Carbon nanotubes (CNTs) are promising nanofillers for light weight and high strength polymer composites due to their large aspect ratio, low density, and exceptional mechanical properties. Two major obstacles to the application of CNTs in polymer composites are their tendency to form bundles and aggregates, and low interfacial adhesion with polymer matrix. To solve these problems, both covalent and noncovalent strategies have been developed for functionalization of CNTs. This thesis centers on the design and synthesis of a series of polyimide dispersants to functionalize CNTs via either noncovalent approach or combination of covalent and noncovalent approaches, for fabrication of high-performance cyanate ester (CE) and polyimide (PI) composites. These dispersants effectively disperse CNTs via π−π interaction with nanotube sidewalls, and strongly interact with both CNTs and matrix to improve the nanotube/matrix interfacial adhesion, leading to significantly enhanced mechanical properties of composites.