Kinetically Controlled Star Copolymer Self-Assembly for Rapid Fabrication of Nanoparticles with High Encapsulation Capacity.

Rapid and scalable self-assembly of an amphiphilic 21-arm star copolymer, (polystyrene-block-polyethylene glycol) [(PS-b-PEG) ] in aqueous solution has been performed by reverse solvent exchange procedure. Transmission electron microscope (TEM) and nanoparticle tracking analysis (NTA) reveal the formation of nanoparticles with narrow size distribution. Further investigation indicates a kinetically controlled self-assembly mechanism of the copolymers, in which the star topology of the amphiphilic copolymer and deep quenching condition by reverse solvent exchange are key to accelerate intrachain contraction of the copolymer during phase separation. When interchain contraction dominant over interchain association, nanoparticles with low aggregation number could be formed. Thanks to the high hydrophobic contents of the (PS-b-PEG) polymers, the resulted nanoparticles could encapsulate a high capacity of hydrophobic cargo up to 19.84 %. The kinetically controlled star copolymer self-assembly process reported here provides a platform for the rapid and scalable fabrication of nanoparticle with high drug loading capacity (LC), which may find broad range of applications in, for example drug delivery, nanopesticide.