3M membranes

Proton conductivity of PFSA membranes. Influence of polymer EW and hydration number (A) of 3M membranes at 80 °C.The conductivity of perfluorobutane sulfonic acid with A = 2, 3, 5, 9 H2O/ SO3H is shown for comparison (Source 3M). 

Figure 29 The intensity ot the DMPO/OH adduct as a tunction ot irradiation time tor the indicated membrane concentrations is shown tor Nation in (a), tor stabilized Nation in (b), tor 3M membranes in (c), and tor Aquivion membranes in (d). The thicker black line In each case shows the formation ot hydroxyl radicals in the absence ot membranes. Data were normalized to the intensity measured after 30 s ot UV irradiation at 300 K in the absence ot the membrane.

Glass electrodes are used for the analysis of hydrogen ions various other types of ion-selective electrodes are used for the other ions. Electrodes with ion-selective solvent membranes have become very popular. These electrodes are made in the form of thin glass capillaries (about 1 rm in diameter), which in the lower part contain a small volume of a liquid that is immiscible with water the remainder of the capillary is filled with electrolyte solution (e.g., 3M KCl). 

Ag AgCl KClsat 3M KC11 sample solution membrane inner filling solution AgCl Ag... 

Researchers at 3M have been able to increase catalytic activity with nanotextured membrane surfaces that employ tiny columns to increase the catalyst area. Other materials include nonprecious metal catalysts such as cobalt and chromium along with particles embedded in porous composite structures. 

The nanostructured thin-film electrode was first developed at 3M Company by Debe et al. [40] and Debe [41], who prepared thin films of oriented crystalline organic whiskers on which Ft had been deposited. The film was then transferred to the membrane surface using a decal method, and a nanostructured thin-film catalyst-coated membrane was formed as shown in Figure 2.10. Interestingly, both the nanostructured thin-film (NSTF) catalyst and the CL are nonconventional. The latter contains no carbon or additional ionomer and is 20-30 times thinner than the conventional dispersed Pt/ carbon-based CL. In addition, the CL was more durable than conventional CCMs made from Pt/C and Nation ionomer [40]. 

Fig. B.5 Cartoon depiction of the Western Biot sandwich. The gei is piaced with the membrane between a set of sponge pad and 3M papers on either side and the transfer is done with the membrane on the negative eiectrode.

High concentration of nontargeted ionic contaminants may reduce the efficiency of the 3M Empore extraction disk. Due to the high loading capabilities of the Empore membranes, the radionuclide concentration on the filters must be monitored to ensure that the membranes do not exceed the limits for low-level radioactive waste. 

To achieve the mechanical strength needed for use as a membrane, a microporous polyethylene support was used. The support, obtained from 3M (Minneapolis, MN), was approximately 20 microns in thickness and was 83% porous. The liquid monomer mixtures were applied to the support with a wiped film method and subsequently polymerized with UV irradiation at 365 nm and 2.0 mW/cm2 for 2 hours. After polymerization, a solid transparent film was obtained. To allow unreacted monomer and oligomer to leave the film, it was placed into chloroform for three days, with fresh chloroform exchanges once per day. After the chloroform exchanges, the film was allowed to dry in the chemical hood. 

Selectivity coefficients obtained by SSM employing modified (membrane conditioned in interfering ion solution (10-3M NaN03)) and classical (membrane conditioning in primary ion solution (10 iM AgN03)) experimental setups... 

Ion Membrane conditioned in 1(T3M NaN03 Membrane conditioned in 10 3M AgNOa ... 

Note Transport conditions source phase, MN03 = 0.1 M membrane-phase carrier 10 3M in CH2C12 receiving phase, deionized water. 

Fig. 20. Absorption spectra of PdLCl and the interfacial aggregates of ternary PdL-Dz complexes measured by the CLM method. [PdLCl]in t = 5.6 x 10 5M, [pyridazine] = 2.0 x 10 4M, [pyrimidine] = 8.0 x 10 3M, [pyrazine] = 8.0 x 10 5M, [C104 ] = 0.1 M, [Cl ] = 0M, pH 2.0. The left structure shows a probable unit of the membrane-like aggregate formed in pyrazine complexes.

Low-symmetry crown ethers, possessing (3m + )-crown- z scaffolds, show a less pronounced binding ability than symmetrical crown ethers, but display much higher selectivities for specific cations . For instance, polymer membrane thallium(l)-selective electrodes based on dibenzo-crown ether derivatives 67 have been developed <1996CCR171>, because of the environmental and biological implications associated with the poisoning of Tl+ ions. 

Perfluorinated membranes are still regarded as the best in the class for PEM fuel cell applications. - These materials are commercially available in various forms from companies such as DuPont, Asahi Glass, Asahi Chemical, 3M, Gore, and Sol-vay. Perfluorosulfonic acid (PFSA) polymers all consist of a perfluorocarbon backbone that has side chains terminated with sulfonated groups. 

Five millimeter diameter disks of a porous polyethylene membrane, used as a window material in disposable FT-IR cards manufactured by 3M Corp. (Fisher Cat. 14385-861), were prepared by pre-wetting with 2 pi of methanol. A 1 pi aliquot of the aqueous protein solution was then added, and the membrane allowed to air dry at room temperature, before addition of 2 pi of matrix solution and final air drying. For those samples that were washed, after the protein solution had dried the membrane spot was vortexed in an aqueous 50% methanol solution for 30 seconds and air dried before addition of the matrix solution. 

Several membranes (Cg and Cjg and the disposal IR card are a 3M product purchased from Fisher Scientific, the 113-2 and 1222 membranes were a gift from 3M) were tested ... 

M Empore Strontium Rad Disks (47 mm of diameter) were used to concentrate the strontium contained in the samples. The membrane eluates were mixed with scintillating cocktail Optiphase Hisafe 3 in 20 mL polyethylene vials from PerkinElmer M. 

Empore 3M Particle-loaded membranes, disks PIPE, PS-DVB, silica lEX, AF... 

Most commercial systems like Mustang from Pall and Sartobind from Sartorius make use of functionalized microporous membranes. The fibrils reinforced membranes are (pleated) layered around a porous core. The feed is forced to permeate through the membranes in radial direction. This approach results in high area to volume ratio. The 3M and Mosaic Systems approach is different. Instead of functionalization of a porous support they make use of already functionalized beads, which are embedded in a porous support. In this approach, the beads are responsible for the capacity and selectivity where the porous matrix controls the hydrodynamics. The 3M modules consist of stacked flat sheet or pleated membranes, while Mosaic Systems makes use of porous fibers in which the active particles are embedded (Figure 3.23). 

FIGURE 27.32 Fuel cell polarization curve of a 50 cm MEA made with the new 3M cast membrane (30 pm). (From 3M, www.3m.com.)... 

A typical extraction sequence is similar to the traditional SPE, although 500 pL of the appropriate solvent is sufficient for disk conditioning and extraction of the analytes. Several types of disk extraction media are commercially available in different dimensions depending on the application and sample volume. The most prevalent are paper-based, membrane-based, glass fiber-based, and PTFE-based products. Commercially available products are Speediscs by Baker, Empore by 3M, Novo Clean by Alltech, and SPEC by Ansys Technol. 

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