Your browser doesn't support javascript.
loading
Polyion-surfactant ion complex salts formed by a random anionic copolyacid at different molar ratios of cationic surfactant: phase behavior with water and n-alcohols.
Percebom, Ana Maria; Piculell, Lennart; Loh, Watson.
Afiliação
  • Percebom AM; Institute of Chemistry, University of Campinas, Caixa Postal 6154, Campinas, SP 13083-970, Brazil.
J Phys Chem B ; 116(8): 2376-84, 2012 Mar 01.
Article em En | MEDLINE | ID: mdl-22288901
The presence of acid groups with different pK(a) values in the anionic copolymer poly(4-styrene sulfonic acid-co-maleic acid), P(SS-Ma), allowed the preparation of complex salts with a variable fraction of anionic groups neutralized by cationic surfactant in the copolymer via controlled titration with hexadecyltrimethylammonium hydroxide, C(16)TAOH. Two new complex salts were selected for detailed phase studies, C(16)TA(2)P(SS-Ma) and C(16)TA(3)P(SS-Ma), where both had 100% charged styrene sulfonate groups, but the fraction of charged carboxylate groups on the polyion was 50% or 100%, respectively. These complex salts thus contained both hydrophobic (styrene sulfonate) and hydrophilic (carboxylate) charged groups, and the ratio between the two could be altered by titration. These features were found to have consequences for the phase behavior in water and in ternary mixtures with water and n-alcohols for the two complex salts, which differed compared to complex salts containing homo- or copolyions with only carboxylate or styrene sulfonate charged groups. For both complex salts, binary mixtures with water produced, in the dilute region, two isotropic phases in equilibrium, the bottom (concentrated) one displaying increasing viscosity with increasing concentration. For the complex salt C(16)TA(2)P(SS-Ma), there was evidence of micellar growth to form anisometric aggregates at high concentrations. For the C(16)TA(3)P(SS-Ma) complex salt, this was not observed, and the isotropic phase was followed by a narrow region of cubic phase. In both cases, concentrations above ca. 60 wt % produced a hexagonal phase. For ternary mixtures with n-alcohols, the general trend was that a short-chain alcohol such as n-butanol acted as a cosolvent dissolving the aggregates, whereas with n-decanol, a cosurfactant effect was observed, inducing the formation of lamellar phases. Visual inspection (also between crossed polarizers), small angle X-ray scattering (SAXS) and diffusion nuclear magnetic resonance (NMR) were used in these studies.
Assuntos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Poliestirenos / Tensoativos / Água / Álcoois / Maleatos Tipo de estudo: Clinical_trials Idioma: En Revista: J Phys Chem B Assunto da revista: QUIMICA Ano de publicação: 2012 Tipo de documento: Article País de afiliação: Brasil País de publicação: Estados Unidos

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Poliestirenos / Tensoativos / Água / Álcoois / Maleatos Tipo de estudo: Clinical_trials Idioma: En Revista: J Phys Chem B Assunto da revista: QUIMICA Ano de publicação: 2012 Tipo de documento: Article País de afiliação: Brasil País de publicação: Estados Unidos