Polymer films Langmuir-Blodgett technique

Here, we demonstrate that oriented PAV films with well-developed -conjugated system can be fabricated through the regulation of orientation of precursor polymer chains by use of the Langmuir-Blodgett technique, and that large and anisotropic third-order optical nonlinearity was observed in the oriented PAV films. 

Paddeu S., Ram M. K., and Nicolini C., Investigation of ultra-thin films poly (ortho)-anisidine conducting polymer obtained by the Langmuir-Blodgett technique J. Phys. Chem. B., 101, 4759-4766, 1997. 

Polymerization of extremely thin polyacetylene films (< 1 pm) on crystal surfaces by epitaxial growth (e.g. on frozen benzene) [11] also induces orientation in the deposited polymer layer. Substituted polypyrrole films with a high anisotropy can be produced by the Langmuir-Blodgett technique [12]. 

The precursor polymer can be fabricated, e.g., by spin-coating, dipcoating or by Langmuir-Blodgett techniques into thin films. The pyro-... 

The methods commonly used for chain alignment in polymer films have been reviewed [34]. They comprise the Langmuir-Blodgett technique, rubbing of the film surface, mechanical stretching of the film, and orientation on prealigned substrates. As an example, electroluminescence spectra of the oriented substituted poly(p-phenylene) presented in Chart 6.5 are shown in Fig. 6.9 a [35]. 

We have applied high-precision diffraction analysis to monomers, oligomers, and polymers based on thiophene residues, in the form of single crystals, of powders, of cast thick films, and even as thin films prepared using the Langmuir-Blodgett technique. Preliminary results encourage us to perform further detailed studies on diffraction techniques suitable for well-ordered thin films, which are of interest for non-linear optics and for electronic applications. 

The precursor polymer can be fabricated, e.g., by spin-coating, dip-coating, or by Langmuir-Blodgett techniques into thin films. The pyrolysis of the materials is performed in high vacuum at temperatures of 180-300 °C for 12 h. In the final step, hydrogen chloride and tetrahydrothiophene will be removed. 

The Langmuir Blodgett technique offers the unique advantage to cover holes in perforated substrates. It has been shown, that films of tethered polyisoprenes with photoreactive side groups can be cross linked on the water surface via irradiation [27]. These cross-linked films of 40 nm thickness can be transferred to grids and perforated substrates and can span holes of up to 300 jum in diameter. Since these freely suspended films are made out of a cross-linked polymer melt, they show rubber elastic behaviour. 

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