Backbone degradable polymers are attractive in a host of applications, including drug delivery, tissue engineering and fabricating semiconductors and recyclable materials. Historically, ring-opening polymerizations through radical, anionic, cationic, or organo-catalyzed mechanisms have been adopted to fabricate polymers with degradable linkages. Recently, ring-opening metathesis polymerization (ROMP) has gained increasing attention for the production of such materials due to the excellent functional group tolerance and mild reaction conditions. Herein, we have demonstrated that at low reaction temperatures, we were able to achieve controlled polymerization of an otherwise non-polymerizable, low ring-strain diazaphosphepine-based cyclic olefin (PTDO). The resulting polymer readily underwent degradation in acidic conditions via the cleavage of the acid-labile phosphoramidate linkages. PTDO was compatible in random and block copolymerizations with various norbornenes, introducing partial or complete degradability into the polymeric backbones. When oligo(ethylene glycol) bearing norbornene was used as comonomer, we generated amphiphilic copolymers that could self-assemble into micellar nanoparticles that showed no discernable cell cytotoxicity. Current research efforts have been focused on ROMP of PTDO with different functional groups and its application in drug delivery.

Degradable polyphosphoramidate via ring-opening metathesis polymerization

ACS Spring Meeting 2021

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