Synthesis and Characterization of Surface Functional Polymer Nanoparticles by a Bottom-Up Approach from Tailor-Made Amphiphilic Block Copolymers

Core-crosslinked nanoparticles presenting secondary amine functional groups in the hydrophilic shell are synthesized by a bottom-up approach. The route utilizes polymerization of 2-oxazolines to prepare tailor-made block copolymers with a primary or secondary amine end group in the hydrophilic block and alkynyl moieties in the hydrophobic part of the polymer. Upon solubilization in the aqueous media, these block copolymers form micelles that are photocrosslinked by a radical polymerization process to afford two types of core-crosslinked nanoparticles, either with secondary amines, NP1, or primary amines, NP2, on the surface. The dimensions and stability of the core-crosslinked nanoparticles are characterized by dynamic light scattering and fluorescence spectroscopy. The availability and reactivity of the amine groups in the hydrophilic shell are demonstrated by reaction with different aromatic model compounds resulting in a degree of surface functionalization of 4-47% for NP1 nanoparticles with secondary amino groups and a 20-95% degree of surface functionalization for NP2 with primary amine groups, as determined by UV-vis spectroscopy.