Perfluorophenyl Azides: Photo, Staudinger, and Multicomponent Postpolymerization Reactions on Homopolymers and PISA-Made Nanoparticles

A novel monomer, 4-azido-2,3,5,6-tetrafluorobenzyl methacrylate (ABMA), enabled the selective and efficient postpolymerization modification of reversible addition–fragmentation chain transfer(RAFT)-made homopolymers and diblock copolymer nanoparticles prepared through polymerization-induced self-assembly (PISA). Poly(ABMA) homopolymers were modified postpolymerization in (near-)quantitative conversions with phosphines to give stable iminophosphoranes and in a multicomponent reaction with phenylacetaldehyde and morpholine, piperidine, or the cross-linker N,N′-dimethylethylene diamine to give the corresponding amidine derivatives in one step. Product polymers were characterized by nuclear magnetic resonance and Fourier-transform infrared spectroscopy, size-exclusion chromatography, and differential scanning calorimetry. Unlike its monomer, poly(ABMA) was insoluble in ethanol and enabled the preparation of well-defined spherical, worm-shaped, and vesicular nanoparticles with azide-functional cores through RAFT dispersion polymerization with concurrent PISA. The worm-shaped particles formed physical gels that underwent a thermally reversible degelation. Multicomponent modification of spherical nanoparticles with phenyl acetaldehyde and morpholine or piperidine led to (near-)quantitative core modification and for morpholine, a significant increase in its sphere diameter. UV irradiation of nanoparticles led to cross-linking through the formation of reactive nitrene intermediates, which prevented the disassembly of nanoparticles in nonselective solvents, representing a simple and reagent-free cross-linking strategy and expanding the scope of azide-based polymer chemistry.