Polymer Cages as Universal Tools for the Precise Bottom-Up Synthesis of Metal Nanoparticles

A template synthesis allows the preparation of monodisperse nanoparticles with high reproducibility and independent from self-assembly requirements. Tailor-made polymer cages were used for the preparation of nanoparticles, which were made of cross-linked macromolecules with pendant thiol groups. Gold nanoparticles (AuNPs) were prepared in the polymer cages in situ, by using different amounts of cages versus gold. The polymer cages exhibited a certain capacity, below which the AuNPs could be grown with excellent control over the size and shape. Control experiments with a linear diblock copolymer showed a continuous increase in the AuNP size as the gold feed increased. This completely different behavior regarding the AuNP size evolution was attributed to the flexibility of the polymer chain depending on cross-linking. Moreover, the polymer cages were suitable for the encapsulation of AgNPs, PdNPs, and PtNPs by the in situ method.