title: Effect of Macrocycle Size on the Self-Assembly of Methylimidazolium Surfactant with Sulfonatocalix[n]arenes.
abstract: The effect of macrocycle size on the association of supramolecular amphiphiles composed of 4-sulfonatocalix[n]arene and 1-methyl-3-tetradecylimidazolium (C14mim+) was studied in aqueous solutions at pH 7. When the cavitand contained four sulfonatophenol units (SCX4), formation of spherical nanoparticles (NPs) was observed. By contrast, both supramolecular micelle (SM) and NP formation could be attained in the presence of NaCl when the larger, more flexible 4-sulfonatocalix[8]arene (SCX8) served as the host compound. The SCX8-promoted self-assembly into the SM was enthalpically more favorable than the NP production, but the molar heat capacity changes in the two processes barely differed. An addition of 50 mM NaCl significantly increased the enthalpy of C14mim+-SCX8 NP formation, thereby making the self-organization into the SM more favorable. The transformation of SM into NP at high temperatures was due to the substantial entropic contribution to the driving force behind the NP formation. The critical micelle concentration (cmc) and the local polarity in the headgroup domain were considerably lower for the SM compared with those of the conventional C14mim+Br-micelle.
authors.affiliation: Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences , P.O. Box 286, 1519 Budapest, Hungary.
authors.forename: József G
authors.initials: JG
authors.lastname: Harangozó
authors.affiliation: Université Paris Est, ICMPE (UMR7182), CNRS, UPEC , F 94320 Thiais, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Wintgens
authors.affiliation: Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences , P.O. Box 286, 1519 Budapest, Hungary.
authors.forename: Zsombor
authors.initials: Z
authors.lastname: Miskolczy
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Universités-UPMC Université Paris 06, UMR CNRS 7590, Muséum National d'Histoire Naturelle, Institut de Recherche pour le Développement UR 206 , 4 Place Jussieu, F-75005 Paris, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Guigner
authors.affiliation: Université Paris Est, ICMPE (UMR7182), CNRS, UPEC , F 94320 Thiais, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Amiel
authors.affiliation: Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences , P.O. Box 286, 1519 Budapest, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Biczók