Polymer Journal

Fujiki, Michiya; Kaino, Toshikuni; Oikawa, Shigeru

doi: 10.1295/polymj.15.693pmid: N/A

The polarized and depolarized components of light scattering by pure poly-(methyl methacrylate) (PMMA) were measured as a function of temperature above and below T g. The PMMA sample used was prepared by a very careful procedure in which the evaporable monomer, initiator, and chain transfer agent were distilled in a closed vacuum system and in-situ polymerization was carried out above T g. The measured V v iso intensities were favorably compared with the values calculated from thermal density fluctuation in the temperature range from 20 to 140°C. The measured intrinsic H v intensity was fairly close to the value calculated assuming a randomly oriented anisotropic liquid for PMMA. Our experiment showed no evidence for an ordered structure in pure PMMA glass, as is found in pure polystyrene glass.

Hashimoto, Takeji; Tsukahara, Yasuhisa; Kawai, Hiromichi

doi: 10.1295/polymj.15.699pmid: N/A

The dynamic mechanical properties of “tapered” block polymers consisting of styrene and isoprene were studied in relation to the unique microdomain structure of these polymers. It was found from morphological observations that considerable mixing of the two monomers occurs in the primary structure, giving rise to a class of block polymers consisting approximately of “styrene-rich” and “isoprene-rich” block chains. Microphase-separated domain structures existed in the tapered block polymers prepared by sequential living anionic polymerization. Each domain, however, contained a substantial amount of dissimilar monomeric units, thus having an order-to-disorder transition temperature T c (the temperature at which the microdomains are dissolved into a homogeneous mixture) lower than that of the ideal block. This lowering in T c should have a substantial influence on flow behavior. The tapered block polymers gave essentially a single broad primary dispersion. This dispersion is related to the microbrownian motion of segments with a relaxation time between those of the parent homopolymers. The temperature dependence of the shift factor a T obeyed the WLF equation, in spite of the heterophase structure. The mechanical behavior was interpreted using a model in which two incompatible units undergo extensive mixing in each domain, leading to an increase in the interfacial volume fraction.

Tabuchi, Kenzo; Sakota, Naokazu

doi: 10.1295/polymj.15.713pmid: N/A

The photopolymerization of methyl methacrylate (MMA) with N-benzyl-pyridinium thiocyanate (BPT) was studied. The photopolymerization of MMA with BPT in dichloromethane gave an oligo(methyl methacrylate) (OMMA), which was presumably formed by initiation with thiocyano radical and termination with N-benzylpyridinyl radical. The photopolymerization was also accelerated by the addition of carbon tetrachloride, which captured effectively the pyridinyl radical as was also the case with N-benzylpyridinium bromide. Photopolymerization of MMA with N-benzylpyridinium chloride (BPC)–KSCN–CCl4 in an aqueous-organic two-phase was also examined. The results suggested the following BPC-recycling photo-initiation mechanism. BPT formed by the ion exchange reaction between BPC and KSCN in an aqueous layer photodecomposed to the SCN and N-benzylpyridinyl radical. The latter reacted with carbon tetrachloride to produce BPC and ·CCl3. Both ·SCN and ·CCl3 initiated the polymerization of MMA, and BPC was transferred to the aqueous layer. Photopolymerization in aqueous-organic two-phase was also remarkably accelerated in an emulsified system with sodium dodecyl sulfate or N-cetylpyridinium bromide, each of which increased the interface area between the aqueous and organic layers and facilitated the phase-transfer.

Hatada, Koichi; Kitayama, Tatsuki; Matsuo, Nobutaka; Yuki, Heimei

doi: 10.1295/polymj.15.719pmid: N/A

13C NMR spectra of isotactic-rich poly(alkyl vinyl ether)s were measured in toluene-d 8 at 110°C, with some improvements on peak separation. The 13C spin-lattice relaxation times (T 1’s) for syndiotactic sequences were consistently longer than those for isotactic ones, in contrast to the case of polypropylene and polymethacrylates, in which the T 1’s for isotactic sequences are longer than those for syndiotactic sequences. The nuclear Overhauser enhancement factors for the polymers of methyl and t-butyl vinyl ethers were close to the theoretical maximum. These results indicate higher flexibility of the syndiotactic sequences in poly(alkyl vinyl ether)s.

Shimidzu, Takeo; Yamana, Kazushige

doi: 10.1295/polymj.15.727pmid: N/A

5-Bromouridine oligonucleotides were synthesized directly from 5-bromouridine by a polycondensation method. The reaction of 5-bromouridine with tri(imidazol-1-yl)phosphine was carried out at a relatively low temperature and the subsequent in situ oxidation of the resulting phosphite oligomer was achieved with iodine and water. 5-Bromouridine oligonucleotides up to a hexamer were obtained in high yields. The phosphodiester linkage of the oligomer consists of both 3′,5′- and 2′,5′-linkages. The interaction of 5-bromouridine oligonucleotides with poly A was investigated.

Takahashi, Yasuhiro

doi: 10.1295/polymj.15.733pmid: N/A

In the crystal structure of poly(vinylidene fluoride) form II, four molecules with different orientation occupy a crystal site with different probabilities. The crystallite of form II gives two kinds of antiphase domain structures, one on the c-projection and the other on the a-projection. The structural change of form II by elongation and annealing temperature can be explained in terms of the antiphase domain structures and the long- and short-range order parameters. Drawing of the sample produces the domain walls and forms the antiphase domain structure in the crystallite during the recrystallization process. Increasing elongation temperature diminishes the fraction and domain size of the minor component of the antiphase domain structure on the c-projection. Annealing below 160°C hardly affects this structure. As the annealing temperature is increased above 166°C, the fraction of the minor component and domain sizes of both minor and major components on the c-projection become larger. The disorder on the a-projection diminishes with increasing annealing temperature. On the basis of the antiphase domain structure, a mechanism for the change in molecular packing accompanying the transformation from form II to form III is discussed.

Kawasaki, Tadayoshi; Komai, Takashi

doi: 10.1295/polymj.15.743pmid: N/A

O-Acyl-hydroxy-L-prolines containing acetyl, butyryl, hexanoyl, dodecanoyl, and benzoyl groups were synthesized and polymerized. Acylations took place in methanesulfonic acid with anhydrides and/or acyl chlorides. It was possible to obtain N-carboxylic acid anhydrides (NCA’s) by phosgene and subsequent silver oxide-charcoal treatment from these hydroxy-L-proline derivatives. These were polymerized in various solvent systems with triethylamine as the initiator. The intrinsic viscosity of these polymers in dichloroacetic acid was found to be 0.75 to 0.23. They were characterized by IR spectra, solubility in organic solvents and film forming ability. Introduction of various acyl groups to the poly(hydroxy-L-proline)s very strongly affected these physicochemical characteristics.

Kamachi, Mikiharu; Umetani, Hiroyuki; Kuwae, Yoko; Nozakura, Shun-ichi

doi: 10.1295/polymj.15.753pmid: N/A

An ESR study on the radical polymerization of diene compounds was carried out in frozen aromatic solvents, using benzoyl peroxide as a photoinitiator. The diene compounds were CH2 =CHX–CH=CHY (X=OCH3 and Y=COOCH2CH3, X=CH3 and Y=COOCH2CH3, X=H and Y=COOCH2CH3, and X=H and Y=OCOCH3). Spectra were observed at −120°C. The hyperfine splitting constants show that the propagating radical ends are allylic radicals whose unpaired electrons were completely delocalized over the three carbons of their chain ends. The conformation and spin density of the radical ends were estimated from the hyperfine splitting constants of methylene protons adjacent to the radicals and α-protons. The conformations could be explained by a single conformation. The reactivity of the propagating radicals was estimated from the propagation rate constants for radical polymerizations and reactivity ratios in the copolymeri-zations with styrene. The relation between the spin density and reactivity of the propagating radicals is discussed.

Xian, Chen Shang; Seki, Kazuhiko; Inokuchi, Hiroo; Ueno, Nobuo; Sugota, Kazuyuki

doi: 10.1295/polymj.15.763pmid: N/A

Kawasaki, Masaaki; Masuda, Toshio; Higashimura, Toshinobu

doi: 10.1295/polymj.15.767pmid: N/A