title: Local viscosity and solvent relaxation experienced by rod-like fluorophores in AOT/4-chlorophenol/m-xylene organogels.
abstract: Organogels prepared from AOT/4-chlorophenol/m-xylene are immobile in the macroscopic sense, with a well-characterized internal structure. However, the molecular level dynamics inside the gels is not too clear, although a very slow structural relaxation has been reported previously. Using a set of rod-like fluorophores, we find that the rotational mobility of a small guest molecule inside the gel can be extremely fast, indicating presence of sufficiently low-microviscosity domains. These domains consist of m-xylene solvent molecules trapped in the interstices of fiber bundles comprising columnar stacks of 4-chlorophenol surrounded by AOT molecules. However, interstitial trapping of m-xylene does retard its own dynamics, which explains the slow solvent relaxation inside the gels. Hence, the state of m-xylene in the organogel may be characterized as "bound", in contrast to the "free" state in neat m-xylene.
authors.affiliation: Department of Chemistry, University of Calcutta, 92, APC Road, Kolkata 700009, India.
authors.forename: Manika
authors.initials: M
authors.lastname: Dandapat
authors.affiliation: Department of Chemistry, University of Calcutta, 92, APC Road, Kolkata 700009, India. Electronic address: dmandal.chemistry@gmail.com.
authors.forename: Debabrata
authors.initials: D
authors.lastname: Mandal
keywords: Microviscosity; Organogel; Solvent relaxation