The organic vapor absorption capacity of poly(methyl metacrylate) (PMMA), filled with oleic acid (OLEA) capped TiO2 nanocrystals (NCs) with curved shape, rod-like and spherical, is studied. The NC shape combined with the nature of the capping molecules can be used to enhance or reduce the PMMA ability to absorb different solvent molecules in a controlled way. Indeed, the arrangement of the ligands at the NC surface demonstrates an effective tool to control the extent of the interaction between the penetrating molecules and the embedded NCs from the outer to the inner specific chemical functionality of the coordinating ligand molecules.