Tuning nanoparticles' internal structure: fluorinated single-chain nanoparticles (SCNPs) generated by chain collapse of random copolymers

The generation of nanosized compartments in single chain nanoparticles (SCNPs) is a promising approach to generate individualized confinement-zones on a small scale for drug-encapsulation or catalysis. We here report the synthesis and characterization of compartmented, fluorinated SCNPs generated by single-chain collapse of amphiphilic copolymers. Polyethylene glycol (PEG) functionalized monomers were utilized as hydrophilic moieties, while hydrophobic residues were introduced using different mole fractions of either aliphatic or fluorinated monomers. Single chain collapse and subsequently crosslinking via copper-catalyzed azide-alkyne click reactions in selective and non-selective solvents yields internally structured SCNPs with hydrodynamic radii of 2.5-5.8 nm. All of the SCNPs exhibited water solubility, but displayed different compartmentations sized <1 nm, depending on the type of hydrophobicity and the monomer ratio. Investigations using continuous wave electron paramagnetic resonance and decay associated fluorescence spectroscopy, specifically targeting the hydrophobic cores of the SCNPs, revealed significant differences between the aliphatic and fluorinated cores of the SCNPs as probed by different specific molecular labels, finally allowing specific embedding of molecules into the specific compartments.