Interactions between gemini surfactants and polymers: Thermodynamic studies (Articolo in rivista)

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Label
  • Interactions between gemini surfactants and polymers: Thermodynamic studies (Articolo in rivista) (literal)
Anno
  • 2007-01-01T00:00:00+01:00 (literal)
Alternative label
  • Muzzalupo, R; Infante, MR; Perez, L; Pinazo, A; Marques, EF; Antonelli, ML; Strinati, C; La Mesa, C (2007)
    Interactions between gemini surfactants and polymers: Thermodynamic studies
    in Langmuir
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Muzzalupo, R; Infante, MR; Perez, L; Pinazo, A; Marques, EF; Antonelli, ML; Strinati, C; La Mesa, C (literal)
Pagina inizio
  • 5963 (literal)
Pagina fine
  • 5970 (literal)
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  • 23 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Univ Calabria, Dipartimento Sci Farmaceut, I-87030 Arcavacata Di Rende, CS, Italy; Consejo Super Invest Cientificas, Inst Invest Quim & Ambientales, Dept Tecnol & Tensioactivos, Barcelona 08034, Spain; Univ Porto, Fac Ciencias, Dept Quim, Ctr Invest & Quim, Oporto, Portugal; Univ Roma La Sapienza, Dipartimento Chim, I-00185 Rome, Italy; Univ Roma La Sapienza, SOFT INFM CNR Res Ctr, I-00185 Rome, Italy (literal)
Titolo
  • Interactions between gemini surfactants and polymers: Thermodynamic studies (literal)
Abstract
  • Aqueous mixtures containing a homopolymer, poly(vinylpyrrolidone) (PVP), or a hydrophobically modified graft copolymer, HM-pullulan, (PULAU(9), where 9 stands for the nominal substitution degree), and different Gemini surfactants have been investigated at 25.0 degrees C. A wide variety of experimental conditions were addressed by changing the amount of polymer and of surfactant. The Gemini surfactants were synthesized, purified, and characterized by routine methods. They differ from each other in polar head groups (two sulfonate-, two quaternary ammonium-, or two arginine-based groups), in alkyl chain length (11 or 12 carbon atoms), and in the distance between the polar head groups. The spacers consist of 2, 3, and 6 methylene units or 3 oxyethylene units. Surface activity and solution calorimetry measurements yield some physicochemical features inherent to micelle formation and polymer-surfactant interactions. The data are supported by ionic conductivity, detecting the critical thresholds and quantifying the modifications in binding associated with critical association (CAC) and micelle formation (CMC*). The Gibbs energy of transfer from the micelles to a polymer-binding site, Delta G(trans), was evaluated from the CAC/CMC* ratios versus the amount of added polymer. A similar procedure determined the enthalpy of transfer, Delta H-trans. Delta G(trans) decreases with added polymer, whereas Delta H-trans becomes more negative on increasing the amount of polymer in the medium. According to the selected data presented here, cationic Geminis do not interact with PVP, while significant interactions have been observed in other surfactants. In mixtures with PULAU(9), the interaction is significant for all Geminis. This effect is due to interactions between the surfactants and the hydrophobic alkyl groups on the main polymer chain. The pendent groups facing away from the polysaccharide chain act as binding sites for aggregates onto such polymers. (literal)
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