Single-Chain Knot/Cyclized Polymers from Controlled Multivinyl Monomer Polymerisation and Their Biomedical Applications

Classical theory has long claimed that the polymerizations of multi-vinyl monomers (MVM) lead to insoluble cross-linked materials, as defined by P. Flory and W. Stockmayer 80 years ago (F-S theory). Therefore, the (homo)polymerization of MVMs is still considered as a formidable task in chain growth polymerization. We first proposed a deactivation enhanced ATRP (DE-ATRP) method to homopolymerize MVMs. This approach has broken through two barriers for the polymerization of MVMs: uncontrollable homopolymerization and highly diluted reaction conditions, and successfully achieved the controlled homopolymerization of MVMs in concentrated conditions. Via this approach, a new class of single-chain knot/cyclized polymers can be formed due to the enhanced promotion of intramolecular cyclization and the suppression of intermolecular crosslinking. Our breakthrough lies in the ability to alter the growth manner of polymerization by controlling the kinetic chain length together with manipulating chain growth conditions to achieve different polymer structures, which opened an efficient and practical road for the design and synthesis of knot/cyclized polymers from economical available monomers. The produced knot/cyclized polymeric materials have demonstrated the great potentials in biomedical applications.