A nanofiller masterbatch comprising a nanofiller and an ethylene/ester copolymer having copolymerized units of ethylene and a comonomer selected from monoesters of C4-C8 unsaturated acids having at least two carboxylic acid groups, diesters of C4-C8 unsaturated acids having at least two carboxylic acid groups, and mixtures of two or more thereof; and a nanocomposite comprising a polyolefin and the nanofiller masterbatch are disclosed. Processes for preparing the nanofiller masterbatch and the nanocomposite are also disclosed.