Janus Nanoparticle Coupled Double-Network Hydrogel.

For double network (DN) hydrogels, their performance can be tuned by adjusting the interaction between their two networks. A novel DN hydrogel toughening approach is proposed by employing Janus nanoparticles (JNs) as crosslinkers to gain a conjoined-network hydrogel. First, a kind of JNs modified by amino groups and quaternary ammonium salt is synthesized, named R3 N+ -JN-NH2 . The DN hydrogel is fabricated based on ionic coordination between calcium chloride (CaCl2 ) and sodium alginate (Alg), as well as covalent (benzoic imine) between glycol chitosan (GC) and benzaldehyde-capped poly(ethylene oxide) (BzCHO-PEO-BzCHO). Based on the same covalent and ionic dynamic crosslinking mechanism, the added R3 N+ -JN-NH2 interacts with two networks to promote crosslinking to form a dually crosslinked structure. The R3 N+ -JN-NH2 effectively provides more energy dissipation, and the hydrogel with conjoined networks shows better compression resistance.