Zipping Polymers into Nanoparticles via Intrachain Alternating Radical Copolymerization

The synthesis of single‐chain nanoparticles (SCNP) via the intrachain radical homopolymerization and alternating copolymerization of pendant styrene or stilbene units is reported. In the presence of a radical initiator, styrene‐functionalized polymers undergo intrachain cross‐linking to form SCNP; however, when an electron deficient monomer such as maleic anhydride is added, interchain coupling occurs. For the stilbene‐functionalized polymer, no homopolymerization of pendant stilbene units is observed, but copolymerization initiated in the presence of maleic anhydride or N‐ethyl maleimide results in nanoparticle formation. Fluorescent SCNP are synthesized using N‐(1‐pyrene)maleimide. Stilbene is known to undergo alternating copolymerization with these electron‐deficient monomers, providing a new method for synthesizing cross‐linked particles with simple alternating sequences while simultaneously installing functionality and tuning the particle size and density. Functional single‐chain nanoparticles are synthesized from the intramolecular cross‐linking of linear poly(styrene‐co‐divinylbenzene) using radical polymerization and poly(styrene‐co‐(4‐vinylstilbene)) using the alternating radical copolymerization with electron‐deficient monomers, including maleic anhydride, N‐ethyl maleimide, and N‐(1‐pyrene) maleimide.