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Vinyl ethylene carbonate (VEC) derivatives bearing aromatic moieties were prepared by the catalyzed addition of carbon dioxide (CO 2 ) to butadiene monoxide (BMO) derivatives. The radical polymerization of the VEC monomers was carried out in bulk and solution by using a radical initiator, and those produced polymers were analyzed in detail by IR, NMR, and MALDI-TOF mass methods. These results indicated that radical polymerization of VEC derivatives proceeded through the selective vinyl fashion without depending on the substituents and solvents. Furthermore, the chain transfer reaction occurred easily in NMP and the produced polymer had the NMP moiety in the polymer terminal. The radical polymerization of the bifunctional monomer also proceeded through the vinyl fashion together with the chain transfer reaction in NMP and produced the gelation polymer. Electron-withdrawing of the substituents influenced the thermal property of the produced polymer and bifunctional polymer also obtained the high thermal stability than monofunctional polymer. In this report, the polymerization behavior and property of VEC derivatives bearing aromatic groups was summarized systematically.

The Rh-catalyzed polymerization of 2 - ethynylnaphthalene ( 2EN ) using ethanol or toluene solvents afforded helical poly(2 - ethynylnaphthalene)s (P2EN)s, i.e., yellow-colored P2EN( Y ) and red-colored P2EN( R ) in good yields, respectively. The diffuse reflective UV–vis (DRUV–vis) spectra of P2EN( Y ) and P2EN( R ) in the solid phase showed broad absorption peaks at 445 nm and 510 nm, respectively. These helical and its crystal structures were investigated using wide angle X-ray scattering (WAXS), resonance laser Raman, and molecular mechanics calculation using MMFF94 force field. Based on these analyses, we found that P2EN( Y ) was composed of stretched cis-transoid helices and P2EN( R ) was composed of contracted cis-cisoid helices in which form intramolecular π -stacking by ca. 3.4 A in distance between neighboring naphthyl rings. Furthermore, the contracted helix was energetically more stable than the stretched helix. The P2EN( Y ) changed to a red-colored polymer, P2EN( Y-R ), by immersion in toluene. This P2EN( Y-R ) completely coincides with the P2EN( R ) in its crystal structure and DRUV–vis spectrum.

Propargyl esters, HC CCH 2 OCOC n H 2n+1 ( 1 : n = 3, 2 : n = 5, 3 : n = 9, and 4 : n = 13), were polymerized using a [Rh(nbd)Cl] 2 catalyst and cocatalyst in an appropriate solvent at 0 °C and 40 °C. Number average molecular weights, M n of the resulting polymers, poly( 1 )–poly( 4 ), were 8000–54,000, and its dispersities ( M w / M n )s and the yields were estimated to be 1.6–3.6 and ca . ∼99%, respectively. These polymers were soluble in CHCl 3 , CH 2 Cl 2 , and THF, and insoluble in CH 3 OH and DMF. The amines, e.g., 2,6-dimethylpyridine and triethylamine worked well as the cocatalysts for the polymerization to give the yields, 93% and 88%, respectively. Further N , N- diethylaniline gave the maximum in cis %, 74%, although pyridine, aniline, pyrrole or imidazole did not work effectively. Remarkable line broadening phenomenon, LBP observed in the 1 H NMR spectra of poly( 1 ) and poly( 2 ) prepared at 0 °C or 40 °C, and poly( 3 ) prepared at 40 °C was correlated with the polymerization temperature and the radical concentration generated in the polymer. The LBP was interpreted by the dipole–dipole interaction between the protons in the polymer and unpaired electrons due to carbon radicals generated by the rotational scission of the cis C C bonds during the polymerization. Their UV–vis spectral shape of poly( 1 )–poly( 4 ) depended on the polymerization temperature and/or the alkyl chain length in the polymer. The XRD powder patterns of poly( 3 ) prepared at 0 °C, and poly( 4 )s prepared at 0 °C and 40 °C showed layer crystal structures with a slightly bent herringbone confirmed by molecular mechanics calculation. The λ max values of poly( 4 ) prepared at 40 °C in methanol showed 317 nm and 340 nm in the solution and on the alumina, respectively.

The poly(propargyl acetate) ( A ) having a helical cis – transoid structure was stereospecifically prepared using the Rh complex catalyst, [Rh(norbornadiene)Cl] 2 , in MeOH or NEt 3 solvent at 0 and 40 °C in moderate yield. Electron spin resonance (ESR) analysis of the polymer revealed the formation of the cis ( B ) and trans ( C ) radicals which were produced through the thermal rotational scission of the helical cis C C bonds in the main-chain during the polymerization. The spatial and geometrical structure was successfully deduced using the two analogues’ polymers in which either methyl or methylene group is deuterated, by the aide of computer simulation of the observed ESR spectra together with the calculation of spin density of the two radicals.