Three-dimensionally interconnected porous boron nitride foam derived from polymeric foams

Abstract

In this work, for the first time, we report the successful synthesis of three-dimensionally interconnected porous boron nitride foams (BNFs) with a high degree of crystallinity using porous sacrificial polymeric hard templates. Ammonia borane/CTAB solution were infiltrated inside highly porous preforms of poly(styrene-co-divinylbenzene) (PS), poly(acrylonitrile-co-divinylbenzene) (PAN) and poly(ethylhexyl acrylate-co-divinylbenzene) (PEHA) made using a high internal phase emulsion process. These were later subjected to pyrolysis under an ammonia atmosphere at the rather low temperature of 1150 °C for 90 minutes. The obtained products were characterized using X-ray diffraction, Fourier transformed infrared spectroscopy, N₂ sorption analysis, scanning electron microscopy, scanning transmission electron microscopy and high resolution transmission electron microscopy (HR-TEM). The synthesized BNFs closely replicated and retained the open-cellular interconnected microstructure of the polymeric templates. The HR-TEM results revealed the formation of highly crystalline BN stack layers in small domains. The prepared BNF using the PS template showed superhydrophobic behavior which was typical for all of the prepared samples, with a water contact angle of ∼144° and a high adsorption capacity of 1800% for used engine oil.