Building covalent crosslinks of carboxymethyl konjac glucomannan with boronic ester bonds for fabricating multimodal hydrogel sensor.

As the derivative of konjac glucomannan (KGM), carboxymethyl konjac glucomannan (CMK) has attracted increasing attention in the polysaccharide hydrogel fields with the aim of improving the performance related to drug delivery and release. In this study, we prepared a CMK-based hydrogel with dual characteristic crosslinks, and unlocked new applications of this type of hydrogel in soft sensor fields. CMK and poly (vinyl alcohol) were used as substrates, and physical crosslinks were constructed via the freeze-thawing treatments and covalent crosslinks were built via the boronic ester bonding. As-prepared hydrogel possessed significantly improved mechanical performance because the boronic ester bonding, on the one hand, well associated the two kinds of polymer chains, and on the other hand, played the role of 'sacrificial crosslinks'. Furthermore, the occurrence of dynamic boronic ester bonding gave the hydrogel strain- and temperature-sensitive ionic conductivity, and therefore, the hydrogels could be used to identify human motions and as-resulted environmental temperature alterations, and worked well in various scenarios. This work activates new application of CMK in the multimodal sensing field, and also proposes an intriguing way of building multiple crosslinks in the KGM derivative-based hydrogels.