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Abstract

A variable long path gas cell was used to measure the sorption of organic vapors by a polymer slab. Unfilled polydimethylsiloxane (PDMS) slabs were cast and used to study the sorption of a series of aliphatic alcohols. The PDMS slab was suspended in the gas cell and exposed to low relative pressures of an alcohol vapor. The sorption rate of the alcohol vapor by the PDMS slab was obtained by measuring the decrease in the amount of free diffusant in the gas cell. The diffusion coefficients of the alcohols in the PDMS slab were then calculated from the curves of amount of diffusant sorbed versus time. The results show that the values of the diffusion coefficients at nearly infinite dilution, D0, for methanol, ethanol, 1-propanol, and 1-butanol are 1.01 x 10(-5), 0.61 x 10(-5), 0.54 x 10(-5), and 0.33 x 10(-5) cm2/sec, respectively. The isotherms for the sorption of the alcohols by the PDMS slab were also constructed from the data.

Determination of Diffusion Coefficients of Sodium p-aminosalicylate in Sheep Nasal Mucosae and Dialysis Membranes by Fourier Transform Infrared Horizontal Attenuated Total Reflectance Spectroscopy

“…8 The values of the diffusion coefficients obtained from these techniques agree well with previously reported values. Wurster, Buraphacheep, and Patel 2 used a horizontal attenuated total reflectance (H-ATR) cell to determine diffusion coefficients of neat liquids in semisolids.…”

Diffusion of Solvent in PDMS Elastomer for Micromolding in Capillaries

“…In Table 2 our results for the diffusion coefficient are given and compared with the data from the literature with which we find good agreement for ethanol and some deviation for 1-butanol. We note that the cross-linking (curing) of PDMS during preparation of the stamp does not necessarily lead to one and the same material in the different preparations and do not consider it meaningful to further analyze the differences of diffusion coefficients between this study and previous studies, [2][3][4][5]7 as the PDMS preparation is either different from our method or no information on the preparation method is available.…”

“…We are interested in the average mass flux through the channel walls into the PDMS. According to the 1-D diffusion assumption (3), this should follow a t -1/2 behavior. In Figure 2 the numerically calculated average nondimensional mass flux, m′* ) -Dt s /w 2 ∂F s /∂x* is plotted as a function of (t*) -1/2 for Dt s /w 2 ) 0.2.…”

“…With this method we have a simple way to indirectly measure the diffusion coefficient of different solvents in the PDMS membrane. Favre et al 2 used the vapor permeation technique to determine the diffusion coefficients of various alcohol vapors in PDMS as did Buraphacheep et al 3 but with the use of Fourier transform infrared spectroscopy as well. Muzzalupo et al 4 used a pulsed field NMR technique to examine the temperature dependence of self-diffusion of organic molecules in PDMS.…”

Microfluidic Systems for the Belousov−Zhabotinsky Reaction

“…Lu et al reported diffusion constants of 1.4 × 10 -5 to 2.2 × 10 -5 cm 2 /s for oxygen diffusion in silica-filled and unfilled PDMS films at room temperature . Buraphacheep et al measured slightly smaller diffusion constants for various alcohols . For the case of PDMS elastomers created from the Sylgard 184 kit, it is important to note that the starting material may contain oligomers with terminal Si−H and Si−CC groups that can possibly react with bromine in the illuminated samples.…”