Removable Nonconjugated Polymers To Debundle and Disperse Carbon Nanotubes

In this study, we explore design rules for block copolymer (BCP)-based dispersants for carbon nanotubes (CNTs). We demonstrate the influence of polymer architecture on the dispersion, debundling, and stability of single-walled CNTs. These polymer dispersants based on pyrene-functionalized BCPs are tailored to perform multiple functions, namely, to (a) solubilize CNTs, (b) debundle CNTs, and (c) lift off CNTs following processing. BCPs were synthesized through an efficient ring-opening reaction of a poly 2-vinyl-4,4-dimethylazlactone (PVDMA) block. This chemistry provides greater flexibility to alter the polymer architecture, solubility, and degradability as well as to achieve a higher degree of incorporation of pyrene side groups. UV–vis–NIR absorption and photoluminescence emission studies indicate that a block-brush architecture consisting of polystyrene (PS) as the first block and mixed side chains of pyrene/PS or pyrene/polymethylmethacrylate grafted to the second PVDMA block gave the most stable CNT dispersions with high yields. Our studies show that a large number of pyrene side groups, as well as a large molecular weight solubilizing block, are required to disperse CNTs with a wide range of diameters from 0.7 to 1.7 nm. We further show that our design allows for thiol–thioester exchange chemistry to release the polymer wrappers from the CNT surface in an acid-free organic solvent medium. We envision this method to be generalizable for the dispersion of CNTs from small to large diameters.