IMBIV   05474
INSTITUTO MULTIDISCIPLINARIO DE BIOLOGIA VEGETAL
Unidad Ejecutora - UE
artículos
Título:
New dendronized polymers from acrylate Behera amine and their ability to produce visco-elastic structured fluids when mixed with CTAT wormlike micelles
Autor/es:
JULIO CUGGINO; MARCELO CALDERÓN; CECILIA ALVAREZ I.; MIRIAM STRUMIA; KAROLAINE N. SILVA,; EVIS K. PENOTT-CHANG,; ALEJANDRO MÜLLER
Revista:
JOURNAL OF COLLOID AND INTERFACE SCIENCE
Editorial:
ACADEMIC PRESS INC ELSEVIER SCIENCE
Referencias:
Año: 2011 vol. 357 p. 147 - 156
ISSN:
0021-9797
Resumen:
Two new water soluble dendronized polymers (PLn) from acrylate Behera amine monomer
of different molecular weights were successfully synthesized. The polymers were
characterized by FTIR, NMR, GPC and DLS. Both GPC and DLS results indicated that
these PLn have a remarkable tendency to form aggregates in solution that lead to apparent
molecular weights that are much higher than their theoretical values, as well as large
diameters in solution. However, the addition of any PLn to water did not cause any
increase in viscosity up to concentrations of 1000 ppm.
The possible interactions of PLn with the cationic surfactant CTAT were explored by
solution rheometry. A synergistic viscosity enhancement was found by adding small
amounts of dendronized PLn polymers to a CTAT solution composed of entangled
wormlike micelles. The highest association tendency with CTAT was found for PL1 at the
maximum polymer concentration before phase separation (i.e., 100 ppm). The solution
viscosity at low shear rates could be increased by an order of magnitude upon addition of
100 ppm of PL1 to a 20 mM CTAT solution. For this mixture, the fluid obtained was
highly structured and exhibited only shear thinning behavior from the smallest shear rates
employed. These PL1/CTAT mixtures exhibited an improved elastic character (as
determined by dynamic rheometry) that translated in a much longer value of the cross-over
relaxation time and a pronounced thixotropic behavior which are indicative of a strong
intermolecular interaction.
In the case of the polymer with a higher theoretical molecular weight, PL2, its association
with CTAT leads to an extraordinary doubling of solution viscosity with just 0.25 ppm
polymer addition to a 20 mM CTAT solution. However, such synergistic viscosity
enhancement saturated at rather low concentrations (25 ppm) indicating an apparent lower
solubility as compared to PL1