TY - JOUR A1 - Avranas, Antonis A1 - Komnianou, A. A1 - Retter, Utz T1 - On the adsorption and condensed filmformation of dodecyl-, tetradecyl-, hexadecyl-, and octadecyltrimethylammonium bromides at the mercury/electrolyte interface N2 - The adsorption and condensed film formation of dodecyl (DTAB)-, tetradecyl (TTAB)-, hexadecyl (CTAB)-, and octadecyl (OTAB)-trimethylammonium bromides on the hanging mercury electrode is studied in KBr as supporting electrolyte, at various temperatures from 5 to 45 °C. A condensed film is formed at negative potentials and at room temperature only in the presence of CTAB. The decrease of the temperature favors the formation of the condensed film. A transition temperature is observed for the film formation. Capacity–time curves at the potentials where the film is formed show a nucleation and growth mechanism, with induction time depending not only on the final potential but also on the initial potential range, although it is in the desorption region. In this temperature range no film is observed for DTAB and TTAB. However, the film is observed for OTAB, but only at higher temperatures, and is more easily formed with increasing temperature. The film is formed in a certain potential region and the nucleation rate increases while moving toward more negative potentials. Hysteresis phenomena are observed during changes of scan direction. The capacity vs time curves for OTAB, where condensed film is formed, are treated using an Avrami plot formulation and have been explained as progressive one-dimensional nucleation with a decrease of the nucleation rate during the overall film formation. The results show a marked effect of the chain length of the alkyl chain on the film formation. KW - Dodecyltrimethylammonium bromide KW - Tetradecyltrimethylammonium bromide KW - Cetyltrimethylammonium bromide KW - Octadecyltrimethylammonium bromide KW - Differential capacity KW - Condensed film KW - Nucleation PY - 2003 DO - https://doi.org/10.1016/S0021-9797(03)00534-4 SN - 0021-9797 SN - 1095-7103 VL - 264 IS - 2 SP - 407 EP - 413 PB - Elsevier CY - Orlando, Fla. AN - OPUS4-2715 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Retter, Utz A1 - Avranas, Antonis T1 - On anion-induced formation of hemicylindrical and hemispherical surface micelles of amphiphiles at the metal/electrolyte interface PY - 2001 SN - 0743-7463 SN - 1520-5827 PB - American Chemical Society CY - Washington, DC AN - OPUS4-1069 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Avranas, Antonis A1 - Retter, Utz A1 - Malasidou, Efi T1 - The Adsorption and Condensed Film Formation of Cetyltrimethylammonium Bromide at the Mercury/Electrolyte Interface N2 - The adsorption of cetyltrimethyammonium bromide (CTAB) on a hanging mercury electrode is studied in various electrolyte systems and temperatures. A condensed film is formed at negative potentials and at room temperature only in the presence of KBr. The decrease of the temperature favors the formation of the condensed film. Hysterisis phenomena are observed during the potential scans at both directions. Capacity time curves at the potentials where the film is formed show a nucleation and growth mechanism, with induction time depending on potential, which has been investigated using Avrami formulation and has been explained as a progressive one-dimensional nucleation with constant growth rate. The nucleation rate increases while moving toward more negative potentials. A linear decrease of the capacitance with time was observed in some cases independent of the measuring potential in a relative large potential range. The different types of micelles can affect the adsorption of CTAB on mercury. An unusual capacitance transient observed at a very narrow negative potential range is attributed to the formation of hemicylinders. The condensed film in the presence of the other electrolytes is observed only at high concentrations (1 M) and very low temperatures (5°C). KW - Cetyltrimethylammonium bromide KW - Differential capacity KW - Condensed film KW - Hysterisis phenomena PY - 2002 DO - https://doi.org/10.1006/jcis.2001.8180 SN - 0021-9797 SN - 1095-7103 VL - 248 SP - 347 EP - 354 PB - Elsevier CY - Orlando, Fla. AN - OPUS4-1642 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Retter, Utz A1 - Tchachnikova, M. A1 - Avranas, Antonis T1 - On Packing Constraints in the Formation of Surface Micelles of Amphiphiles at the Metal/Electrolyte Interface - The Necessity of Introducing a Generalized Packing Parameter N2 - The long-term capacity–time dependence of 1-decanol was measured at the mercury/electrolyte interface for the electrolytes KCl, NaCl, LiBr, and K2SO4, each of concentration 0.1 M, in the temperature range 20 to 50°C and at 35°C for electrolyte concentrations of NaCl in the region 0.05 to 0.4 M. All capacity–time dependences exhibited a slow increase of the capacity after a sudden decrease in the short-term range. The corresponding long-term time dependence of the degree of coverage can be theoretically well described with a first-order surface reaction. The ratios of final equilibrium capacity to minimal capacity can be explained with the formation of hemispherical or bilayer surface micelles from an initial monolayer of perpendicularly adsorbed molecules. A generalized packing parameter that involves the increase or decrease of the head groups' distance due to electrolyte ions or other surfactants was introduced. In the case of bilayers of parallel adsorbed molecules, obviously a new type of transition, which will be discussed in detail, occurs. KW - Surface micelles KW - Surface Packing parameter KW - 1-decanol KW - Differential capacity KW - Interface metal/electrolyte PY - 2002 DO - https://doi.org/10.1006/jcis.2002.8390 SN - 0021-9797 SN - 1095-7103 VL - 251 SP - 94 EP - 100 PB - Elsevier CY - Orlando, Fla. AN - OPUS4-1643 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -