Photochromic Hybrid Organic−Inorganic Liquid-Crystalline Materials Built from Nonionic Surfactants and Polyoxometalates: Elaboration and Structural Study

Andreas S. Poulos (1) , Doru Constantin (1) , Patrick Davidson (1) , Marianne Impéror-Clerc (1) , Brigitte Pansu (1) , Pierre Panine (2) , Lionel Nicole (3) , Clément Sanchez (3)

1 LPS - Laboratoire de Physique des Solides
2 ESRF - European Synchrotron Radiation Facility
3 LCMCP (site Paris VI) - Laboratoire de Chimie de la Matière Condensée de Paris (site Paris VI)

This work reports the elaboration and structural study of new hybrid organic−inorganic materials constructed via the coupling of liquid-crystalline nonionic surfactants and polyoxometalates (POMs). X-ray scattering and polarized light microscopy demonstrate that these hybrid materials, highly loaded with POMs (up to 18 wt %), are nanocomposites of liquid-crystalline lamellar structure (Lα), with viscoelastic properties close to those of gels. The interpretation of X-ray scattering data strongly suggests that the POMs are located close to the terminal −OH groups of the nonionic surfactants, within the aqueous sublayers. Moreover, these materials exhibit a reversible photochromism associated to the photoreduction of the polyanion. The photoinduced mixed-valence behavior has been characterized through ESR and UV−visible−near-IR spectroscopies that demonstrate the presence of WV metal cations and of the characteristic intervalence charge transfer band in the near-IR region, respectively. These hybrid nanocomposites exhibit optical properties that may be useful for applications involving UV-light-sensitive coatings or liquid-crystal-based photochromic switches. From a more fundamental point of view, these hybrid materials should be very helpful models for the study of both the static and dynamic properties of nano-objects confined within soft lamellar structures.

Domaines: Matière Molle [cond-mat.soft]

Andreas S. Poulos, Doru Constantin, Patrick Davidson, Marianne Impéror-Clerc, Brigitte Pansu, et al.. Photochromic Hybrid Organic−Inorganic Liquid-Crystalline Materials Built from Nonionic Surfactants and Polyoxometalates: Elaboration and Structural Study. Langmuir, 2008, 24 (12), pp.6285-6291. ⟨10.1021/la8004322⟩. ⟨hal-00338460⟩