Intelligently Thermoresponsive Ionic Liquid toward Molecular Firefighting and Thermal Energy Management

Hydrocarbon-based phase change materials (PCMs) are accompanied by an inherent fire risk, which is hindering their further application especially in construction. Molecular-firefighting PCMs can be ideal and promising candidates to simultaneously ensure the highly efficient energy management and fire safety of PCMs. In this work, two novel phosphorus/nitrogen-containing ionic liquids ([DP][MI] and [DP][TEA]), composed of imidazole (MI) or triethylamine (TEA) cations and dicetyl phosphate (DP) anion, were synthesized for fire-proofing thermal energy management. The fire risk assessment confirmed that the extinguishing time of prepared [DP][MI] and [DP][TEA] was greatly shortened to 20 s and 3.5 min from 45 min for controlled sample, respectively. Moreover, the thermal enthalpy of [DP][MI] reached about 99.0 J g^-1. In addition, [DP][MI] and [DP][TEA] achieved low supercooling extents of 2.2 and 4.4 °C, separately. Both molecular firefighting and efficient energy management were achieved for [DP][MI] and [DP][TEA]. As applied in wood-plastic composite which is ubiquitous in construction, [DP][TEA] endowed the composite with temperature-regulating capability of about 10 °C in hut test and remarkably suppressed fire hazard of the composite, displaying a potential application value.