The buckling of a two-dimensional polymer network at the air-water int
erface has been evidenced by grazing incidence x-ray scattering. A com
prehensive description of the inhomogeneous octadecyltrichlorosilane p
olymerized film was obtained by atomic force microscopy and x-ray scat
tering measurements. The buckling occurs with a characteristic wavelen
gth congruent-to 10 mum.