Considering their specific structure, porous polymers have high adsorptive capacity, high flexibility, high surface area, and low gas resistance compared to the bulk material. These properties of porous media have great potential for different fields, such as oil/water absorption, separation, energy storage, wearable electronics, biomedical, and many other applications. Polydimethylsiloxane (PDMS) is a non-toxic, organic elastomer that has received growing attention over the past few years. This material has been widely utilized in conductors, strain sensors, and biomedical applications due to the outstanding viscoelastic and biocompatible properties. Flexible conductors and strain sensors are the most important fields in which the mechanical or the electrical properties of PDMS can be modified by providing a porous structure. Recent studies have been performed to create porous PDMS by direct templating, emulsion templating, gas foaming, and phase separation techniques. It has been reported that different pore structure and morphology can be achieved by these methods. It is important to develop newer and more flexible methods for obtaining porous PDMS with tailored microstructure and properties, including pore size, porosity, and mechanical properties.

This paper presents the fabrication and mechanical characterization of porous PDMS plates. The framework for obtaining porous PDMS is based on the solvent evaporation induced phase separation technique. A mixture of PDMS, water, and solvent with different concentrations is prepared. The three phases are stirred to reach a stable highly viscous solution. The prepared mixture is poured into a 1 mm thick mold. Then, the solvent and water are evaporated during a curing cycle by applying a stepping heat treatment. The porous PDMS plates with a wide range of pore sizes are fabricated by controlling the ratio of water to the solvent in the mixture. The confocal microscopy images are used to characterize the average pore size and the pore size distribution in the structures. The porosity of the samples is also evaluated by measuring the volume using the density cup. Dogbone samples following ASTM standard D412 are cut from the porous plates by utilizing a designed cutting die and mechanical press. To evaluate the mechanical behavior of the porous structures, the specimens are tested under tensile loading. The effect of the average pore size on the mechanical properties of the structure is investigated. The results demonstrate the ability of the proposed solvent evaporation method to control the stiffness of the porous structure by changing the water to the solvent ratio in the mixture.


Manufacturing of Porous Polydimethylsiloxane (PDMS) Plates Using Solvent Evaporation Induced Phase Separation Technique

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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