Nitrogen-Coordinated borate esters induced entangled heterointerface toward multifunctional Silicone/Phenolic binary aerogel composites

Organosilicone/phsenolic hybrid resin (SiR/PR), which can withstand thermal oxidation, is constantly plagued by significant phase separation during the co-curing process. Herein, coordination interaction between borate esters and siloxane was firstly proposed to achieve domain size below the visible wavelength (20 nm) and homogenous SiR/PBA-PR aerogels. Profiting from the electron-deficient boron element, the weak interactions of matrixes was compensated by nitrogen coordinated borate esters during the rapidly grafting process. The entangled heterointerface inherently endows the integrated "organic-inorganic" hybrid aerogels with hierarchical alveolate structure after oxidative decomposition. As expected, the distributed organosilicone, stabilized by nitrogen coordinated borate esters, shields the organic and carbonaceous components from ubiquitous oxygen-rich heat flow, thereby qualifying the SiR/PBA-PR aerogels with great thermal oxidation stability (R1000, Air > 50 wt%) and specific compressive strength (1400 N & sdot;m/kg). Besides, owing to the inherited heterointerface after pyrolysis, SET of pyrolytic sample with 50 % SiR even increase slightly (2.5 %) compared with the reduction of 73 % in SET of that without SiR after flame ablation. This strategy of silicone resin doping in nitrogencoordinated phenolic resin will pave a way for "organic-inorganic" hybrid materials.