Kinetic trapping of 3D-printable cyclodextrin-based poly(pseudo)rotaxane networks

Synthetically trapping kinetically varied (super)structures of molecular assemblies and amplifying them to the macroscale is a promising, yet challenging, approach for the advancement of meta-stable materials. Here, we demonstrated a concerted kinetic trapping design to timely resolve a set of transient polypseudorotaxanes in solution and harness a crop of them via micro-crystallization. By installing stopper or speed bump moieties on the polymer axles, meta-stable polypseudorotaxanes with segmented cyclodextrin blocks were hierarchically amplified into crystalline networks of different crosslinking densities at mesoscale and viscoelastic hydrogels with 3D-printability in bulk. We demonstrated simultaneous 3D-printing of two polypseudorotaxane networks from one reactive ensemble and their conversion to heterogeneous polyrotaxane monoliths. Spatially programming the macroscale shapes of these heterogeneous polyrotaxanes enabled the construction of moisture-responsive actuators, in which the shape morphing originated from the different numbers of cyclodextrins interlocked in these polyrotaxane networks.