Yuwei Gu1, Eric A. Alt1, Heng Wang2, Xiaopeng Li2, Adam P. Willard1, Jeremiah A. Johnson1*1Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139

2 Department of Chemistry, University of South Florida, Tampa 33620

Polymer network topology

As a global parameter for polymer networks, network topology dictates avariety of material properties, ranging from static properties to networkdynamics.

Photoswitching polymer network topology

Photoswitching metal-organic cage

• Topology switching enables the materials to switch between low-modulus and high-modulus states.• Topology switching is characterized by small angle X-ray scattering (SAXS), wherein d is junction-to-

junction distance, r is the radius of the MOC-based junction.

Characterization of topology switching

• The abundancy of primary loops changes dramatically upon topology switching.• By doping free ligands as “defects”, the storage modulus of the material can be switched by one

order of magnitude as the material switches its degree of defect-tolerance upon topology switching.

Switching of defect-tolerance Fatigue properties

Switching of network dynamics Conditional self-healing properties Conclusion• Introducing a photo-switchable metal-organic cage in polymer gels, for thefirst time we realized externalswitching of network topology.

• Switching network topology enablesthe material to switch between twostates that have completely differentstatic and dynamic properties.

References1. Gu, Y. et al. Trends Chem. 2019, 1, 318-334.2. Gu, Y. et al. Nature 2018, 560, 65-69.3. Gu, Y et al. Proc. Natl. Acad. Sci. U.S.A.2017, 114, 4875-4880.4. Han, M. et al. Angew. Chem. Int. Ed.2016, 55, 445-449.5. Zhukhovitskiy, A. V. et al. Nat. Chem.2016, 8, 33-41.