PUI block copolymers with three diferent soft segments were synthesized and characterized．FTIR spectroscopy studies confirmed the characteristic absorption of polyurethane-imide main chain structure of all PUI samples．DSC analysis revealed that the values of the glass transition temperature of hard segments rich phase (Tgh) were increased with all increase of soft segments length for the same kind soft segment．DSC results additionally support that with an increase of soft segment length

the soft and hard segments phase compatibility was decreased and the soft-hard block phase was more separable．TGA revealed that the thermal stability of different soft segment PUI was in the order of PEPA-PUI＞PEG-PUI＞PPO-PUI

and dynamic mechanical thermal analysis (DMTA) of PUI samples also showed that the storage energy modulus platform dropping is not remarkable from 50～200℃

this result proved that thermo-plastic PUI elastomer samples may have good thermal mechanical properties

which was found to be improved by increasing the hard segments content of PUI systems．