Arm-degradable star polymers with crosslinked ladder-motif cores as a route to soluble microporous nanoparticles

We report a strategy to synthesize controlled star polymers with cores consisting of crosslinked (macro)molecular ladder motifs. In this strategy, living ROMP of norbornenes or norbornene-terminated macromonomers was used to produce arms followed by crosslinking using ladder-shaped dinorbornenes or norbornene-terminated ladder polymers to form star polymers. When degradable grafted arms were used, the cores can be isolated as soluble polymeric nanoparticles upon arm degradation. We demonstrated the presence of microporosity from the crosslinked ladder core of star polymers. This strategy provides access to a new class of soluble and stable microporous polymeric nanoparticles.