Polymeric materials such as rubbers and plastics have been widely used in various applications due to their excellent characteristics, including lightweight, high toughness, ease of moldability, high electrical insulation, and more. However, in recent years, there has been a growing demand for engineering polymers to balance multiple, often conflicting functionalities. Highly functional nanofillers are expected to efficiently achieve new functionalities while maintaining the inherent properties of polymers, even with the addition of small amounts. In this Part V, we focus carbon nanotubes (CNTs) as nanofillers and present our research on the synthesis of noncovalent polymer dispersants for CNTs, which are effective in improving the dispersibility of CNTs in a polymer matrix. This is a major issue in the functionalization of polymer by adding CNTs. We also discuss a dispersion control method for CNTs in the polymer matrix, utilizing the phase-separated structure of polymer blends to localize CNTs in a specific phase, thereby efficiently enhancing the functionality of polymer systems.