F. Joabsson et al., Interfacial interaction between cellulose derivatives and surfactants at solid surfaces. An ellipsometry study, LANGMUIR, 17(5), 2001, pp. 1499-1505
The effect of surfactants on the adsorption properties of ethyl(hydroxyethy
l)cellulose (EHEC) and its hydrophobically modified analogue (HM-EHEC) at t
he solid-liquid interface has been studied by ellipsometry. The adsorption
characteristics of EHEC and HM EHEC without the presence of surfactants are
also presented. The polar silica surface and a hydrophobized silica surfac
e were used as substrates. On the polar silica surface, a small addition of
the anionic surfactant sodium dodecyl sulfate (SDS) caused a 3- to 5-fold
expansion of the preadsorbed EHEC or HM-EHEC layers, while the adsorbed amo
unt was less influenced. On the hydrophobized silica surface, SDS could rep
lace EHEC (>10 mM SDS), while some adsorbed HM-EHEC still could be detected
well above the critical micelle concentration of SDS in the bulk (14 mM).
The nonionic surfactant octa(ethylene oxide) dodecyl ether (C12E8) did not
affect the adsorbed layer structure on silica, and the cationic surfactant
cetyltriammonium chloride (CTAC) on hydrophobized silica showed similar eff
ects as SDS but with a smaller magnitude. It is proposed that the adsorbed
layer structure mainly is governed by polymer-surfactant interfacial intera
ctions.