Self-Assembly and Visualization of Poly(3-hexyl-thiophene) Chain Alignment along Boron Nitride Nanotubes

Boron nitride nanotubes (BNNTs) were noncovalently functionalized with poly(3-hexyl-thiophene) (P3HT) to produce stable suspensions. The conjugated polymer and BNNTs interact via pi-pi stacking, and the resulting self-assembly of regiorandom P3HT on the BNNT surface is immediately evident through a color change and the appearance of a partially resolved absorption band. By employing polarized excitation fluorescence microscopy, we directly visualized the polymer-functionalized BNNTs and determined the conformation of the polymer on BNNT surfaces. Variation of fluorescence intensity with linear polarization direction showed conclusively that the P3HT chains were always aligned parallel to the BNNT long axis.