Hybrid organic/inorganic nanocomposites based on polyhedral oligomeric silsesquioxane (POSS) nanostructured chemicals and nylon 6 were prepared via melt mixing. Two structurally and chemically different POSS molecules, a closed cage, nonpolar octaisobutyl POSS (Oib-POSS) and an open cage, polar trisilanolphenyl POSS (Tsp-POSS) with differing predicted solubility parameters were evaluated in the nylon matrix. Surface analysis, including quasi-static and dynamic nanoindentation and nanotribological techniques, revealed exceptional improvements in modulus and hardness along with significant reductions in friction. Additionally, surface wetting characteristics of the nylon were reversed, with POSS incorporation yielding low surface energy, highly hydrophobic surfaces. AFM, TEM/EDAX, spectroscopic techniques and thermomechanical analysis were used to evaluate nanoscale dispersion and bulk properties of the composites. Both POSS molecules exhibit preferential surface segregation behavior in the nylon matrix. Tsp-POSS, with its higher predicted solubility in nylon, exhibited enhanced dispersion and tribomechanical properties at both nano and bulk scale. 0 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1088-1102,2009