Preparation and properties of waterborne polyurethaneurea consisting of α, ω-dihydroxypoly [(3,3,3-trifluoropropyl) methylsiloxane] units

A series of polyurethaneurea (PUU) aqueous dispersions modified with α, ω-dihydroxypoly [(3, 3, 3-trifluoropropyl) methylsiloxane] (PTFPMS) were prepared. These anionic-type aqueous dispersions were stable at ambient temperature and showed excellent high-temperature and freeze/thaw stability. For these aqueous dispersions, the surface tension decreased as the PTFPMS content increased, however the particle size increased at first then decreased. The PUU film modified with small amount of PTFPMS (5wt%) exhibited excellent water proof performance. The amount of water absorption was as low as 4.9wt%, and the contact angle of water on the film surface was as high as 90°. The experimental results showed that there was high degree of hydrogen bonding for urea carbonyl groups in the PTFPMS-modified system, and the increased microphase separation degree between the hard and soft segments resulted in significant enhancement of the mechanical properties of the modified PUU films.