Phase structure engineering of nanostructural silicone-phenolic hybrids toward excellent ablation-resistance

Silicone-phenolic hybrids (SiPR) featuring unique self-ceramization abilities and excellent thermal-oxidative stabilities have attracted great interest as candidates for thermal protection in extreme environments. However, their applications are limited due to obvious phase separation, which leads to the early failure in the interface. To address these issues, a tailored silicone modified boron-phenolic hybrid (SBPR) is particularly prepared via adding Shiff base-containing organosilane (N-(triethoxysilylpropyl) salicylaldimine, ATSD), as the functional monomer, to a reaction mixture containing boron-phenolic resin (BPR) and triethoxymethylsilane (MTES). Accurate regulation of silicone-rich phase from nano-scale phase separation to molecular-scale homogeneity is achieved by fine tuning the hydrolysis condensation of silicone monomer. Profiting from the binary network with nano-scale phase size and ameliorated interface, optimized SBPR presents fascinating anti-ablation performance, the linear and mass ablation rates show reductions of 102.9 % and 17.02 % compared to those of the BPR counterparts. Moreover, a defined relationship of phase structures with fluorescence performances can be observed in SBPR, validated by the aggregation-induced emission (AIE) characteristics of ATSD. This work provides a promising platform for the phase-structure engineering of SiPR toward advanced thermal protection material designs and applications.