Investigation of Pore Size Distribution and Mechanical Properties of Porous Polydimethylsiloxane (PDMS) Structures Using Solvent Evaporation Technique

This paper reports a fast and straightforward method for controlling the pore size distribution and mechanical properties of porous polydimethylsiloxane (PDMS) structures. The solvent evaporation-induced phase separation is implemented for the fabrication of absorbent PDMS sheets. The ternary polymer solution containing PDMS, water (nonsolvent), and three different solvents are prepared. Tetrahydrofuran, Heptane, and Toluene are the solvents explored in this study. The stepping heat treatment is applied to the sample to control the solvent evaporation and trigger the phase separation. The pore morphology and pore size distribution are explored using the scanning electron microscope images captured from the internal surface. The results demonstrate that the pore microstructure is sensitive to the solvent used in polymer solution preparation. Besides, the mechanical properties of the porous PDMS sheets are characterized by tensile testing of the dog bone-shaped specimens cut from the sheets. The results indicate that the elastic modulus of the porous PDMS is dependent on the pore size distribution of the structure. Moreover, the mechanical properties and pore microstructure are shown to be dependent on the solvent type used in the mixture.