Dynamic thin film mediated slicing of boron nitride nanotubes†
A method has been developed to slice boron nitride nanotubes BNNTs under continuous flow in a vortex fluidic device (VFD), along with a method to partially purify the as received BNNT containing material. The latter involves heating the BNNTs to 600 °C followed by dispersing in a 1 : 3 isopropyl alcohol (IPA) and water mixture at 100 °C. The VFD mediated slicing of the BNNTs comprises irradiating the rapidly rotating glass tube (20 mm OD) with a pulsed Nd:YAG laser. Systematically exploring the operating parameter space of the VFD established slicing of ca. 200 μm long purified BNNTs down to 340 nm to 400 nm, in ca. 53% yield, in a 1 : 1 mixture of IPA and water, in the absence of reagents/harsh chemicals, at a flow rate of 0.45 mL min−1, a concentration of 0.1 mg mL−1 BNNTs and an 8.5k rpm rotational speed, with the pulsed laser operating at 1064 nm and 250 mJ per pulse.