Incorporating Spherical and Rod-Shaped Gold Nanoparticles into Polymeric Coacervates

Incorporating nanoparticles into soft materials offers a promising route to enhance the materials’ mechanical performance as well as to control availability of the nanoparticles. Among various additives, gold nanoparticles (AuNPs) are of particular interest due to their tunable morphology and surface chemistry and their catalytic and other chemical properties such as for enhanced chemical detection or sensing. In this study, we explore the integration of AuNPs into complex coacervates formed by poly(diallyldimethylammonium chloride) and poly(sodium acrylate). Our objectives were to understand the mechanism of nanoparticle incorporation, evaluate their dispersion, and assess their effect on the mechanical behavior of the coacervate matrix. Moreover, the availability of these incorporated nanoparticles was evaluated for their catalytic properties. Both spherical and rod-shaped AuNPs were synthesized and embedded within the coacervate phase. Small-angle X-ray scattering, coupled with a refined fitting model, was employed to analyze the nanoparticle distribution and internal structure of the polymer matrix. These results show that the coacervate enables a stable and homogeneous dispersion of the nanoparticles. Rheological measurements reveal that AuNPs enhance the shear modulus of the coacervate, with rod-shaped particles displaying greater effects, due to their greater aspect ratio. Importantly, the AuNPs retained their catalytic activity, while the coacervate matrix provided a facile means of catalyst recovery and reuse. These findings highlight coacervate-based nanocomposites as versatile, recyclable, and functional platforms for applications in catalysis and soft-material design.