Extraordinary aspects of bromo-functionalized multi-walled carbon nanotubes as initiator for polymerization of ionic liquid monomers

Abstract

Two ionic liquid monomers, 1-(2-acryloyloxy-ethyl)-3-methyl-imidazol-1-ium iodide (AMImI) and 1-(2-acryloyloxy-ethyl)-3-methyl-benzoimidazol-1-ium iodide (AMBImI), were synthesized and polymerized through atom transfer radical polymerization (ATRP). Poly(AMImI)-grafted multi-walled carbon nanotubes (denoted as MWCNT-poly(AMImI)) could also be fabricated through “grafting from” method of ATRP using bromo-functionalized MWCNT (denoted as MWCNT–Br) as initiator but MWCNT-poly(AMBImI) could not. Based on the thermogravimetric analysis and high resolution transmission electron microscopy, AMBImI monomer has encapsulated the MWCNT–Br probably through the π-π and cation-π interactions invalidating the initiation capability of MWCNT–Br. Besides, by mixing AMBImI with MWCNT–Br directly at room temperature, the MWCNT–Br was coated with a thin layer of AMBImI, whereas MWCNT–Br could not physisorb AMImI. Both MWCNT-poly(AMImI) and AMBImI-encapsulated MWCNT were dispersed well in 1-methyl-3-propylimidazolium iodide ionic liquid.