Selective incorporation of one of the isomers of a photoswitchable molecule in wormlike micelles
Por:
Rincon-Londono, Natalia, Garza, Cristina, Esturau-Escofet, Nuria, Kozina, Anna, Castillo, Rolando
Publicada:
5 feb 2021
Resumen:
Understanding the physical and chemical mechanisms underlying the
interactions between giant micelles and photoswitchable molecules is
essential because it is not evident why some photoswitchable
chromophores with apparently good potential to modify micellar systems'
macroscopic properties have a poor performance on UV-irradiation. We
report a mechanism that describes the trans-isomer's expulsion embedded
in the wormlike micelles when it is transformed into the cis-isomer on
UV-irradiation. Consequently, a small change in the rheological
properties of the micellar solution is observed on UV-irradiation. As a
model system, 4-(phenylazo) benzoate ion as the photoresponsive
chromophore and giant cylindrical micelles made of
N-Tetradecyl-N,N-Dimethyl-3-ammonio-l-PropaneSulfonate, and Sodium
Dodecyl Sulfate, in saline water, are used. The transisomer chmmophore
incorporates into the micelles modifying the solution viscosity and
viscoelastic spectra, which follows the Maxwell model at low and
intermediate frequencies. However, the effect of UV-irradiation on
rheological properties is not significant. Micro-rheological experiments
are performed with diffusive wave spectroscopy to obtain high-frequency
viscoelastic spectra to estimate the characteristic length scales of the
wormlike micellar network with the embedded chmmophore to understand its
rheological behavior better. Detailed interaction between the
chromophore and the micelles is obtained with (HM)-H-1-NMR and H-1 DOSY
NMR experiments to determine the chmmophore conformation into the
micelles and diffusivity of the isomers.
Filiaciones:
Rincon-Londono, Natalia:
Univ Nacl Autonoma Mexico, Inst Fis, POB 20-364, Mexico City 01000, DF, Mexico
Garza, Cristina:
Univ Nacl Autonoma Mexico, Inst Fis, POB 20-364, Mexico City 01000, DF, Mexico
Esturau-Escofet, Nuria:
Univ Nacl Autonoma Mexico, Inst Quim, POB 70-213, Mexico City 04510, DF, Mexico
Kozina, Anna:
Univ Nacl Autonoma Mexico, Inst Quim, POB 70-213, Mexico City 04510, DF, Mexico
Castillo, Rolando:
Univ Nacl Autonoma Mexico, Inst Fis, POB 20-364, Mexico City 01000, DF, Mexico
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