Polydiacetylene Langmuir-Blodgett films

Geiger E, Hug P, Keller BA. Chromatic transitions in polydiacetylene Langmuir-Blodgett films due to molecular recognition at the film surface studied by spectroscopic methods and surface analysis. Macromol Chem Phys 2002 203 2422-2431. 

Figure 7.33 Langmuir-Blodgett film formed by polydiacetylene (a) schematic diagram of Langmuir trough and (b) structure of a typical polydiacetylene film. (After Williams, 1983.)... 

Recently, liu et al. [33, 34] reported an absolute asymmetric transformation when the achiral monomer 10,12-tricosadiynoic acid was deposited on an aqueous solution containing Cu + ions. The monolayer was then transferred to a solid support as a Langmuir-Blodgett film, followed by photo-polymerization to yield a stable homochiral polydiacetylene as helical fibers. 

Despite their potential importance, there are few spectroscopic studies of polymerizable surfactants. The only well-characterized polymerized surfactants are the polydiacetylenic fatty acids. The polymerization mechanism (1,4 addition) was only recently discovered as a result of studies on crystals of non-surfactant monomers which become brightly colored on polymerization [1], indicating the formation of polymer concurrent with a solid-solid phase transition. Several groups, particularly that of Ringsdorf, have pioneered the study of polydiacetylenic fatty acids [2-5]. A significant amount of spectroscopic work has been done on non-surfactant polydiacetylenes [6-9]. In addition, Lando and co-workers have used electron diffraction from mono- and bilayers of fatty acids to establish the conformation of the diacetylene backbone chains in this ordered surfactant system [10,11], and others have performed Raman spectroscopy on Langmuir-Blodgett films of similar surfactants [12]. This provides one with a powerful "basis set" of information from which to study other polydiacetylenic systems. 

N. Mino, H. Tamura, and K. Ogawa, Analysis of color transitions and changes on Langmuir-Blodgett films of a polydiacetylene derivative, Langmuir 7 2336 (1991). 

KAJZAR F., ROTHBERG L., ETEMAD S., CHOLLET P.A., GREC D., BOUDET A. and JEDJUT., (1988a), Saturation Absorption and Kerr Susceptibility in Polydiacetylene Langmuir-Blodgett Film" Opt. Commun., 66, 55-58. 

Several possible applications of Langmuir-Blodgett (LB) films, are ruled out at the moment by their poor crystallinity. Homoepitaxy and in-plane anisotropy are two phenomena which could be used to achieve better order, but while they have been observed on many occasions there is little agreement on the conditions required to reproduce them. This paper discusses the present state of the author s research. Homoepitaxy can now be achieved routinely with a number of materials, while in-plane anisotropy has been shown to produce significant ordering, although in a more more complicated manner than previously thought. Possible future directions for polydiacetylene LB films are discussed. 

Kajzar, F. and Messier, J., Resonance enhancement in cubic susceptibility of Langmuir—Blodgett multilayers of polydiacetylene, Thin Solid Films, 132, 133, 1985. 

Figure 7 Principle of Langmuir-Blodgett thin film deposition. The upper part of figure show a polydiacetylene monomer (left) and polymer (right) bilayer P, pressure sensor MB, mobile barrier S, substrate (Kajzar and Messier (198 c)).

Induced Optical Second Harmonic Generation and Polarization Effect in Polydiacetylene Langmuir-Blodgett Multilayers" Thin Sol. Films, I32, 1-10. 

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