Layer preparation, immersion procedures

The casting procedure consisted of drawing an aqueous solution of PVA to a thin layer, and after an evaporation period, immersing in the complexing bath. The complexing bath used in our study was basically a saturated CuSO solution, with or without a series of possible additives. After a period of equilibration of over 24 hours, the membranes were dried and subjected to dry heat treatment,in order to stabilize the asymmetric structure obtained. The preparation conditions of several membranes prepared by this method are shown in Table V. 

The grafting to method was used to anchor polymer chains onto the surface of silica particles and silicon wafers (Scheme 1). The synthetic procedure starts with covalent grafting of GPS to the surface. A self-assembled monolayer of GPS on silicon wafer surfaces was prepared according to the procedure suggested by Luzinov [32], For this, Si wafers were immersed in a 1% GPS toluene solution for 15 h under dry Ar atmosphere (< 1 ppm H2O). After treatment, GPS modified wafers were washed 3 times in dry toluene under dry Ar atmosphere to avoid polymerisation of non-grafted GPS and precipitation of particles. Afterwards, the silanized wafers were washed 2 times with ethanol in ultrasonic bath for 5 min followed by drying with nitrogen flux. The thickness of the GPS layer was determined by null ellipsometiy. 

The impregnation of the layer is performed by immersing the plate in a solution of the silver salt in methanol, acetone or acetonitrile or by spraying the plate with one of these solutions. Preparative plates are usually treated with 1-20% silver nitrate solutions. For analytical Ag TLC, the concentration of silver nitrate varies in the range 0.5-10%. The impregnation procedures must be standardized to provide reproducible separation. Plates are left in the air for the solvent to evaporate and are usually activated prior to use (between 5 min and 1 h depending on the purpose) by heating at 110°C. 

B) Preparation of Diphenylmethane (M.). Use the apparatus shown in Mgure 46 without the separatory funnel. Place a pail on the base of the stand and arrange the flask so that it is well immersed in ice water. Use 25 g of benzyl chloride, 100 ml of benzene, and 10 g of anhydrous aluminum chloride. Add the chloride in five to six portions by raising the cork on top of the condenser momentarily, and observe the same procedure and directions as given in section (A). Use a separatory funnel to separate the benzene layer, and a distilling flask for the fractionation. The yield is 17-20 g. 

SAM Formation. SAMs of 11-MUA were prepared ex situ in 1-3 mM ethanolic solution of 11-mercaptoundecanoic acid, which was purchased at Sigma Aldrich. Two different substrates were used Au(lll)/mica and recrystallized gold foils. Typically, substrates are cleaned in piranha solution. This procedure was not possible for Au( 11 l)/mica, because it led to a separation of the gold layer from the mica substrate. Therefore, both substrates were cleaned in a UHV chamber by Ar+ -sputtering, followed by short annealing at 800 K to get a smooth surface. After removal from the vacuum chamber, it was immediately immersed into the solution. Typically samples remained for 48 h in the solution. After removal out of solution, the samples were rinsed with ethanol and dried with C02 - spray. 

A point often neglected is the handling procedure between preparation of the surface and immersing the specimen in the test medium. For instance, oxide film formation on oxide-passive materials and or tarnishing layers on copper or iron alloys formed at this stage can influence the electrochenucal behaviour considerably these chemical changes on the surface depend on such factors as temperature, humidity and time [5]. 

Lee et al. (2008) applied an in sitn interfacial polymerization procedure on the PES support for preparing composite nanoparticle-based membranes. In this procedure, commercial Ti02 nanoparticles of 30 nm were dispersed in an organic trimesoyl chloride (TMC) solntion. The PES support was first immersed in aqueous m-phenyl diamine with 0.05 wt% NaOH the excess reagent was removed from the surface so that a controlled reaction was obtained on subsequent immersion in the solution of TMC in 1,1-dichloro-l-fluoroethane. As a result, a thin modified layer with immobilized nanoparticles was obtained on the surface of the PES support. 

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