The Royal Society of Chemistry.Binding energyHydrogelsLigandsMetal ionsMetalsShear thinning4-arm polyethylene glycolsBinding affinitiesCrosslinkedCrosslinked networksDense networkFunctionalizedLigand coordinationMetal ligandsPropertyStrong bindingPolyethylene glycolsjournal article10.1039/d1py01325d2-s2.0-85120043053