Coating coverage techniques

Dip and Spin Coating. The dip coating technique described for webs can also be used to coat discrete surfaces such as toys and automotive parts. The surface to be coated is suspended on a conveyor and the part dipped into the coating solution. The surface is then removed, the coating drains, then levels to give the desired coverage. The object is then dried or cured in an oven. 

After the precursor stock solution is prepared, various techniques can be used to coat the substrate, depending on the solution viscosity, required film thickness and coverage. The most common methods in the semiconductor industry are spin- and dip-coating. Other processes that are used for deposition include spray coating and stamping. A summary of the uses, limitations, and advantages of the various thin film deposition methods is reported in Table 2.2. 

Kobayashi et al. [91] recently synthesized a phase that is comprised of thiol-modified gold-coated polystyrene particles. An increase in the selectivity of the anthracene-phenanthrene pair was observed on the Cis-Au particle when compared with a traditional monomeric Cis phase with a surface coverage of 3.0 p,mol/m. This isomer pair is not the ideal choice for the determination of shape selectivity however, this synthetic technique should in general lead to dense, ordered phases that are anticipated to yield relatively highly shape-selective chromatographic separations. 

According to results obtained with different dsDNA concentrations, 16 ig/mL was chosen as the optimum concentration for full coverage surface of PGE by dip-coating technique, due to its having better reproducibility and sensitivity. 

The potential benefits of CVD over other film deposition techniques are that CVD-derived films can be deposited under conditions that give conformal coverage, they can be deposited at low temperatures, there can be a high level of compositional control, thin layers can be deposited, the technique can be scaled to coat large areas uniformly, and there is also the possibility for area-selective deposition13 as a result of the chemical nature of this process. The details of CVD and related chemical deposition processes such as atomic layer epitaxy (ALE), organometallic vapor-phase epitaxy (OMVPE), and others have been described elsewhere.6... 

Surface coverage values for trans-Os11(MeoPhPT (PVP)CI2 varied from 10- to ca. 2 x 10 mol/cm which, depending upon the PVP film thickness, indicated that up to 50% of the pyridine groups were metallated. This value is considered to be a lower limit since the pre-soaking technique (see experimental section) probably removes a fraction of the PVP coating from the surface. 

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