Photocrosslinking the polystyrene core of block-copolymer nanoparticles

Abstract

The crosslinking of the core of nanoparticles composed of polystyrene-block-poly(ethylene oxide) copolymers can be achieved through encapsulation of a small molecule aryl diazide, 4,4′-diazidobiphenyl, and subsequent photolysis. The core-crosslinked nanoparticles exhibited high stability under thermal challenge. These stabilized nanoparticles have potential to serve as a nanobead for the polymerase chain reaction (PCR). We also demonstrated that this crosslinker can endow thin films of polystyrene with solvent resistance. NMR studies on these films provided evidence that crosslinking was occurring viainsertion of the nitrene formed by photolysis of the azide into the methylene or methine groups in the backbone of polystyrene.