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Surface and aqueous properties of anionic gemini surfactants having dialkyl amide, carboxyl, and carboxylate groups
Author(s) -
Tsubone Kazuyuki,
Ogawa Tomoyasu,
Mimura Kunio
Publication year - 2003
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-003-0246-5
Subject(s) - chemistry , carboxylate , critical micelle concentration , protonation , pulmonary surfactant , amide , aqueous solution , monomer , micelle , thermodynamics of micellization , molecule , medicinal chemistry , stereochemistry , organic chemistry , ion , polymer , biochemistry
A systematic study of the equilibrium surface properties (in water and in the presence of 10 −2 M NaCl) of a novel series of anionic gemini surfactants, (CH 2 ) 2 [N(COC n H 2n+1 )CH(COOH)CH 2 COOH]·2NaOH (GA), where (n+1)=8, 10, 12, 14, and 16, was investigated. The responses of humans to closed patch tests with (CH 2 ) 2 [N(COC 11 H 23 )CH(COOH)−CH 2 COOH] 2 ·2NaOH (GA‐12) were also investigated. Premicellar self‐aggregation (both in water and 10 −2 M NaCl) occurred when the N ‐acyl group contained more than 14 carbon atoms, since the critical micelle concentration (CMC) values decreased and the pC 20 values increased as (n+1) increased for (n+1) ≤14; the CMC values increased and the p C 20 values decreased as (n+1) increased for (n+1)>14, both in water and in 10 −2 M NaCl. The absence of a break in the specific conductance‐surfactant molar concentration plots for the GA homologs indicates protonation of the carboxylate group and strong Na + release during micellization. This is a structural characteristic of the anionic geminis having N ‐dialkylamide and carboxylate groups in a molecule. The skin irritation potential of GA‐12 is lower than that of the corresponding “monomer”, C 11 H 23 CON(CH 3 )CH(COOH)CH 2 (COOH)·NaOH, and the analog, C 11 H 23 CON(CH 3 )CH 2 COONa·H 2 O.