High-performance flexible polyurethane from renewable castor oil: Preparation, properties and mechanism

• Multifunctional green fire-retardancy adsorbent CPK was synthesized. • Green intrinsic flame-retardant foam achieved eminent smoke suppression effect. • Modified samples also had better lipophilic adsorption properties. • Low-valent phosphorus mainly exerted fire-retardancy effect in gaseous phase. Bio-based flexible polyurethane (PU) with fire-retardancy can not only relieve the pressure of limited fossil resources, but also effectively solve the serious problem derived from fire accident. Herein, diphenylphosphinyl chloride and 3-aminopropyltriethoxysilane (KH550) were introduced into the castor oil molecular chain, and modified castor oil (CPK) was successfully synthesized. By using CPK to replace part of the original polyol, we had prepared flexible PU: The PU/CPK 15.0 mol% sample successfully passed the vertical combustion test and achieved the eminent flame-retardant and smoke-suppressing effect. In the rapid adsorption test of organic solvents, both toluene and n-hexane can be quickly and completely absorbed by the modified foam sample, while the unmodified foam was not good as that. Besides, the modified foam also met certain mechanical properties. This work broadens the thinking for the preparation of high-performance flexible PU materials with green intrinsic fire-retardancy.