[3] Bubble nucleation in the surfactant stabilized polyol-CO2 mixtures: Insights from a classical density function theory study
Date:
Polyol based foams are widely sought-after materials for manufacturing thermal insulators, high resilience foam seating, adhesives, hard plastics for electronic instruments, etc. The polyol foams are produced by the reaction of di-isocyanate with polyol to form polyurethane and water. Some amount of isocyanate reacts with water to produce CO2. The generated CO2 nucleates into bubbles within the polymer matrix, forming a foam. Silicone-polyether(SPE) surfactants, made of poly dimethyl-siloxane backbone and polyether branches, are commonly used to stabilize the foam formulation. The SPE surfactants reduce interfacial tension between polyol-CO2 interface, promotes bubble generation and impacts the foam cell size. It is also known that the composition of SPE surfactant significantly influences its role in stabilizing the foam formulation as well. However, the physical mechanism of how these SPE surfactants affect the nucleation and stability of the bubbles is not well understood. In this talk, using classical density functional theory models, we propose design principles for SPE surfactants and elucidate the mechanism through which they lead to foams with improved physical properties.
*This work was funded by the Dow Chemical Company