Dual functionality coatings

Dual functionality coatings differ from dual cure coatings in that they contain functional groups of different kinds. In the first step, partial crosslinking is accomplished through exposure to UV light, in the second step another component, for example an epoxide, is cured thermally through the activation of a latent catalyst. 

Microbiocides may be toxic to humans therefore, care must be taken when used. When selecting the microbiocide, the field engineer can obtain pertinent information on chemicals from the service company providing the chemicals. The microbiocide selected must be compatible with the system in which it is being used. Some chemicals such as quaternary amines have dual functions one as microbiocides and the other as film-forming corrosion inhibitors. Insufficient concentrations of this type of chemical may not be enough to coat the whole surface of metal and can cause pitting corrosion. The selection must also depend on chemicals that can produce the desired control in minimum time limits and... 

To improve chromatographic separation, another analytical column could be used in addition to the monolith (Xu et al. 2006). The monolith column served as an extraction column only. Hsieh et al. (2000, 2002) utilized a polymer-coated mixed function (PCMF) Capcell C8 column (4.6 x 50 mm, Phenomenex) to provide dual functions—online plasma extraction and analyte separation. The silica was coated with a polymer containing both hydrophilic polyoxythylene and hydrophobic groups. The diluted plasma samples (1 1 to 1 3) were injected directly. No column deterioration was observed after 200 injections. 

Similar dual functionality exists for many of the reverse phase packing materials (Fig. 5). Due to steric hindrance, the silica support is incompletely coated with the octadecyl molecules. The exposed silica groups serve as strong adsorption sites but the effect may be minimized by the addition of an organic acid to the mobile phase (46). 

Fig. 10 Example of a contact-killing and microbe-releasing surface. The scheme shows the design of a two-level dual-functional antibacterial coating containing both quarternary ammonium salts and silver. The coating process begins with LbL deposition of a reservoir made of bilayers of PAH and PAA. (A) Cap region made of bilayers of PAH and SiC>2 nanoparticles (NP) is added to the top. (B) The SiC>2 nanoparticle cap is modified with a quarternary ammonium silane (QAS) PEM polyelectrolyte multilayer. (C) Ag+ is loaded into the coating using the available unreacted carboxylic acid groups in the LbL multilayers. Scheme was reproduced from [138]...

Besides the most important area of surface coatings, the use of photopolymers as photoresists in the manufacture of printed circuits is well established. Photoimaging with aryldiazonium salt photoinitiators and multifunctional cresol-novolac epoxides was first described by Schlesinger Crivello has mentioned several new photoresists based on the photopolymerization of epoxides with onium initiators Meier and Zweifel have shown that iron arene salts in combination with multifunctional cresol-novolac epoxides yield photoresists with high resolution and contrast. Dual functional epoxides (cf. Sect. 5) containing chalcone groups as light-sensitive units have been described as suitable photoresists especially... 

Park, J. and McShane, M.J. (2010) Dual-function nanofilm coatings with diffusion control and protein resistance. ACS Applied Materials Interfaces, 2 (4), 991-997. 

Cyastat AA-SN used in surface coatings and other materials serves a dual function, acting as a dispersant as well as an antistatic agent. 

There is now a search for less toxic, greener alternative corrosion inhibitors. Chromates have combined effectiveness with relatively low cost. Sinko has reviewed the quality parameters needed for corrosion inhibitors in coatings, and generally concluded that inorganic non-chromate inhibitors such as phosphates, molybdates, borates and silicates are inferior to chromates. Rare earth salts have been proposed and show promise as alternative corrosion inhibitors, and we have been developing rare earth carboxylates as potential dual function inhibitors combining the roles of the rare earth and the aromatic carboxylates. If rare earth-based corrosion inhibitors are to be used, there is a need to understand the chemistry of the elements and of the inhibitors. 

Lee KS, Myung ST, Amine K, Yashiro H, Sun YK (2009) Dual functioned BiOF-coated Li [Lio.i A1o.o5Mi>i. 85]04 for lithium batteries. J Mater Chem 19 1995-2005... 

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