title: Influence of phase transition and photoisomerization on interfacial rheology.
abstract: This paper presents the shear responses and interfacial rheology of photosensitive monolayers. Langmuir films of a fatty acid containing an azobenzene moiety that can undergo trans-cis photoisomerization have been investigated for their structural and dynamical properties. The cis conformation produces a structureless, Newtonian film that cannot be oriented by surface flows. Transforming the molecule to the trans configuration produces a well-packed film that responds to flow with an anisotropic and non-Newtonian character. The trans state supports two separate phases, a low-pressure phase where the azobenzene group is free to rotate, and a high-pressure phase where this moiety is frozen in place.
authors.affiliation: Department of Chemical Engineering, Stanford University, California 94305, USA.
authors.forename: Kang Sub
authors.initials: KS
authors.lastname: Yim
authors.forename: Gerald G
authors.initials: GG
authors.lastname: Fuller