The cationic polymerization of glycidyl phenyl ether (GPE) was examined with novel phosphonic acid esters, O,O-di-p-methylbenzyl phenylphosphonate (1a), O,O-dibenzyl phenylphosphonate (1b), and O,O-di-p-nitrobenzyl phenylphosphonate (1c), as initiators. GPE did not convert with 1a−c even at 210 °C in the absence of ZnCl2. In the presence of ZnCl2 along with phosphonic acid esters 1a, 1b, and 1c, the polymerization of GPE did not proceed below 90, 130, and 170 °C, respectively, but it rapidly proceeded to afford polyGPE with Mn of 2500−5000 above those temperatures. It was found that 1a, 1b, and 1c served as thermally latent initiators in the polymerization of GPE in the presence of ZnCl2. Electron-donating substituents on the benzyl group of the phosphonic acid esters increased the initiator activity. The initiation species was identified as a benzyl cation by 13C-labeled experiments.
This article deals with design and synthesis of functional polymers having amino acid moieties in the main and side chains. The first half overviews peptides, polyamides, polyesters, polyurethanes, polysulfides, along with dendrimers consisting of amino acid repeating units in the polymer main chain synthesized by ring-opening polymerization, polycondensation, and polyaddition. The second half overviews polymers having amino acid and peptide moieties in the side chain mainly synthesized by radical polymerization of the corresponding vinyl monomers, some of which show unique properties concerning specific rotation, solubility, glass transition behavior, higher order structure, and drug-releasing function.
Cationic ring-opening polymerization of a cyclic carbonate carrying an exomethylene moiety, 5-methylene-1,3-dioxan-2-one (ExTMC), was carried out, and its behavior was compared with a cyclic carbonate having no exomethylene group, 1,3-dioxan-2-one (TMC). ExTMC afforded the polymers with larger molecular weights than TMC under any conditions. The observed molecular weights of the polymers agreed well with the calculated ones in the polymerization of ExTMC with TfOH at 0 °C. A linear relationship was observed between the conversion and number-average molecular weight of the polymer obtained in the polymerization of ExTMC, which could not be observed in the polymerization of TMC. After ExTMC was completely converted, the polymerization took place again when the same amount of ExTMC was introduced into the polymerization mixture. The effect of the exomethylene group on the polymerization behavior was analyzed by an ab initio molecular orbital calculation to determine the possibility of the presence of an allylic cationic intermediate. It was suggested that the stabilization of the propagating cation by the exomethylene group caused the living character of the cationic polymerization of ExTMC. Furthermore, a block copolymer of ExTMC with a vinyl ether was synthesized as an application of the pseudo-living polymerization of ExTMC.
Star-shaped polymers have attracted attention due to their unique solution properties and viscosities. These effects are attributed to their hydrodynamic radii that differ significantly from those of linear polymers. The present study reports the synthesis of star-shaped helical polyacetylenes substituted with l-valine- and l-threonine-based optically active groups. The formation of star-shaped polymers was confirmed by size exclusion chromatography, solution viscosity, dynamic light scattering, and small-angle X-ray scattering measurements. The chiroptical intensities of the star-shaped polymers tended to be smaller than those of the corresponding linear polymers in solution but larger in the film state. The water contact angles and refractive indices of the star-shaped polymers were smaller than those of the linear polymers.
