ROLE OF HYDRATION AND CONFORMATIONAL-CHANGES IN ADSORPTION DYNAMICS OF ETHYL(HYDROXYETHYL)CELLULOSE AT THE AIR SOLUTION INTERFACE/

Previous studies have discussed the kinetics involved in the reduction in surface tension of ethyl(hydroxyethyl)cellulose (EHEC) at the air/ aqueous solution interface in terms of configuration changes involved in the transfer of individual polymer segments between soluted and ads orbed states. It was suggested that the process kinetics were governed by a substantially high activation barrier. In the present study, bas ed on molecular mechanic simulations, it is shown. that a nearly activ ation-free path between configurations exists for EHEC due to the extr eme flexibility of the polymer chain. Hence, the relatively slow kinet ics of the process should rather be attributed to a stepwise transform ation between conformations which is expressed as a sequence of elemen tary processes involving a considerable number of intermediate isomers . This occurs over an extended time period. Also, the configuration ch anges involved in the uncoiling of the polymer at the interface are re lated to the hydration effects.