Tough, adhesive and conductive polysaccharide hydrogels mediated by ferric solution

In general, chitosan should be dissolved in strong acidic media (such as acetic acid) before it could be applied as hydrogels. However, it was found that chitosan could also be dissolved in the ferric solution to form ferric-chitosan complex via coordination interaction. Subsequently, the ferric-chitosan complex was successfully introduced into the hydrogel system to obtain tough, adhesive and conductive chitosan-polyacrylamide double network (CS-PAAm DN) hydrogels. Surprisingly, CS-PAAm DN hydrogel could repeatedly adhere to various solid materials and biological tissues through physical interactions. The maximum peeling force was 256 N/m on the aluminum surface. Moreover, the hydrogel exhibited adequate mechanical performance (135 kPa, 2332%). And the introduction of ferric chloride could also endow the hydrogel with conductive performance. As a result, the strategy based on tough, adhesive and conductive polysaccharide hydrogels mediated by ferric solution would broaden the path to fabricate a new generation of soft materials for wide applications.