A combined theory-experiment analysis of adsorbing polymer mediated structural icorganization of silica nanoparticles in equilibiated and miscible poly(ethylene oxide) (PEO) and polytetrahydifuran (PTHF) nanocomposites is presented Quantitative comparison of microscopic liquid state theory calculations with small-angle X-ray scattering experiments demonstrate the theoretical approach property accounts For the effects of adsorbed polymer layer on nanoparticle concentration fluctuation over all length scales For I wide range Or volume fractions and Interracial cohesion strengths The mixture total packing fraction is increased as particles are added to the polymer melt in order to account for equation-or-suite effects which are important at very high filler loadings A distinctive microphase separation like peak in the collective polymer structure fiactor is predicted. Nanopaiticle potential of mean force Calculations suggest a criterion for the onset of depiction or bridging induced kinetic gelation which is consistent with the observation of complete miscibility for the PEO system but nonequilibrium behavior in the PTHF nanocomposite