In situ SEM nanomechanical single-tube pull-out measurement. (a) 2D testing schematic and (b) diameter distribution of the dispersed BNNTs measured by AFM (n = 550). (c) A BNNT-epoxy thin-film composite sample with protruding BNNTs (scale bar 500 nm), (d) HRTEM images of three protruding BNNTs (scale bars 10 nm), and (e) selected snapshots of one representative single-tube pull-out measurement (scale bars 200 nm).