Sustainable formulation strategies for polyurethane foams: Effects of silicone surfactants on morphology and functionality

• Comparison of l-3002, l-3627, l-3639 shows unique foam structure effects. • Surfactant choice aligned with VOC rules boosts sustainable foam design. • L-3627 improves foam strength, stability, and heat resistance at 1 %. • Surfactants underperformed at 110, showing need for reactive tuning. • L-3639 gave balanced reactivity, keeping foam openness and airflow steady. Polyurethane (PU) foams are widely used in industries like automotive and bedding, where performance relies heavily on foam morphology and mechanical properties. Silicone-based surfactants play a key role in stabilizing foam structure during production by reducing surface tension and influencing characteristics such as cell openness and firmness. However, the molecular-level relationship between surfactant structure, foam stability, and performance-particularly in high-resilience (HR) foams under low volatile organic compound (VOC) constraints-remains poorly understood. This study explores the performance impact of three commercial, ultra-low VOC silicone surfactants (L-3002, l-3627, and l-3639) in HR PU foams across varying isocyanate indices (90 to 110) and surfactant concentrations. Using both free-rise and molded foam methods, we evaluated key properties such as foam settling, airflow, tensile and tear strength, rebound resilience, Hot ILD, Force-to-Crash, and Indentation Force Deflection. Surfactant l-3627 demonstrated the most consistent performance, offering superior foam stability, mechanical strength, and thermal resistance at 1.0 % loading. All surfactants performed optimally in polyol-rich conditions (index 90), but performance declined under isocyanate-rich conditions (index 110), indicating reduced surfactant mobility and stabilization. These insights support more precise surfactant selection to meet both regulatory and performance requirements. The SEM analysis revealed that higher surfactant concentrations promote more uniform and stable cell structures, contributing to increased compressive strength. However, in some cases, excessive surfactant levels-such as with l-3639-may lead to cell coalescence, negatively affecting the foam’s mechanical properties.