Tough and self‐healable carrageenan‐based double network microgels enhanced physical hydrogels for strain sensor

Abstract

Double network hydrogels (DN gels) demonstrate extremely high strength and toughness; however, conventional DN gels are fully chemically crosslinked, which are often softening and lack self-healing. Here, a new type of fully physical DN (P-DN) gels, that is, K + ions crosslinked κ-carrageenan (K + C) microgel (MG) composite hydrophobically crosslinked polyacrylamide (HPAAm) gels or K + C-MG/HPAAm gels, in which the HPAAm gel was physically crosslinked by hydrophobic interactions as well as topologically crosslinked by P-DN microgels, were prepared by a facile one-pot method. At the optimal condition, K + C-MG/HPAAm gel exhibited high strength (0.36 MPa) and high toughness (968 J/m 2 ). In addition, it can rapidly recover from softening and display good fatigue resistance. Notably, K + C-MG/HPAAm gel also demonstrated selfhealing properties on account of its physical nature. Because there are anionic κ-carrageenan and KCl, K + C-MG/HPAAm gels are ionic conductive, which were used as strain sensors to monitor the human motions. We believe our K + C-MG/HPAAm gels provide a new insight in the field of DN gels.

Stretch Sensor: Development of Biodegradable Film

“…Gels respond to repeated mechanical stimuli by increasing their polymer content and size and gaining more strength, similar to skeletal muscle growth induced by normal physical exercise. They applied programmed mechanical stimuli to DN gels fed the corresponding functional monomers [ 31 ].…”

Recent developments of polysaccharide‐based double‐network hydrogels

“…Carrageenan (CG) is a family of anionic sulphated polysaccharides obtained from red seaweeds, composed of β-1,3-linked D-galactose and α-1,4-linked D-galactose, and substitutions such as ester sulfate or 3, 6-anhydride on the 4-linked residue. 93 Differ from the number and position of ester sulfate groups and the content of 3,6-galactose, it could be divided into six types (i.e. Kappa, Iota, Lambda, Mu, Nu, and Theta).…”

Role of hierarchy structure on the mechanical adaptation of self-healing hydrogels under cyclic stretching

“…Mechanically induced nanofiber and nanocrystallization systems are examples of physical mechanisms (9)(10)(11). Although they are closed systems that do not exchange substances with their surroundings, the mechanical adaptation phenomena occurred during cyclic stretching of synthetic hydrogels, such as shakedown (12)(13)(14), fatigue (14)(15)(16)(17)(18)(19)(20)(21)(22)(23), and self-recover (24)(25)(26)(27)(28)(29)(30), also occur in muscles and tendons during daily activities like walking, running, throwing, climbing, and lifting heavy loads. However, there is a lack of understanding regarding the effects of cyclic stretching on the structural evolution and correlated dynamics of mechanical adaptation in synthetic hydrogels, especially those with hierarchical structures.…”