Internal and External Strategies for Preventing Hydrogel Dehydration

ABSTRACT Hydrogel dehydration compromises their functionality in applications ranging from flexible electronics to biomedical devices. This review systematically examines strategies to enhance hydrogel hydration stability, which are categorized into internal modifications and external encapsulation. Internally, these approaches include incorporating ionic compounds (e.g., LiCl) to strengthen ion‐dipole interactions with water and convert free water into the bound state; introducing organic solvents (e.g., glycerol, ethylene glycol) to form hydrogen‐bonded networks that reduce water mobility; embedding hydrophilic inorganic additives (e.g., SiO 2 , MXene) to anchor water molecules and modify the network architecture; designing multicomponent systems for synergistic water retention; and implementing a “hydro‐locking” mechanism to immobilize water molecules within the polymer network, thereby achieving exceptional thermal resilience. Externally, encapsulation strategies utilize hydrophobic barriers such as silicone rubbers (e.g., PDMS), which offer facile processability but limited long‐term effectiveness; carbon‐based elastomers (e.g., SIBS), which provide excellent barrier properties but pose challenges for robust interfacial adhesion due to their chemical inertness; and self‐healing organic layers (e.g., lipids, silicone oil), which often suffer from inherent permeability and potential leakage. A critical challenge for encapsulation is that it often introduces mechanical mismatch and impedes mass transport, limiting its applicability in fields like drug delivery. Future efforts shall prioritize integrated designs that reconcile dehydration resistance with mechanical compliance, functionality, and mass‐transfer requirements for next‐generation hydrogel devices.