Optical measurement of the swelling behavior of PDMS in organic solvent vapors

Abstract

In this paper, we present a new innovative method and device for measuring polymer swelling and deswelling using light interference in the spectral and time domains. The method of measurement is based on two-beam interference of light, and it allows the investigation of rapid changes of swelling and deswelling of the polymer layer in the Fabry-Perot cavity occurring within a few seconds, or less. We studied swelling and deswelling processes of constrained Polydimethylsiloxane (PDMS) layers in organic solvent vapors of isopropanol, acetone, and toluene. The swelling curves of PDMS in small concentrations of solvents and also the threshold values of vapor mass concentration at saturation in air were determined. The measured saturation values were 141 g/m3 for isopropanol, 745 g/m3 for acetone, and 399 g/m3 for toluene. With our method, it is possible to measure swelling of various polymers (even non-transparent), which will be equipped with a reflective surface.

Keywords

• Optical fiber sensor
• Polydimethylsiloxane
• Swelling
• Fabry-perot cavity
• Organic solutions