TY - JOUR
T1 - Influence of Nanosegregation on the Surface Tension of Fluorinated Ionic Liquids
AU - Luís, Andreia
AU - Shimizu, Karina
AU - Araújo, Joao M M
AU - Carvalho, Pedro J.
AU - Lopes-Da-Silva, José A.
AU - Canongia Lopes, José N.
AU - Rebelo, Luís Paulo N
AU - Coutinho, Joao A. P.
AU - Freire, Mara G.
AU - Pereiro, Ana B.
PY - 2016/6/21
Y1 - 2016/6/21
N2 - We have investigated, both theoretically and experimentally, the balance between the presence of alkyl and perfluoroalkyl side chains on the surface organization and surface tension of fluorinated ionic liquids (FILs). A series of ionic liquids (ILs) composed of 1-alkyl-3-methylimidazolium cations ([CnC1im] with n = 2, 4, 6, 8, 10, or 12) combined with the perfluorobutanesulfonate anion was used. The surface tensions of the investigated liquid salts are considerably lower than those reported for non-fluorinated ionic liquids. The most surprising and striking feature is the identification, for the first time, of a minimum at n = 8 in the surface tension versus the length of the IL cation alkyl side chain. Supported by molecular dynamics (MD) simulations, it was found that this trend is a result of the competition between the two nonpolar domains (perfluorinated and aliphatic) pointing toward the gas-liquid interface, a phenomenon which occurs in ILs with perfluorinated anions. Furthermore, these ILs present the lowest surface entropy reported to date.
AB - We have investigated, both theoretically and experimentally, the balance between the presence of alkyl and perfluoroalkyl side chains on the surface organization and surface tension of fluorinated ionic liquids (FILs). A series of ionic liquids (ILs) composed of 1-alkyl-3-methylimidazolium cations ([CnC1im] with n = 2, 4, 6, 8, 10, or 12) combined with the perfluorobutanesulfonate anion was used. The surface tensions of the investigated liquid salts are considerably lower than those reported for non-fluorinated ionic liquids. The most surprising and striking feature is the identification, for the first time, of a minimum at n = 8 in the surface tension versus the length of the IL cation alkyl side chain. Supported by molecular dynamics (MD) simulations, it was found that this trend is a result of the competition between the two nonpolar domains (perfluorinated and aliphatic) pointing toward the gas-liquid interface, a phenomenon which occurs in ILs with perfluorinated anions. Furthermore, these ILs present the lowest surface entropy reported to date.
UR - http://www.scopus.com/inward/record.url?scp=84975797416&partnerID=8YFLogxK
U2 - 10.1021/acs.langmuir.6b00209
DO - 10.1021/acs.langmuir.6b00209
M3 - Article
AN - SCOPUS:84975797416
SN - 0743-7463
VL - 32
SP - 6130
EP - 6139
JO - Langmuir
JF - Langmuir
IS - 24
ER -