Influence of Au nanoparticle size and concentration on molecular transport and electrical conductivity in single polymer chains

This study investigates the effects of Au nanoparticle radius \({R}Au\) , nanoparticle concentration \({Φ}Au\) , and polymer chain length (N) on the permeability and electrical conductivity of polymer/Au nanocomposites. Since the solubility was assumed to be unity ( \(S=1\) ), the permeability (p) is equal to the effective diffusion coefficient \({D}eff, \) and both properties exhibit identical behavior. The results show that increasing Au concentration decreases \({D}eff\) (and hence p), while significantly enhancing electrical conductivity \(( \) ). The reduction in diffusion/permeability is more pronounced for larger nanoparticles, with \({D}eff\) decreasing by about 45% for \({R}Au=2.0 nm\) compared to only 13% for \({R}Au=0.3 nm\) as \(Φ_{{{Au}}}\) increase from 0.10 to 0.60. Polymer chain length has little influence on small nanoparticles but noticeably improves transport for larger nanoparticles. In contrast, conductivity increases nonlinearly with Au concentration and is consistently higher for smaller nanoparticles due to their larger surface area and improved conductivity network formation. The highest conductivity \(≈ 0.35\) S/m is obtained at \({Φ}Au\) = 0.60 and \({R}Au=0.3 nm\) . Overall, nanoparticle size is the dominant factor governing diffusion and permeability, whereas Au concentration primarily controls electrical conductivity.