Two new aromatic diamines, 3-tert-butyl-4,4'-diaminodiphenyl ether (1) and 3,3'-di(tert-butyl)-4,4'-diaminodiphenyl ether (2), were synthesized by the Ullmann coupling reaction. Both of them were used to prepare polyimides via one-step polycondensation with some commercial aromatic dianhydrides. The effect of tert-butyl groups on the physicalechemical properties of the resulting polyimides was investigated by NMR, GPC, DSC, TGA, XRD, FTIR and UVeVis spectra etc. They are soluble in common organic solvents, such as NMP, DMAc, THF and CH3Cl etc. The number-average molecular weights are in the range from 16,400 to 73,600 with the PDI from 2.23 to 2.85. The transparent polyimide films in the visible region (400-780 nm) can be obtained by the solution-casting. XRD measurement results demonstrate that these polyimide films are amorphous polymers. Particularly, the polyimide films from diamines (1) and (2) with BPADA display high flexibility and their elongation at break was above 60%. In summary, the polyimides with double-substituted tert-butyl groups exhibit much better performance than that from with single-substituted tert-butyl group. (C) 2015 Elsevier Ltd. All rights reserved.