Work

Flexible Polyurethane Foam with Durable Flame Retardancy and Mechanical Properties Based on Stable Hydrophobic Protection and Cross-Linking

Year: 2026

Type: article

Abstract: Flexible polyurethane foam (FPUF), with low crosslinking density and open-cell structure, is intrinsically hydrophilic and prone to structural collapse. This inherent vulnerability is exacerbated when incorporated with hydrophilic flame retardants like melamine (MEL), rendering FPUF vulnerable to water erosion and chemical attack, with rapid loss of both flame retardancy and mechanical integrity. To address these challenges, novel surfactant (F4) with both hydrophobicity and flame retardancy was prepared, which not only could be used as foam stabilizer in FPUF but also can be served as a durable hydrophobic shield to foam surface, owing to low-surface-energy of its fluorinated groups and hydrogen bonds formed by phosphorous in surfactant F4. Furthermore, blocked isocyanate (BI), as a post-crosslinker to enhance chemical crosslinking density so as to improve water resistance, effectively reinforcing FPUF structure while preserving its open-cell architecture. Therefore, with the combined effect of stable hydrophobic protection and enhanced chemical crosslinking, 1F4-30MEL-3BI-FPUF, with just 0.53 wt% of F4, demonstrates optimal comprehensive performance of flame retardancy (limiting oxygen index = 26.5%), hydrophobicity (water contact angle = 122.5o) and mechanical properties (compressive strength = 14.8 Kpa), as well as good absorption capability and well oil-water separation. Notably, these properties are well preserved after 24 hours of immersion in water, and even harsh conditions, such as strong acid, strong alkali, saturated NaCl and EtOH. This work presents a novel and straightforward strategy for fabricating high-performance FPUF with durable flame retardancy and structural stability especially under harsh conditions.

Source: ACS Applied Polymer Materials

DOI: 10.1021/acsapm.5c04589