Construction and Properties of Double‐Crosslinked Hydrogels Based on Host–Guest Interactions/UV Polymerization

Abstract

AbstractSupramolecular hydrogels based on host–guest interactions have inherent flaw that the host molecules easily slide on or fall off the linear guest molecules, causing collapse of the networks. Hence, a double‐crosslinking strategy is introduced in this study. The primary crosslinking formed via host–guest interactions between α‐cyclodextrin (α‐CD) and poly(ethylene glycol) dimethacrylate (PEGDMA) or between α‐CD and four‐arm poly(ethylene glycol) methacrylate (4arm PEG‐MA). Then, secondary networks among PEGDMA or 4arm PEG‐MA formed via UV‐induced crosslinking. Results show that the fracture stress and fracture strain of PEGDMA‐α‐CD double‐crosslinked hydrogels (P‐C‐U) increases up to 0.63 MPa and 71%, respectively, which significantly affected by molecular weight of PEGDMA. The double‐crosslinking strategy helps increase the toughness up to 12.9 MJ m−3 (P6k‐0.025M‐C‐U) and 17.23 MJ m−3 (4P10k‐0.025M‐C‐U), as well as impart a certain degree of fatigue resistance to both PEGDMA hydrogels and 4arm‐PEG‐MA hydrogels, which is believed to be due to the energy dissipation mechanism introduced in the structure. The swelling capacity of double‐crosslinked hydrogels is decreased compared to that with single‐UV‐crosslinked hydrogels, may be because the double‐crosslinking strategy increases the crosslinking density of the hydrogel structure. In addition, both the molecular weight and concentration of PEGDMA and 4arm‐PEG‐MA influences the swelling capacity of the double‐crosslinked hydrogels.