Dispersion of carbon nanotubes in water by self-assembled micelles of branched amphiphilic multifunctional copolymers with photosensitivity and electroactivity†
Noncovalent surface modification has been proved to be one of the effective strategies for enhancing the properties of multi-walled carbon nanotubes (MWCNTs). When a non-covalent modification method is appropriately designed, novel opportunities for better performance of CNTs can be expected. In this paper, a novel kind of branched amphiphilic photo-sensitive and electro-active copolymer (BP(VCz/VM-alt-MA); BPVCM) was synthesized through a simple one-pot free radical copolymerization with 7-(4-vinylbenzyloxy)-4-methyl coumarin (VM), maleic anhydride (MA), 4-vinylbenzyl thiol (VBT) and 9-(4-vinylbenzyl)-9H-carbazole (VCz) as monomers. The copolymer BPVCM can self-assemble into homogeneous spherical micelles along the side-walls of MWCNTs and efficiently disperse MWCNTs in aqueous solution. In addition, the photosensitive coumarin groups of the copolymer chain undergo crosslinking under UV-irradiation, which leads to the encapsulation of MWCNTs in the crosslinked micelles and greatly improves the stability of the obtained MWCNT suspension. More interestingly, the electroactive carbazole moieties of the BPVCM–MWCNT composites could polymerize via an electrochemical polymerization method and form a MWCNT based conducting coating on the modified glassy carbon electrode (GCE), which eventually increases the number of electroactive sites and significantly accelerates the electron transfer. This novel preparation method permits us to obtain carbon nanotube hybrids exhibiting high water-dispersibility and stability while preserving their outstanding electrical properties, and would be valuable for construction of microelectronics and electrochemical sensors.