We have developed a method to synthesize well-defined spherical core-shell nanoparticles in a two-step one-pot process, which takes altogether less than 10 minutes. The first step consists in the ring-opening metathesis polymerization (ROMP) of a hydrophilic oligomeric norbornene derivative in polar organic aprotic solvent. This first step is completed within 5 minutes, after which a hydrophobic norbornene monomer is added together with additional alcoholic solvent. This second polymerization only 2 minutes and leads to the simultaneous self-assembly of the so-formed amphiphilic block copolymers, leading to a so-called PISA process (polymerization-induced self-assembly). Thanks to a well-controlled first polymerization step, a high blocking efficiency is obtained, with no apparent residual hydrophilic polymer.<br/>Nanoparticles with diameters ranging from 15 to 100 nm are easily obtained, with a narrow size distribution. Mixed morphologies are also observed in specific cases, with coexistence of spherical nanoparticles and short rods.<br/>The high functional-group tolerance of ROMP is here exploited to produce nitroxide-containing nanoparticles, without the need for post-polymerization modification. These particles are shown to efficiently catalyze the oxidation of various alcohols in aqueous mixtures, with a high recyclability potential through simple centrifugation processing. Furthermore, they exhibit excellent biocompatibility and antioxidant properties.

Nitroxide radical nanoparticles by ultrafast tandem ROMP/ROMPISA

2019 Spring National Meeting

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