The equilibrium properties of the monolayers of three diblock and two triblock copolymers composed of polystyrene (PS) and poly(ethylene oxide) (PEO), at the air-water interface, have been obtained between 5 and 35 degreesC. The results have been discussed in terms of the dilute, self-similar layer (SSL) and quasi-brush regimes predicted by scaling and self-consistent-field theories. The SSL to quasi-brush transition was found to be continuous. Below the transition, a master curve was obtained for the isotherms of the diblock copolymers when the area axis was normalized by the number of ethylene oxide groups in the chain. For the two triblock samples, it was not possible to build a master curve. The two copolymers with the largest PS blocks show isotherms that collapse before the brush state was reached. The dynamics of the monolayers was studied using a combination of experimental techniques that has allowed us to obtain data over a broad frequency range: 0.01 Hz to 100 kHz. In all the cases, the dynamic elasticity epsilon was larger than the equilibrium compression modulus, which points out the viscoelastic character of the monolayers. As the SSL structure develops, the number of tails and loops protruding into the subphase increases. These tails and loops are very effective in dissipating the stress, thus leading to a decrease of E until the end of the SSL-quasi-brush transition where, for some block copolymers, the interaction between the stretched PEO chains in the subphase contributes to a further increase of c. Negative apparent dilational viscosities appear for the triblock copolymer with a PS block larger than the PEO ones. The data have been analyzed in terms of two recently proposed dispersion equations. Although one of them is able to reproduce the SQELS spectra without negative apparent dilational viscosities, the molecular meaning of one of the parameters used is not yet clear.