| 초록 |
The introduction of functional substituents into polyacetylene causes a drastic change in various properties of the polymers, because of their solubility, fusibility, and interesting chemical, optical, and other properties. The polymerization of 2-propynyl-tetra-O-β-glucopyranoside was performed by various transition metal catalysts. We firstly test the polymerization behaviors of 2-propynyl-tetra-O-β-glucopyranoside by Pd, Pt, Ru-chlorides. PdCl2 was found to be effective for this polymerization to give the corresponding polymer in 52 % yield although the monomer carry the highly bulky substituents. PtCl2 and RuCl3 showed similar catalytic activity with PdCl2. (NBD)PdCl2, which showed good solubility in the polymerization solvents, was also used. However, the polymer yield was somewhat low (32%). Rhodium dimer catalyst, [Rh(NBD)Cl]2, also polymerize the 2-propynyl-tetra-O-β-glucopyranoside to yield the corresponding polymer in 42% yield. The above polymerizations proceeded mostly in mild manner. W- and Mo-based catalysts were also used for the polymerization of 2-propynyl-tetra-O-β-glucopyranoside. Mo-based catalysts including MoCl5, MoCl4, MoCl5-EtAlCl2, MoCl5-Ph4Sn were effective for the polymerization (polymer yield: 28 %, 25%, 35%, and 30%, respectively). On the other hand, W-based catalysts such as WCl6 alone and WCl6-EtAlCl2 failed to polymerize the present monomer to give only a trace amount of oligomeric product. The chemical structure of poly(2-propynyl-tetra-O-β-glucopyranoside) were characterized by various instrumental methods such as IR, NMR, UV-visible spectroscopies. The FT-IR spectrum of the polymer did not show the acetylenic carbon-carbon bond stretching (2121 cm-1) and acetylenic C-H bond stretching (3276 cm-1) frequencies of the monomer. Instead, the C=C stretching frequency peak of conjugated polymer backbone at 1570-1680 cm-1 became more intense than that of the monomer. The characteristic peaks of carbonyl and ether functional groups were observed at 1756 and 1227 cm-1, respectively. In 1H-NMR spectrum of polymer, the aliphatic protons were observed broadly at 2.0, 3.3, 4.0, 4.9, and 5.2 ppm. In the 13C-NMR spectrum of poly(2-propynyl-tetra-O-β-glucopyranoside), the carbon peaks on the conjugated polymer backbone were observed at the region of 130-140 ppm. The aliphatic carbon peaks were also observed at 20.3, 61.6, 68.1, 70.6, and 71.8 ppm. In the UV-visible spectra, the absorptions at long wavelength (up to 700 nm) due to the π→ π* interband transition of the conjugated polymer systems were observed. From these spectral data, we concluded that the present polymer have the conjugated polymer backbone system with the designed substituents. This polymer was soluble in such solvents as chlorofrm, chlorobenzene, toluene, and DMSO, but insoluble in methanol, ethyl ether, hexane, etc. The number-average molecular weights were in range of 6,520-12,500. The TGA thermogram exhibited that the polymer is stable up to 180 oC. The morphology of the polymers was also investigated by X-ray diffraction analysis. Because the peaks in the diffraction pattern were broad and the ratio of the half-height width to diffraction angle is greater than 0.35, the present polymers were mostly amorphous. In order to measure the electrical conductivity, the doping experiment was performed by the exposing the polymer pellet to the iodine vapor. The doping (charge-transfer complex formation) ability of the present polymer was found to be low (the mole ratio of doped iodine to the monomeric repeating unit: 0.12-0.15), which was very similar with those of the conjugated polymers from the monomers with bulky substituents. The electrical conductivities of the iodine-doped polymers were in the range of 7.4 x 10-4 – 2.0 x 10-3 S/cm. |
