A series of polyurethaneurea (PUU) aqueous dispersions either with diethyltoluenediamine (DETDA) or ethylenediamine (EDA) as chain extender were prepared with polyester polyol, isophorone diisocyanate and dimethylol propionic acid (DMPA), and characterized. It was found that the physical properties of the PUU aqueous dispersions prepared with DETDA were similar to or better than those prepared with EDA. Compared with the EDAextended waterborne PUU films, the water resistance and the mechanical properties of the DETDA-extended waterborne PUU films were enhanced appreciably; these enhancements are attributed to the strong hydrogen bonding in urea carbonyl groups and the ordered structure of hard segments in the systems. The DETDA-extended PUU film with 40 wt.% of hard segment and 4.0 wt.% of DMPA unit showed the lowest water-absorbing amount (2.6 wt.%) over all PUU films studied. The hydrophobic surface of the DETDA-extended PUU film modified with a small amount of aminoethylaminopropyl polydimethylsiloxane (AEAPS) was observed and its hydrophobicity was enhanced by increasing the AEAPS content further.