IMBIV   05474
INSTITUTO MULTIDISCIPLINARIO DE BIOLOGIA VEGETAL
Unidad Ejecutora - UE
artículos
Título:
Synthesis of amphiphilic dendrons and their interactions in aqueous colutions with cetyltrimethylammonium ptoluensulfonate (CTAT)
Autor/es:
MARCELO CALDERÓN; MANUEL VELASCO; MIRIAM STRUMIA; ARNALDO LORENZO; ALEJANDRO MÜLLER; MARIO ROJAS; EDUARDO SÁEZ
Revista:
JOURNAL OF COLLOID AND INTERFACE SCIENCE
Editorial:
ACADEMIC PRESS INC ELSEVIER SCIENCE
Referencias:
Año: 2009 p. 462 - 469
ISSN:
0021-9797
Resumen:
In this work, we report synthesis and rheology of an interesting structured fluid based on the self-assembly
of amphiphilic dendrons and wormlike micelles. Two amphiphilic dendrons were synthesized by the
combination of aliphatic chains and polar dendritic heads. They showed different degrees of hydrophobicity
and formed micelles in aqueous solution at critical micelle concentrations (CMC) of 25 and
125 ppm. The dendrons were soluble in water up to a concentration of approximately 1200 ppm, and
produced no measurable increase in the viscosity of the solvent. The rheology of solutions of mixtures
of each dendron with cetyltrimethylammonium p-toluenesulfonate (CTAT, a cationic surfactant) was
characterized in simple shear flow. In the concentration range in which CTAT forms semidilute solutions
of wormlike micelles, dendron addition produced a substantial synergy in zero-shear rate viscosity. Parallel-
plate oscillatory shear measurements demonstrated that the CTAT/dendron mixtures are significantly
more elastic than CTAT solutions. The viscosity synergy occurs at dendron concentrations lower
than their CMC, and it is stronger for the more hydrophobic dendron. This suggests that the interactions
between dendrons and wormlike micelles are basically hydrophobic, which implies attachment of dendron
micelles to wormlike CTAT micelles in a manner similar to micellization of surfactants on
polyelectrolytes.p-toluenesulfonate (CTAT, a cationic surfactant) was
characterized in simple shear flow. In the concentration range in which CTAT forms semidilute solutions
of wormlike micelles, dendron addition produced a substantial synergy in zero-shear rate viscosity. Parallel-
plate oscillatory shear measurements demonstrated that the CTAT/dendron mixtures are significantly
more elastic than CTAT solutions. The viscosity synergy occurs at dendron concentrations lower
than their CMC, and it is stronger for the more hydrophobic dendron. This suggests that the interactions
between dendrons and wormlike micelles are basically hydrophobic, which implies attachment of dendron
micelles to wormlike CTAT micelles in a manner similar to micellization of surfactants on
polyelectrolytes.