Spin coating techniques

The rqjroducibility of polymer film formation is greatly improved by the spin coating technique where the polymer solution is applied by a microsyringe onto the center of a rapidly rotated disk electrode Rather thick films can be produced by repeated application of small volumes of stock solution. A thorough discussion and detailed experimental description of a reliable spin coating procedure was given recently... 

Hui R, Wang Z, Yick S, Marie R, and Ghosh D. Fabrication of ceramic films for solid oxide fuel cells via slurry spin coating technique. J. Power Sources 2007 172 840-844. 

The spin coating technique of preparing PAMAM dendrimer samples for AFM is the best method to maintain undistorted dendrimer shape allows the visualization of isolated single dendrimer molecules. In spin coating, a dendrimer solution is rapidly spread across the sample surface and the majority of particles separate from one another. 

It is noted that the UV absorbance of the 10(g)-32(sc) sample decreased after the annealing treatment, as shown in Fig. 28a. Presumably, most polysilane chains lie down before annealing in the quartz substrate plane, as the film was prepared by the spin-coating technique. However, the thermal annealing treatment of semi-flexible 32 tends to orient some of the polymer chain segments perpendicularly and/or tilt them to the substrate plane, leading to the decrease in the apparent UV absorbance at 321 nm, as illustrated in Fig. 27. 

The kinked POOXPV polymer mentioned in Section 5 (Scheme 10) is blended with MEH-PPV in order to increase the EL intensity. The MEH-PPV/POOXPV blending ratios are 1/1, 1/5 and 1/10 by weight. The high quality films of the blend polymers are obtained from 1,2-dichloroethane solution by spin-coating technique. Figure 29 shows the structures of MEH-PPV and POOXPV. 

An alternative approach to producing a differently functional surface is to use spin coating techniques. This was done by Turner et al. [68], who spun cast layers of polystyrene onto a silica surface. They investigated the nature of the surface and of SDS adsorbed to that surface by neutron reflectivity and IR-ATR. A thin layer of polystyrene, 275 A, was established. The subsequent SDS adsorption was consistent with a monolayer 15 A thick and an adsorbed amount similar to that observed at the air-solution interface. Measurements above the cmc of SDS showed clearly the effects on the adsorption pattern of dodecanol impurities in the SDS. 

Polymer film electrodes are prepared either by evaporation technique or by -> electropolymerization. Redox polymers that are usually synthesized chemically are dissolved in a suitable solvent, placed as a droplet on the surface of a metal (or dip-coating, spin-coating techniques are applied) and the solvent is subsequently left to evaporate. The electrode can be used in other solvents in which the polymer is insoluble. Conducting polymer layers are usually developed by electropolymerization directly on the surface of the metal. 

Unlike parylenes, polyimides however, can also be prepared by a spin coating technique, and is investigated widely in literature.Only recently, several polyimides have been synthesized by vapor deposition polymerization technique. The preparation techniques and the properties of the films are discussed in the following sections. 

Rather than use a conventional phosphorus reactant, Schmutz et 81. relied on the polymeric reaction product of P2O5 + ethanol. Schmutz et al. also used Li00CCH3-2H20, Ti(OC2H5)4, and aluminum di-sec butoxide acetoacetic ester chelate to synthesize a precursor sol. The researchers used spin-coating techniques with the precursor sol to produce Lij 3 Alg Tij 7(P04)3 thin films on glass substrates at 650°C. The 300°C ionic conductivity was determined to be 4 x 10 S/cm. 

Magnetic electrode has been made of polycrystalline Ni plate. Copper has been used as non-magnetic metal and second electrode. Polymer film has been made by means of the spin-coating technique. The special semiconductor... 

A third common way of depositing ion conducting membranes is to use a spin coating technique. The specifics of this technique will depend on the viscosity... 

The spin coating technique has attracted interest, since it maintains many aspects of technical catalysts prepared by pore volume or incipient wetness impregnation, and simultaneously allows the interpretation and analysis in a similar way as the more well-defined model systems discussed above [30]. Here, a solution of the desired catalyst precursor is dropped onto a wafer covered with an oxide film, which is spun on a rotor to create a liquid layer of uniform thickness in order to mimic traditional wet impregnation preparation of catalysts. Control of the catalyst loading and particle size is to some degree achieved by varying the rotation speed, concentration, and vapor pressure of the solute. Still the method suffers, however, from many of the drawbacks associated with wet-impregnated model catalysts, which imparts detailed mechanistic studies. 

Following these recent successful developments, trilayer hybrid NC/polymer devices were reported, constituting a film of CdSe/ZnS NCs a few monolayers thick sandwiched between films of PVK (hole transporter) and butyl-PBD (electron transporter) [23]. All the layers were deposited by a spin-coating technique from dissimilar solvents (either organics or water). These devices showed 20 times the external quantum efficiency (0.2 %) and less than half the threshold voltage of a single-layer device based on the PVK/NC/PBD blend. These improvements upon going from a blend to a trilayer structure were attributed to more balanced carrier conduction to and enhanced recombination in the NC layer. 

The present discussion [47] deals with the formation of natural self-assembly of CuS nanoclusters in dielectric substrates of gum Arabica biopolymer. Low concentration of ammonium complex of copper oxide solution was dissolved in gum Acacia Arabica solution at 60°C and stirred. H2S gas was passed in the same environment for 1 minute. Heating the resulting solution to about 100°C evaporates any possible trace of ammonia. The resulting nanocomplex was caste in the form of very thin film by spin coating technique. The developed specimen was used for experimental investigations, namely TEM, XRD, and electrical experiments such as impedance spectroscopy, and the Arrhenius plot and I-V characteristics were measured in the applied field direction perpendicular to the 2-D plane. 

---