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Runaway silicone polymerisation enables innovative fire-shielding coatings
A novel intumescent silicone coating harnesses runaway hydrosilylation polymerisation to deliver exceptional thermal stability, flame resistance, and protective performance for fire-prone materials.
Intumescent flame-retardant (IFR) coatings are crucial for mitigating fire hazards, yet traditional systems often face challenges such as complex formulations, limited durability at high temperatures, and poor compatibility with substrates. A recent study introduces a groundbreaking IFR system based on runaway hydrosilylation polymerisation, leveraging tetravinylcyclotetrasiloxane (V4) and 1,3,5,7-tetramethylcyclotetrasiloxane (H4) to create polyH4V4. This novel polymer exhibits ultrahigh cross-linking density and thermal stability, addressing critical limitations of conventional flame-retardant coatings.
Upon thermal activation, the runaway polymerisation of polyH4V4 generates gases that enable instantaneous expansion into a porous, thermally stable coating. This mechanism provides superior heat shielding and substrate protection. The addition of vinyl-functionalised polymethylvinylsiloxane (PMVS) further enhances the coating’s performance, achieving a 3.7-fold height expansion compared to the pure polyH4V4 sample. Protected wood substrates demonstrated more than double the charring time under fire exposure, showcasing the coating’s effectiveness.
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Enhanced fire resistance with ceramicised silicone
In situ analyses, including XPS and TG-FTIR, revealed the flame-retardant mechanism of ceramicised polyH4V4, confirming SiOC conversion as the primary degradation pathway, leaving over 80 % residue at 800 °C. Hydrogen bonding with fumed silica and polysiloxanes provided precise rheology control, improving coating expansion and heat shielding. Despite its superior fire resistance, PMVS-modified variants showed limitations in SiO₂ dispersion, impacting spray application.
This scalable, innovative approach to IFR coatings paves the way for advanced fire protection solutions, particularly in urban infrastructure and high-risk environments, where thermal stability and rapid deployment are essential.
Source: Wang, D. et al., Harnessing silicone runaway polymerization for an instantaneous intumescent fire-shielding silicone coating. Progress in Organic Coatings, 213, 109940 (2025).
