In this section
@article{Tyagi:2021:10.1016/j.colsurfa.2021.126414,
author = {Tyagi, G and Seddon, D and Khodaparast, S and Sharratt, WN and Robles, ESJ and Cabral, JT},
doi = {10.1016/j.colsurfa.2021.126414},
journal = {Colloids and Surfaces A: Physicochemical and Engineering Aspects},
title = {Tensiometry and FTIR study of the synergy in mixed SDS:DDAO surfactant solutions at varying pH},
url = {http://dx.doi.org/10.1016/j.colsurfa.2021.126414},
volume = {618},
year = {2021}
}
TY - JOUR
AB - The interactions between a model anionic and amphoteric surfactant pair in aqueous solution are examined as a function of composition, at floating and fixed pH, employing a combination of tensiometry, regular solution theory analysis, and FTIR spectroscopy. An extensive series of pure and mixed ratios of sodium dodecyl sulfate (SDS) and N,N-dimethyldodecylamine N-oxide (DDAO), ranging from 0.0016 to 100 mM, yielding 77 data points below and above the critical micelle concentrations (CMC), is investigated. Compared to either pure surfactant solutions, the CMC of mixed SDS:DDAO solutions is found to decrease by up to 20-fold, and the surface tension (γ) at CMC down to 23 mN/m. At all concentrations, the most prominent effects are observed at equimolar SDS:DDAO ratios. Further, the pH of mixed micellar solutions is found to increase with respect to the pure surfactant solutions (from 7 up to 9.5), which is attributed to the enhanced protonation of DDAO in the presence of SDS, and supported by FTIR frequency shifts of isolated OH stretching vibrations. Vibrational responses from CH2 stretching of the methylene tails, and the SO stretching modes for the sulfate headgroups indicate strong lateral interaction and enhanced packing between SDS and DDAO. From regular solution theory analysis of tensiometry data, the molecular interaction parameters are found to have a larger magnitude (i.e., more negative) at the interface as compared to within micelles. At fixed solution pH, a decrease from pH 9.5 to 7.5 results in minimal changes in both interfacial and micellar parameters, indicating the intrinsic origin of these pairwise interactions. Overall, our findings demonstrate a pronounced synergistic interaction between SDS and DDAO, arising from diminished electrostatic and steric repulsions in, respectively, SDS and DDAO, accompanied by enhanced lateral surfactant packing.
AU - Tyagi,G
AU - Seddon,D
AU - Khodaparast,S
AU - Sharratt,WN
AU - Robles,ESJ
AU - Cabral,JT
DO - 10.1016/j.colsurfa.2021.126414
PY - 2021///
SN - 0927-7757
TI - Tensiometry and FTIR study of the synergy in mixed SDS:DDAO surfactant solutions at varying pH
T2 - Colloids and Surfaces A: Physicochemical and Engineering Aspects
UR - http://dx.doi.org/10.1016/j.colsurfa.2021.126414
UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000642467400004&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR - https://www.sciencedirect.com/science/article/pii/S0927775721002831?via%3Dihub
UR - http://hdl.handle.net/10044/1/97199
VL - 618
ER -