Polymer films deposition techniques

The synthesis of intermediary inorganic sols or polymers in solution whose rheological properties may be attractive for the film deposition techniques such as spin coating or the spinning of fibers. 

POEA), a conducting polymer. The measurements were carried out using both solution and polymer films deposited by the self-assembly technique (Paterno and Mattoso, 2001). Figure 16.21 presents the Raman spectra of FA, POEA, and POEA/ FA complexes in different concentrations of FA. 

A variation of the experimental methods described above is the xerographic discharge technique which is gaining wide acceptance in the study of polymeric systems. The polymer film deposited on a metallic substrate is corona charged and... 

Plasma polymerization is a solvent-free process that can be used to rapidly deposit thin polymer films onto a wide variety of substrates at room temperature (214,215). Monomer vapor is exposed to an electric field, and the resultant reactive fragments recombine to form polymer films. This technique is used for a wide... 

This versatile technique was further extended into preparing a wide range of reactive coatings within complex confined microgeometries. The ability of this process to coat reactive polymer films within previously assembled devices was successfully demonstrated (Figure 5) (5/). The polymer films deposited within the microchannels were able to maintain reactivity towards their corresponding binding partners. Compared to conventional solution-based methods, this method provides a simple route that is well-defined, permanent and is not limited to short term applications. 

Electrochemical polymeriza tion of heterocycles is useful in the preparation of conducting composite materials. One technique employed involves the electro-polymerization of pyrrole into a swollen polymer previously deposited on the electrode surface (148—153). This method allows variation of the physical properties of the material by control of the amount of conducting polymer incorporated into the matrix film. If the matrix polymer is an ionomer such as Nation (154—158) it contributes the dopant ion for the oxidized conducting polymer and acts as an effective medium for ion transport during electrochemical switching of the material. 

Since multiple electrical and optical functionality must be combined in the fabrication of an OLED, many workers have turned to the techniques of molecular self-assembly in order to optimize the microstructure of the materials used. In turn, such approaches necessitate the incorporation of additional chemical functionality into the molecules. For example, the successive dipping of a substrate into solutions of polyanion and polycation leads to the deposition of poly-ionic bilayers [59, 60]. Since the precursor form of PPV is cationic, this is a very appealing way to tailor its properties. Anionic polymers that have been studied include sulfonatcd polystyrene [59] and sulfonatcd polyanilinc 159, 60]. Thermal conversion of the precursor PPV then results in an electroluminescent blended polymer film. 

Such effects are observed inter alia when a metal is electrochemically deposited on a foreign substrate (e.g. Pb on graphite), a process which requires an additional nucleation overpotential. Thus, in cyclic voltammetry metal is deposited during the reverse scan on an identical metallic surface at thermodynamically favourable potentials, i.e. at positive values relative to the nucleation overpotential. This generates the typical trace-crossing in the current-voltage curve. Hence, Pletcher et al. also view the trace-crossing as proof of the start of the nucleation process of the polymer film, especially as it appears only in experiments with freshly polished electrodes. But this is about as far as we can go with cyclic voltammetry alone. It must be complemented by other techniques the potential step methods and optical spectroscopy have proved suitable. 

Laser ablation of polymer films has been extensively investigated, both for application to their surface modification and thin-film deposition and for elucidation of the mechanism [15]. Dopant-induced laser ablation of polymer films has also been investigated [16]. In this technique ablation is induced by excitation not of the target polymer film itself but of a small amount of the photosensitizer doped in the polymer film. When dye molecules are doped site-selectively into the nanoscale microdomain structures of diblock copolymer films, dopant-induced laser ablation is expected to create a change in the morphology of nanoscale structures on the polymer surface. 

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