Molecular composites of a conducting polymer: syntheses and characterization of poly(1,4-phenylenevinylene)-crown ether rotaxanes

Abstract

Polyrotaxanes, a new class of polymer architectures, so called molecular composites, are comprised of macrocycles threaded by linear backbones with no covalent bond between them. By using poly(1,4-phenylenevinylene) (PPV), one of the most promising conductive polymers, as the linear backbone and different sizes of crown ethers (42C14, 60C20) as macrocycles, molecular composites of the conducting polymer were generated To compare with the PPV rotaxanes, PPV was synthesized and characterized by NMR, IR, UV-vis, photoluminescence spectroscopy, and TGA. The molecular weight of this polymer was measured by low angle laser light scattering. The poly(1,4-phenylenevinylene) rotaxanes were isolated by dialysis and solid-liquid extraction. They were also characterized by TGA, IR, UV-vis, photoluminescence spectroscopy, and solid state ¹³C NMR from which the mass contents of the crown ethers were calculated. The conductivities of the PPV rotaxanes were measured by the four-probe method. The conductivities of PPV42C14 rotaxane and PPV60C20 rotaxane were found to be 1.06x10⁻⁵ S/cm and 2.0x10⁻⁹ S/cm, respectively, after doping with concentrated sulfuric acid. The photoluminescence spectra of PPV rotaxanes showed different chemical shift and intensity from that of the PPV.