Microcalorimetric Study of Some Short-Chain Nonionic Surfactants

Mixed Micellar Aggregates of Nonionic and Anionic Surfactants with Short Hydrophobic Tails: A Microcalorimetric Study

“…They can be attributed to different hydration structures of C 6 E 5 present in solution. Similar results were found for the C 8 E 5 solutions (8). It is interesting to note that surfactants with short hydrophobic tails, such as C 6 E 5, that usually form small aggregates with loose structure (14,15), also give rise to phase transitions in the concentrated composition range.…”

“…For the nonionic surfactant C 6 E 5 , a linear trend of the apparent molar relative enthalpy, ( ) E , with molality, m E , in the premicellar composition range (m E < 0.104 mol kg −1 ) was found by some of us in the past (8). The data fit the following equation:…”

“…We focused our attention on short tail surfactants having cmc values at concentrations high enough to allow experimental investigation also in the premicellar composition range. At the same time C 6 E 5 and C 6 SNa show all the characteristics of a typical surfactant (7,8). The investigations on the water-C 6 E 5 -C 6 SNa system showed the formation of mixed micellar aggregates, to which both surfactants participate.…”

“…The apparent molar relative enthalpies, ( ) S , computed as discussed in a previous paper (8), are shown in Fig. 1.…”

“…The cmc and the molar enthalpy of micellization of C 6 SNa, h S , shown in Table 1, have been evaluated as reported previously (8).…”