Figure 1.

Network structure of AFCT-based photodegradable hydrogels. a Structures of the cyclooctyne functionalized PEG macromer, PEG-4DBCO, and the azide functionalized crosslinkers, AS-AA, AS-PA, AS-PhAA containing the allyl sulfide functionality. b Upon mixing, the strained octyne reacts with the azide to form a bond through strain-promoted azide alkyne cycloaddition (SPAAC), resulting in the formation of a hydrogel network incorporating the allyl sulfide functionalities. c The evolution of shear storage (black) and loss (gray) moduli are monitored with shear rheology for AS-PA (solid line), AS-AA (dotted), and AS-PhAA (dashed) crosslinkers. Hydrogels reach a similar shear modulus after 10 minutes. d A frequency sweep of the shear storage (black) and loss (gray) moduli for AS-PA (solid line), AS-AA (dotted), and AS-PhAA (dashed) crosslinked hydrogels shows a lack of frequency dependence, indicative of elastic networks.