Partition, Reaction, and Diffusion Coefficients of Bromine in Elastomeric Polydimethylsiloxane

Abstract

Experiments and models were used to determine the extent to which aqueous bromine permeated into, and reacted with, the elastomer polydimethylsiloxane (PDMS). Thin films of PDMS were immersed in bromine water, and the absorbance of bromine in the aqueous phase was measured as a function of time. Kinetics were studied as a function of mass and thickness of the immersed PDMS films. We attribute the decrease of bromine in solution to permeation into PDMS, followed by a combination of diffusion, reversible binding, and an irreversible reaction with PDMS. In order to decouple the irreversible reaction from the reversible processes, kinetics were also studied for brominepassivated PDMS films. Fits of the models to a variety of experiments yielded the partition coefficient of bromine between the water and PDMS phases, the diffusion constant of bromine in PDMS, the irreversible reaction constant between bromine and PDMS, the molar concentration of the reactive sites within PDMS, and the on and off rates of reversible binding of bromine to PDMS. Developing a quantitative reaction−diffusion model accounting for the transport of bromine through PDMS is necessary for the design of microfluidic devices fabricated using PDMS, which are used in experimental studies of the nonlinear dynamics of reaction−diffusion networks containing Belousov−Zhabotinsky chemical oscillators.

Originating Point of Traveling Waves on a Spherical Field Dependent on the Nature of Substrate Surface

“…The adsorption of Br 2 into a hydrophobic material was reported in a previous study. 28,29 Additionally, a microfluidic device made of dimethylpolysiloxane, the main ingredient of silicone grease, acts as a reservoir for bromine and affects the BZ reaction. 30 A significant amount of Br 2 impregnated into silicone grease with a higher density may reduce the trigger of TWs from the plate because Br − , as the inhibitor of the BZ reaction, is produced from Br 2 around the plate with silicone grease.…”

Predicting Corrosion Delamination Failure in Active Implantable Medical Devices: Analytical Model and Validation Strategy

“…Up to this point, diffusion out of the aqueous phase was not considered in most studies. Only a single paper has described diffusion of aqueous bromine in PDMS [ 24 ], so far.…”