INVESTIGADORES
PALMA Santiago Daniel
artículos
Título:
Coagels from Ascorbic Acid Derivatives
Autor/es:
SANTIAGO DANIEL PALMA; HILARIO MANZO, RUBEN; ALBERTO ALLEMANDI, DANIEL; LAURA FRATONI,; LO NOSTRO, PIERANDREA
Revista:
Langmuir
Referencias:
Año: 2002 vol. 18 p. 9219 - 9224
ISSN:
0743-7463
Resumen:
The 6-O-ascorbic acid alkanoates, ascorbyl-OCO(CH2)n-2CH3 (ASCn), behave as anionic surfactants in
water. At low water content (10% w/v) aqueous dispersions also form coagels at room temperature. These
hydrated crystalline phases transform to micellar solutions or gel phases, depending on the length of the
hydrophobic chain in the surfactant. The formation and properties of these phases were studied through
surface tension, differential scanning calorimetry (DSC), X-ray diffraction (XRD), conductivity, and
environmental scanning electron microscopy (ESEM). On heating, the shorter ascorbyl alkanoates (n eO-ascorbic acid alkanoates, ascorbyl-OCO(CH2)n-2CH3 (ASCn), behave as anionic surfactants in
water. At low water content (10% w/v) aqueous dispersions also form coagels at room temperature. These
hydrated crystalline phases transform to micellar solutions or gel phases, depending on the length of the
hydrophobic chain in the surfactant. The formation and properties of these phases were studied through
surface tension, differential scanning calorimetry (DSC), X-ray diffraction (XRD), conductivity, and
environmental scanning electron microscopy (ESEM). On heating, the shorter ascorbyl alkanoates (n en e
10) exhibit a coagel to micelle phase transition. By contrast the longer homologues (ng11) exhibit a coagel
to gel transition. The temperature, ¢H, and ¢S of the transitions depend on the length of the aliphatic
side chain. The different phase behavior is related to the interplay of the competing molecular interactions
that involve the hydrophobic chains of the amphiphiles, their headgroups, and the solvent.ng11) exhibit a coagel
to gel transition. The temperature, ¢H, and ¢S of the transitions depend on the length of the aliphatic
side chain. The different phase behavior is related to the interplay of the competing molecular interactions
that involve the hydrophobic chains of the amphiphiles, their headgroups, and the solvent.¢H, and ¢S of the transitions depend on the length of the aliphatic
side chain. The different phase behavior is related to the interplay of the competing molecular interactions
that involve the hydrophobic chains of the amphiphiles, their headgroups, and the solvent.