Tough, Anti-Swelling Supramolecular Hydrogels Mediated by Surfactant–Polymer Interactions for Underwater Sensors

Abstract

It is a great challenge for traditional hydrogel-based sensors to be effective underwater due to unsatisfactory water resistance and insufficient wet adhesion. Herein, a tough supramolecular hydrogel aiming at underwater sensing is prepared by the modification of hydrophilic poly­(acrylic acid) (PAA) with a small amount of hydrophobic lauryl methacrylate (LMA) in the presence of high concentrations of the cationic surfactant cetyltrimethylammonium bromide (CTAB). Owing to the synergistic effects of the electrostatic interactions and hydrophobic associations of CTAB with the P­(AA-co-LMA) copolymer, the hydrogel with a water content of approximately 58.5 wt % demonstrates outstanding anti-swelling feature, superior tensile strength (≈1.6 MPa), large stretchability (>900%), rapid room-temperature self-recovery (≈3 min at 100% strain), and robust wet adhesion to diverse substrates. Moreover, the strain sensor based on the hydrogel displays keen sensitivity in a sensing range of 0–900% (gauge factor is 0.42, 3.44, 5.44, and 7.39 in the strain range of 0–100, 100–300, 300–500, and 500–900%, respectively) and pronounced stability both in air and underwater. Additionally, the hydrogel can be easily recycled by dissolving in anhydrous ethanol. This work provides a facile strategy to fabricate eco-friendly, tough supramolecular hydrogels for underwater sensing.

A novel triple-network hydrogel based on borate ester groups: from structural modulation to rapid wound hemostasis

“…However, non-covalent cross-linked hydrogel materials contain a large number of dynamic chemical bonds, [5][6][7][8][9] to effectively achieve a perfect fit between the hydrogel and the wound, 10 and their self-adaptive ability is significantly improved. 11 In addition, non-covalent cross-linked hydrogel materials have a wide range of applications in intelligent sensing, 12,13 biomedicine 14 and other fields.…”

Wet-Adhesive Multifunctional Hydrogel with Anti-swelling and a Skin-Seamless Interface for Underwater Electrophysiological Monitoring and Communication

“…The ability for wet/underwater adhesion is essential for skininterfaced hydrogels owing to the inevitable exposure to aqueous environments (e.g., sweating, raining, bathing, and swimming), notably for the monitoring of swimmers' body motions, and it is of great value to detect real-time bioelectrical signals underwater for safety of underwater operations. 1 For instance, heart attacks have risen to the second ranking cause of death for divers, which makes aquatic electrocardiogram (ECG) monitoring crucial before a heart attack occurs. 2 Nevertheless, conventional adhesive hydrogels that are applied in a dry environment are not suitable for adhesion in these aquatic conditions because water prevents direct contact between the sensor and the skin.…”

Supramolecular Hydrogel Dressing: Effect of Lignin on the Self-Healing, Antibacterial, Antioxidant, and Biological Activity Improvement

“…The supramolecular interaction is a general term for a class of intermolecular interactions . The supramolecular interactions mainly include hydrophobic interactions, − host–guest interactions, hydrogen bonds, crystallization, electrostatic interactions, and multiple intermolecular interactions. − These interactions exist between molecules, oligomers, or polymer chains. Compared to traditional chemical cross-linking hydrogels, the supramolecular hydrogel with self-healing properties has extremely outstanding advantages in the clinical wound management field.…”