We have synthesized a difunctional model compound PAS-HFDE-PAS, obtained by condensation between a dianhydride (6-HFDA), hexafluoroisopropylidene-2,2＇-bis (phthalic acid anhydride) and two mole equivalents of para-aminostyrene (PAS) amines. It was then characterized using spectroscopic and thermal methods, including a kinetic study of monomer reactivity in the temperature range of 100-300 degrees C. The results enabled us to study and characterize two series of PAS-functionalized polyimides synthesized in the laboratory : phenylenediamine (PAS a polyimide) and cardo diamine (PAS polyimide) based. Thermomechanical data obtained with these polyimides showed the presence of two phase transitions, alpha and beta, associated with vitreous transition and with oscillation of phenylenebenzimide structures around the C(CF3)(2) flexible linkage of HFDA. A study of chemical structure (determined by H-1 and F-19 n.m.r.)/properties correlation study was carried out by determining the effect of molar mass and the type of diamine on the thermomechanical properties of telechelic polyimides before cross-linking.