Synthesis and characterization of polyfunctional diacetylenes
The dimer, trimer, and tetramer of 1,11-dodecadiyne were synthesized. Sufficient proof of the syntheses is presented to clear up uncertainty in the work previously reported by other researchers. The solid state polymerization of the dimer was investigated by infra-red spectroscopy, X-ray diffraction, and electron diffraction analysis. The dimer was found to have polymorphs. The melt-crystallized polymorph had higher polymerizability than the solution-crystallized one. IR bands due to the diacetylene moiety were clearly identified through the comparison of the IR spectra of the dimer, trimer, and tetramer. The unit cell dimensions of both the polymorphs were not consistent with the previously reported structure in which both the diacetylene and terminal acetylene groups are polymerized to form an inherently electrically conducting polymer. The discrepancies in the previously reported synthesis, X-ray diffraction, and electron diffraction analysis are critically pointed out. It was concluded that all the previously reported synthesis and structures are wrong. The polymerization of the terminal acetylene group was concluded not to take place in the solid state. The unit cell dimensions and space group of the polymer from the melt-crystallized dimer were determined by electron diffraction analysis in which the three dimensional reciprocal lattice was constructe d from the diffraction patterns obtained by sequential tilting of the sample to the electron beam in the electron microscope. The unit cell was monoclinic, space group P21/n. The thermochromic behavior of the polymorphs were related to the crystalline phase change using X-ray powder diffraction analysis. Amphiphilic diacetylenes of the type HCequivC-(CH2) n-CequivC-CequivC-(CH2)8-COOH (n = 6 and 12) were synthesized. The solid state polymerization of the bulk crystals, monolayers on the gas-water interface, and multilayers was investigated. The diacetylene moieties underwent polymerization upon irradiation by UV or ?-rays. The polymerization of the terminal acetylene groups was not observed. Enhanced polymerizability and stability of the monolayers on subphases containing LiOH are explained by a proposed model of the monolayers.
School:Case Western Reserve University
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:synthesis characterization polyfunctional diacetylenes
Date of Publication:01/01/1992