The Preparation Of Boron Nitride Nanotubes Films By Ball Milling Method And Their Wettability

Boron nitride nanotubes(BNNTs) attract wide interest because of their unique structures along with super properties, such as outstanding mechanical properties and excellent thermal stability, all of which make them promising nanomaterials. Ball milling assisted with boron ink annealing method is an effective way to prepare BNNTs. During this procedure, B ink solution was printed onto the stainless steel substrates to obtain BNNT films with high quality with density. In this paper, we first optimized this method by exploring the most appropriate ball milling parameters, as well as processing the substrates for BNNTs growth.The lotus effect has been studied on BNNT films, their special hierarchical microand nano-structure on the rough surface could account for this. However, the petal effect with high adhesion has rarely been reported on BNNT films. Here, we disclose that BNNT films synthesized on stainless steel substrates by the as-mentioned method could present both a superhydrophobic state and a high adhesive force state under external force. The as-prepared BNNTs in the films have micro-sized length as well as nano-sized diameter. The combination of this micro- and nano-structure on the rough surface provides not only a sufficient roughness for superhydrophobicity, but also an adequate contact area for water droplets. We investigated different wetting states related to lotus effect and petal effect on BNNTs films, and the wettability model was also established to analysis the transition state. We believe a good understanding of the wettability of BNNT could further broaden its applications, and open up possibilities for fabricating superhydrophobic materials at micro-nanoscale with controllable wettability.In the flow field of direct methanol fuel cell(DMFC), superhydrophobic coatings on the micro channels of anode plates could effectively reduce the adhesion of water. This is beneficial for CO2 to be released, and enhance fuel efficiency. In this paper, we introduce a customizable local superhydrophobic micro channels by BNNT growth to satisfy the special requests in DMFC. Specially, the superhydrophobic BNNT films with high density and quality was controllable achieved on the side walls of flow channels by enhanced roughness as well as local B ink solution method, while the anode planes without BNNTs kept the original electrical properties. In addition, BNNT films with chemical inertness could also build up erosion resistant coatings for anode flow field.