Direct Polymerization of Highly Polar Acetylene Derivatives and Facile Fabrication of Nanoparticle-Decorated Carbon Nanotubes

Acetylenic monomers containing highly polar functional groups, especially those with active hydrogen atoms, have been difficult to polymerize because their toxic interactions with transition metal complexes deactivate catalyst systems. In this work, we succeeded in direct polymerizations of a series of highly polar phenylacetylene derivatives. The polymerizations of 4-ethynylbenzoic acid (1), 4-hydroxybutyl 4-ethynylbenzoate (2), 6-(4-ethynylphenoxy)hexanoic acid (3), 4-ethynylaniline (4), and 1-ethynyl-4-nitrobenzene (5) catalyzed by organorhodium complexes afforded corresponding polymers (P1−P5) of high molecular weight (Mw as high as 488 500) and low polydispersity index (Mw/Mn as low as 1.03). The structures of the polymers were characterized spectroscopically. Treatments by base and acid readily transformed neutral polymers P1 and P4 to polyelectrolytes P1− and P4+, respectively. Simple mixing of the conjugated polyelectrolytes with multiwalled carbon nanotubes (MWNTs) afforded polyacetylene/MWNT nanohybrids with water solubility of up to 316 mg/L. The hybrids were facilely decorated by metal (oxide) nanoparticles, furnishing multicomponent composites of P1−/MWNT/Ag, P4+/MWNT/Ag, and P4+/MWNT/ZnO.