In Situ Nitroxide Mediated Polymerized Poly(Acrylic Acid) as a stabilizer/compatibilizer Carbon Nanotube/Polymer Composites
Résumé
Carbon nanotube (CNT) polymer composites were synthesized via in situ nitroxide-mediated diblock copolymerization.
Poly(acrylic acid) (PAA) was chosen as a first block to obtain a precomposite CNT-PAA which is readily dispersible in various
solvents including water. The immobilization of the stable poly(acrylic acid) alkoxyamine functionality on the nanotube surface
occurs during the synthesis of the first block without CNT prior treatment. The living character of this block is established by
spectroscopic methods and the nature of the CNT/PAA interaction is discussed. This living first block offers the opportunity to
reinitiate the polymerization of a second block that can be chosen among a wide range of monomers. This versatility is illustrated
with a second block containing methyl acrylate (MA) or styrene (S). Scanning and transmission electron microscopies confirm
good CNT dispersion in the polymer network, while transmission electron microscopy also spots the anchorage locations of PAA
on the CNT surface. Such nanotubes wrapped by diblock copolymers can be dispersed in various polymer matrices to create
CNT—polymer composites. Conductivity measurements show that these composites obey a percolation-like power law with a low percolation threshold (less than 0.5 vol%) and a high maximum conductivity (up to 1.5 S/cm at room temperature).