In-situ phosphatizing coatings

Chrome-Free Single-Step In-Situ Phosphatizing Coatings... 

Neuder H., Sizemore C., Kolody M., Chiang R., Lin C.T (2003), Molecular design of in situ phosphatizing coatings (ISPCs) for aerospace primers , Pwg. Org. Coat, 47,225. 

Other forms of coating systems which contain corrosion inhibitors include in-situ phosphatising coatings such as those described by Neuder et al. [126] where functionalised aryl-phosphonic and arylphosphoric acids were added to an epoxy primer. The inhibitors were shown to deposit uniform metal-phosphate products on the substrate surface and provide a similar level of performance to chromate-inhibited control samples when tested over 3000 h in a neutral salt spray test. 

An extraordinary way of stabilizing RUO2-coated CdS colloids for H2 generation was chosen by Fendler and co-workers The colloidal particles were generated in situ in surfactant vesicles of dioctadecyldimethylammonium chloride and dihexa-decyl phosphate. Thiophenol as a membrane permeable electron donor acted as a sacrificial additive. Later, a surface active re-usable electron donor (n-C,gH3,)2N — (CHj)—CH2—CHj—SH, Br was incorporated into the vesicles. Its R—SS—R oxidation product could be chemically reduced by NaBH to regenerate the active electron donor. The H2 yields in these systems were only 0.5 %. However, yields up to 10% were later reported for a system in which CdS was incorporated into a polymerizable styrene moiety, (n-C,jH3jC02(CH2)2) N (CH3) (CH2CgH4CH=CH2>, CP, and benzyl alcohol was used as the electron donor. 

Two recent studies provide more data on cellulose derivatives. Ranga Rao and Buri [86] measured in situ the adhesiveness of glass beads (as a model) and aspirin crystals coated with the polymers to be tested on the rat stomach or jejunum mucosae. The percentage of particles retained on the tissue upon washing by dilute HC1 (for the stomach) or a phosphate buffer (for the jejunum) was considered to be an index of bioadhesion (Table 17). 

Other anion-exchange resins have been developed which do not suffer from this drawback. We routinely now use polyethyleneimine (PEI) columns for the separation of oligonucleotides. PEI columns can be prepared by coating silica particles in situ with polyethyleneimine (4). The original protocol recommended an ammonium sulphate gradient in phosphate buffer in the presence of methanol for the separation of oligonucleotides. We run commercially available PEI wide pore columns with the same buffer system as described for the SAX columns that is solvent A, 1 mM potassium phosphate, pH 6.3, 60% (v/v) formamide and solvent B, 0.3 M potassium phosphate. pH 6.3, 60% (v/v) formamide. 

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