Photodimerization as an alternative to photocrosslinking of nanoparticles: proof of concept with amphiphilic linear polyoxazoline bearing coumarin unit

Photosensitive amphiphilic linear polyoxazolines (CoumC₁₁–POx_n) bearing alkyl chain decorated by a UV-active coumarin end group have been synthesized by cationic ring-opening polymerization (CROP). Using DLS and DOSY NMR experiments, their self-assemblies in water were compared with those of homologous photo-unreactive amphiphilic polyoxazolines (C_m–POx_n). In both cases, spherical nanoparticles with D_H-values around 10 nm were observed. The CoumC₁₁–POx_n nanoparticles were illuminated upon λ = 300 nm inducing the photo-dimerization of the coumarin units located in the inner compartment of the nanoparticles. Finally, the pros and the cons of the photo-dimerization of linear copolymers related to the photo-crosslinking of graft copolymers were discussed.