Polymer/AgPt bimetallic nanoparticle synergy: optimizing plasmonic durability through controlled synthesis and matrix integration.

An innovative approach combining UV-induced polymerization and ultra-high vacuum (UHV) atomic vapor deposition was developed to synthesize and disperse 2-3 nm AgPt bimetallic nanoparticles (BNPs) within a non-porous poly (dipropylene glycol diacrylate) (PDGDA) matrix, surpassing conventional porous polymer strategies. This method offers unprecedented control over the structural properties of BNPs and in general nanoalloys, with the polymer matrix playing a critical role in regulating nanoparticle formation, spatial arrangement, and size uniformity. The PDGDA matrix enhances nanoparticle stability through steric stabilization and controlled diffusion, effectively maintaining small nanoparticle sizes (∼2.4-2.8 nm) and low dispersity (σ _D/D = 0.16) during extended high-temperature annealing. Confinement of nanoparticles (NPs) was significantly accelerated by successive thermal annealing to 320 °C, which increased polymer chain mobility and reduced viscosity, enabling rapid diffusion while preserving the structural integrity of the polymer matrix. This process dramatically reduced the embedding time from 12 days at room temperature to near-instantaneous incorporation upon heating. Successful confinement is attributed to key thermodynamic factors that promote interfacial interactions and particle mobility within the polymer network. Experimental results reveal distinctive UV plasmonic properties of the embedded AgPt BNPs with long-term stability. The produced AgPt BNPs exhibit significantly stronger localized surface plasmon resonances (LSPRs) than pure platinum nanoparticles, attributed to synergistic effects between the two metals. Factors contributing to this enhancement include silver's high electrical conductivity and relatively low optical losses, electromagnetic coupling, and localized electric field enhancement, highlighting the potential of these BNPs for advanced plasmonics. This research addresses the growing demand for surface-enhanced Raman scattering (SERS) detection of UV-absorbing biospecies and the development of more efficient broad-spectrum solar cells.