Ultrasonic Control\nof Polymer-Capped Plasmonic Molecules

Plasmonic molecules (PMs) composed of polymer-capped\nnanoparticles\nrepresent an emerging material class with precise optical functionalities.\nHowever, achieving controlled structural changes in metallic nanoparticle\naggregation at the nanoscale, similar to the modification of atomic\nstructures, remains challenging. This study demonstrates the 2D/3D\nisomerization of such plasmonic molecules induced by a controlled\nultrasound process. We used two types of gold nanoparticles, each\nfunctionalized with hydrogen bonding (HB) donor or acceptor polymers,\nto self-assemble into different AB<sub><i>N</i></sub>-type\ncomplexes via interparticle polymer bundles acting as molecular bonds.\nPost-ultrasonication treatment significantly shortens these bonds\nfrom approximately 14 to 2 nm by enhancing HB cross-linking within\nthe bundles. This drastic change in the bond length increases the\nstiffness of the resulting clusters, facilitating the transition from\n2D to 3D configurations in 100% yield during drop-casting onto substrates.\nOur results advance the precise control of PMs’ nanoarchitectures\nand provide insights for their broad applications in sensing, optoelectronics,\nand metamaterials.