Silylate-terminated polyurethanes with built-in hydrophilic sites were synthesized.When the polymer is dispersed in water

the silane alkoxy end-groups of the polymer undergo hydrolysis

followed by condensation to form a stable cross-linked aqueous dispersion.TEM studies indicated that with more incorporation of hydrophilic sites

the particle size of the dispersion decreased.It was also found that the film property depended on the particle size when the crosslinking density in particels was much higher. The average molecular weight of the elastically effective network chain Mc measured by swelling experiments shows fairly good agreement with the theoretical value of Mc.It was also found that the cross-linking density of the casting film may increase during the film formation and drying process.