The main objectives of this work were to construct and characterize polypropylene and adamantane (PP/ADM) nanocomposites experimentally and to identify their mechanical properties using molecular dynamics (MD) simulation. Samples with different contents of ADMs (0.5, 1, 2 and 4 weight percent (wt%)) were prepared using melt mixing method. It was observed that ADM nanofillers had significant effects on mechanical properties (Young’s modulus) of PP nanocomposites. Furthermore an appropriate simulation model was developed to find mechanisms of dispersion and aggregation of the ADMs and to predict bulk properties of the nanocomposite. While former researches claimed that homogeneous filler dispersion exists only at the intermediate level of interfacial interaction between polymer and nanoparticle, according to results of current study entropy has substantial influence on dispersion process. In other words, entropy which controls the interfacial parameters such as how ADMs attach to the polymer chains (either by chain end or middle of the backbone), is a determining agent in dispersion and aggregation mechanism. Consequently chains entropy plays a significant role in enhancement of the nanocomposites Young’s modulus. The trend of modulus alterations demonstrated that the entrance of ADMs at the chains contact point reinforced the polymer matrix and hence increased the modulus intensively. On the other hand, relative dispersion of ADMs and their small aggregates enhanced the modulus. However, ADMs aggregation caused by attaching to the joined ends, made a dramatic decline in Young’s modulus.