Regulating water content gradient in all-water-foamed polyurethane: synergistic structure–property optimization and water management mechanisms

Abstract

Developing polyurethane foams (PUF) with superior water absorption and retention remains challenging due to insufficient understanding of structure-–property relationships. This study systematically regulates the water content gradient (as blowing agent) in all-water-foamed PUF to optimize physicochemical properties. Comprehensive characterization via SEM, contact angle, water absorption, retention, and resilience tests reveals that water content critically governs microcellular architecture, surface hydrophilicity, and their synergistic effects on water management. The optimized formulation (2.5 phr water) achieves exceptional performance: 421.73% water absorption, 76.31% retention, and 55.10% resilience. These enhancements originate from uniform cell structures that harmonize hydrophilic group distribution with mechanical integrity. This work establishes fundamental guidelines for designing eco-friendly PU foams with balanced resilience and hydroscopic functionality, validated through theoretical and experimental insights.