Small-angle neutron scattering of mixed ionic perfluoropolyether micellar solutions (Articolo in rivista)

Type
Label
  • Small-angle neutron scattering of mixed ionic perfluoropolyether micellar solutions (Articolo in rivista) (literal)
Anno
  • 2007-01-01T00:00:00+01:00 (literal)
Alternative label
  • Gambi, CMC; Giordano, R; Chittofrati, A; Pieri, R; Laurati, M; Baglioni, P; Teixeira, J (2007)
    Small-angle neutron scattering of mixed ionic perfluoropolyether micellar solutions
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Gambi, CMC; Giordano, R; Chittofrati, A; Pieri, R; Laurati, M; Baglioni, P; Teixeira, J (literal)
Pagina inizio
  • 1348 (literal)
Pagina fine
  • 1353 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 111 (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Univ Florence, Dept Phys, I-50019 Florence, Italy; CNISM, I-50019 Florence, Italy; Univ Messina, Dept Phys, I-98010 Messina, Italy; CNISM, I-98010 Messina, Italy; Solvay Solexis Res & Technol, Phys Chem Interfaces, I-20021 Milan, Italy; Univ Dusseldorf, Phys Weichen Mat IPkM, D-40225 Dusseldorf, Germany; Univ Florida, Dept Chem, I-50019 Florence, Italy; CSGI, I-50019 Florence, Italy; CEA Saclay, CNRS, Leon Brillouin Lab, F-91191 Gif Sur Yvette, France; Univ Roma La Sapienza, CNR, INFM, CRS Soft Matter, I-00185 Rome, Italy (literal)
Titolo
  • Small-angle neutron scattering of mixed ionic perfluoropolyether micellar solutions (literal)
Abstract
  • Aqueous mixed micellar solutions of perfluoropolyether carboxylic salts with ammonium counterions have been studied by small-angle neutron scattering. Two surfactants differing in the tail length were mixed in proportions n2/n3 = 60/40 w/w, where n2 and n3 are the surfactants with two and three perfluoroisopropoxy units in the tail, respectively. The tails are chlorine-terminated. The mixed micellar solutions, in the concentration range 0.1-0.2 M and thermal interval 20-40 degrees C, show structural characteristics of the interfacial shell that are very similar to ammonium n2 micellar solutions previously investigated; thus, the physics of the interfacial region is dominated by the polar head and counterion. The shape and dimensions of the micelles are influenced by the presence of the n3 surfactant, whose chain length in the micelle is 2 A longer than that of the n2 surfactant. The n3 surfactant favors the ellipsoidal shape in the concentration range 0.1-0.2 M with a 1/2 ionization degree of n2 micelles. The very low surface charge of the mixed micelles is attributed to the increase in hydrophobic interactions between the surfactant tails, due to the longer n3 surfactant molecules in micelles. The closer packing of the tails decreases the micellar curvature and the repulsions between the polar heads, by surface charge neutralization of counterions migrating from the Gouy-Chapman diffuse layer, leading to micellar growth in ellipsoids with greater axial ratios. (literal)
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