fabric coatings while water vapors can. On the other hand, when
hydrophilic nonporous films are employed, water vapors can penetrate
the fabric coatings through the hydrophilic segments by a
sorption–diffusion–desorption mechanism. Since it may be diffi-
cult to keep water off from the microporous films over a long
time period, various types of hydrophilic films have been employed
recently for waterproof breathable products. Furthermore, complicated
processes are required to produce microporous film-coated
fabrics. Other advantages of hydrophilic PU coatings over microporous
PU coatings are better adhesion on textile substrates and
lower cost [9]. Presently, in breathable waterproof applications,
solvent-borne PUs have been displaced by waterborne PUs due to
environmental requirements. In addition, waterborne PUs exhibit
excellent adhesion to textiles [9–12]. Another disadvantage of
solvent-borne PUs is that the excess solvent can damage their films
on textiles [13].