The direct synthesis of interface-decorated reactive block copolymer nanoparticles via polymerisation-induced self-assembly†
Abstract
Self-assembly of amphiphilic block copolymers in water suffers from the undesired encapsulation of hydrophobic reactive motifs in a core-forming block, which deteriorates their performance as aqueous catalysts. This problem can be circumvented by polymerisation-induced self-assembly (PISA). Herein, we report a new strategy for one-pot synthesis of reactive block copolymer nanoparticles whose hydrophobic reactive motifs decorate the surrounding core–shell interfaces. We demonstrate fast RAFT aqueous dispersion polymerisation of a commercially available specialty monomer, diacetone acrylamide (DAAM), under visible light irradiation at 25 °C. PISA is induced by polymerisation via sequential dehydration, phase separation and reaction acceleration, thus achieving complete conversion in 30 min. The replacement of minimal DAAM by an NH3+-monomer induces slight hydration of the core-forming block, and thus a low polydispersity of the resulting statistic-block copolymer. Moreover, simultaneous in situ self-assembly and chain growth favour the adjustment of newly-added NH3+-units outward to core–shell interfaces while the major DAAM units collapse into hydrophobic PISA-cores. Both lead to timely and selective self-assembly into the new reactive nanoparticles whose NH3+-motifs decorate the surrounding core–shell interfaces. These nanoparticles are well-suited for fabrication of advanced nanoreactors whose hydrophobic dative metal centres decorate the surrounding interfaces via simultaneous imine conversion and Zn(II)-coordination. Such PISA-nanostructures endow hydrophobic metal centres with a huge and accessible specific surface area and are stabilized by water-soluble shells. Therefore, this strategy holds fascinating potential for the fabrication of metalloenzyme-inspired aqueous catalysts.