Porous Polymer Structures with Tunable Mechanical Properties Using a Water Emulsion Ink

Area of Science:

• Materials Science
• Polymer Chemistry
• Additive Manufacturing

Background:

• Polydimethylsiloxane (PDMS) is a versatile polymer with tunable properties.
• Engineered porosity in PDMS enhances its mechanical characteristics and expands its applications.
• Controlling pore formation is key to tailoring PDMS material performance.

Purpose of the Study:

• To investigate the use of transient liquid phase water as a pore-forming agent for PDMS.
• To optimize PDMS-to-water ratios for improved mechanical properties and pore stability.
• To assess the suitability of water-emulsion PDMS foams for additive manufacturing.

Main Methods:

• Varying deionized water to PDMS precursor ratios (100:0 to 10:90) during blending and curing.
• Characterizing mechanical properties (Young's Modulus, energy absorption, compressive strength).
• Evaluating pore stability at different storage temperatures and incorporating fumed silica for rheological modification.

Main Results:

• The PDMS-to-water ratio of 65:35 yielded optimal mechanical properties, including a 31.46% increase in Young's Modulus compared to bulk PDMS.
• Optimal storage at -60 °C ensured pore stability for three weeks.
• 9 wt% fumed silica provided ideal viscosity (10,290 Pa·s) for paste extrusion additive manufacturing, exhibiting shear-thinning and thixotropic behavior.

Conclusions:

• Water serves as an effective pore-former for PDMS, enabling the creation of materials with enhanced mechanical properties.
• Engineered porous PDMS foams are suitable for additive manufacturing processes.
• These materials hold potential for applications in aerospace, medical devices, and defense, including sensors and lightweight structures.