Polymer Journal

Kokado, Kenta; Chujo, Yoshiki

doi: 10.1038/pj.2010.13pmid: N/A

Polymer reactions of poly(p-phenylene–ethynylene) (PPE) based on the addition reaction of decaborane to the carbon–carbon triple bond were successfully carried out. The platform polymer was synthesized through Sonogashira–Hagihara coupling polymerization. The effective introduction of the boron cluster, and thus the subsequent formation of o-carborane, was supported by 1H and 11B nuclear magnetic resonance spectroscopies. The introduction rate of decaborane to the polymer main chain was proportional to the feed ratio of decaborane. Ultraviolet-visible absorption and photoluminescence studies illustrate the shortening of the effective π-conjugation length caused by the introduction of carborane clusters. Furthermore, the introduction of the boron cluster by the polymer reaction efficiently enhanced the heat resistance of PPE.

Matsuoka, Shin-ichi; Kikuno, Takashi; Takagi, Koji; Suzuki, Masato

doi: 10.1038/pj.2010.17pmid: N/A

Poly(ethylene glycol) with a molecular weight of 400 (PEG400) as an environmentally benign and highly viscous polymeric solvent was found to effectively accelerate the free radical polymerization (FRP) of methyl methacrylate and to afford a high-molecular-weight polymer. When the polymerization in PEG400 was performed at a monomer concentration of 3.0 mol l−1 and an initiator (2,2′-azobis(isobutyronitrile)) concentration of 0.3 × 10−2 mol l−1, the monomer conversion was completed for 6 h to afford a polymer with a number-average molecular weight (M n) of 838 000. After polymerization, the PEG400 solvent was readily recovered and reused. The solvent effects of highly viscous PEG400 were kinetically analyzed. The polymerization rate (R p) was proportional to the monomer concentration and the square root of both the initiator concentration and the viscosity of the polymerization media (η). For the FRP in the mixed solvents of PEG400 and toluene, both R p and M n values increased linearly with the square root of the η value. The kinetic study has shown that the highly viscous PEG400 solvent largely suppresses diffusion-controlled bimolecular termination.

Kimura, Kazuya; Gong, Jin; Kohama, Shin-ichiro; Yamazaki, Shinichi; Uchida, Tetsuya; Kimura, Kunio

doi: 10.1038/pj.2010.20pmid: N/A

Morphological control of poly(2,5-benzimidazole) (PBI) was examined by reaction-induced phase separation of oligomers during polymerization to prepare nanofibers. Three monomers, 3,4-diaminobenzoic acid (DABA), 3,4-diacetoamidebenzoic acid (DAcBA) and phenyl 3,4-diaminobenzoate (PDAB), were used to synthesize PBI. Polymerizations were carried out at 350 °C in a mixture of dibenzyltoluene isomers. Polymerization of DABA yielded spheres with plate-like crystals on their surface. Polymerization of DAcBA yielded almost no precipitates because of the high solubility of DAcBA oligomers. By contrast, polymerization of PDAB yielded aggregates of PBI nanofibers (of which the average diameter was ∼60 nm), which resembled nonwoven fabrics. These fibers were formed by precipitation of (2,5-benzimidazole) oligomers and their subsequent polymerization into a developing crystal structure. The structure of the monomer significantly influenced the morphology of the PBI product, and PDAB was preferable for the preparation of PBI nanofibers. The temperature of 10% N2 weight loss in these nanofibers was in the range of 634–644 °C and they were thermally stable.

Li, Hong; Qian, Chang-Ji; Sun, Li-Zhen; Luo, Meng-Bo

doi: 10.1038/pj.2010.9pmid: N/A

The conformational properties of a lattice self-avoiding polymer chain tethered to an interacting and impenetrable flat surface were simulated using a dynamic Monte Carlo method. The results show that the conformational size reaches a minimum at the critical adsorption point (CAP) and that the scaling behavior of the polymer at the CAP is the same as that in the bulk solution. The results provide a new method to determine the CAP of polymer chains.

Okada, Hiroshi; Matsumoto, Shuhei; Nakamura, Yo

doi: 10.1038/pj.2010.11pmid: N/A

Light-scattering measurements were taken on six samples of polystyrene (PS) with a benzyl group at one end of the chain (benzyl-PS) in toluene at 15 °C. The second and third virial coefficients (A 2 and A 3, respectively) were determined as functions of weight-average molecular weight, M w, which ranges from 6.0 × 102 to 1.2 × 104. It was found that values of A 2 for benzyl-PS were systematically smaller than those for PS with a butyl group at one end of the chain (butyl-PS) and that the difference becomes larger with decreasing M w. From the A 2 data obtained, the excess binary-cluster integral between the butyl end and the middle segments was estimated to be about three times larger than the binary-cluster integral between the benzyl end and the middle segments, where ‘excess’ means the difference from the binary-cluster integral between middle segments. The A 3 values for benzyl-PS for M w<104 were also smaller than those for butyl-PS. If we assume a term independent of molecular weight in A 3, the excess ternary-cluster integral among one butyl end and two middle segments was estimated to be about five times larger than that among one benzyl end and two middle segments.

Woo, Eamor M; Chou, Ying-Hsuan; Chiang, Wan-Jing; Chen, I-Tzu; Huang, I-Han; Kuo, Nai-Tzu

doi: 10.1038/pj.2010.18pmid: N/A

Two isomeric polyesters, poly(1,6-hexamethylene adipate) (PHA) and poly(ɛ-caprolactone) (PCL), were each blended with amorphous poly(vinyl methyl ether) (PVME) and investigated and compared in the crystalline and amorphous phases. The amorphous phase, T g, and crystalline morphology of the PVME/PHA blend were compared with those of classical PVME/PCL. Both blend systems exhibit a similar peculiar asymmetry with positive deviation in T g-composition relationships, and both are similarly miscible, with the PVME/PHA blend exhibiting χ 12=−0.21; for PVME/PCL, χ 12=−0.20. These values indicate that both blends are similarly miscible but have only quite weak interactions in the amorphous phase. Neat PHA shows a regime-I to -II transition, but neat PCL exhibits a regime-II to -III transition. On blending with PVME (at 20 wt%), both PVME/PCL and PVME/PHA blends undergo changes in crystallization temperature (T c). Dendritic spherulites in the high-T c (46 °C or above)-crystallized PVME/PHA blend assume a straight-stalk pattern (chrysanthemum flower pestles or banana stems). In contrast to the similarities in amorphous-phase miscibility, the crystalline phases of these two blends differ significantly. When crystallized at high T c (46 °C or above), the PVME/PCL (20/80) blend assumes a fluffy feather-like dendritic pattern, which is dramatically different from the straight-stalk dendrites in the PVME/PHA (20/80) blend.

Mekki, Sofiane; Saïdi-Besbes, Salima; Elaïssari, Abdelhamid; Valour, Jean-Pierre; Derdour, Aïcha

doi: 10.1038/pj.2010.8pmid: N/A

A series of anionic maleic surfactants were synthesized, and their chemical structures were characterized by NMR. The synthesized surfmers were then used in emulsion polymerization of styrene in the presence of potassium persulfate as an initiator. The polymerization kinetics were investigated, and the obtained latex particles were characterized in terms of particle size and size distribution. The results obtained were compared with the emulsion polymerization of styrene in the presence of an SDS surfactant. The influences of the nature and concentration of surfmers on polymerization conversion and particle size in particular were investigated and discussed.

Ito, Yoshihiko; Miyake, Toshiyuki; Suginome, Michinori; Katakura, Rie; Mitsuishi, Masaya; Miyashita, Tokuji

doi: 10.1038/pj.2010.14pmid: N/A

Optically pure, helical poly(quinoxaline-2,3-diyl)s (degree of polymerization, n=10–100), prepared by asymmetric living polymerization of 1,2-diisocyano-3,6-dimethyl-4,5-di(propoxymethyl)benzene with an optically pure organopalladium initiator, formed stable monolayers on a water surface. As the polymerization degree increased, more closely packed monolayers were formed, as indicated by surface pressure-area (π-A) isotherms. Up to 54 monolayers were deposited onto the solid support using the Langmuir–Blodgett (LB) technique. Polarized ultraviolet spectra of LB films showed that the helical axis was orientated parallel to the dipping direction. This optical property indicates that polymer molecules are organized anisotropically in LB films.

Oishi, Akihiro; Iida, Hiroshi; Taguchi, Yoichi

doi: 10.1038/pj.2010.16pmid: N/A

Copolymers of poly(butylene succinate) (PBS) with amino acids were produced from succinic acid (1), 1,4-butanediol (2) and 1 mol% of various amino acids. Their reaction time and molecular weight, as well as thermal and mechanical properties, were studied. The reaction time for polymerization was found to increase as the amount of amino acid was increased, except when L-aspartic acid (3) was used. The preparation of PBS copolymer including 3 was found to be quite different compared with the preparation of copolymer produced using amino acids. The thermal properties of copolymers including 3 are similar to those of the homopolymer without 3, yet the reaction time, molecular weight distribution and mechanical properties of the copolymers depend significantly on the amount of 3. The reaction time was found to decrease in proportion to the amount of 3. If 3 mol% of 3 is added to the polymerization process, the weight-average molecular weight was found to reach 247 000 in only 15 min. The molecular weight distribution (M w/M n) was found to increase and the break strain was found to decrease as the amount of 3 was increased. Similar effects due to the inclusion of 3 were observed in PBS copolymers including ɛ-caprolactone (4) or 3-octadecyloxy-1,2-propanediol (5).