Polymer Journal

Zhang, Linxi

doi: 10.1295/polymj.26.1201pmid: N/A

A modified FCM (Flory, Crescenzi, and Mark) model is developed to study the configurational statistics of poly(dimethylsiloxane) (PDMS) chain. In the model, the theoretical molar cyclization equilibrium constants Kx for small dimethylsiloxane ring are in agreement with the experimental data, and the theoretical characteristic ratio Cn=〈R 2〉/nl 2 and its temperature coefficient for long ring are close to the experimental results.

Takahashi, Yoshiaki; Kitade, Shinichi; Kurashima, Naoki; Noda, Ichiro

doi: 10.1295/polymj.26.1206pmid: N/A

Viscoelastic properties of binary blends of immiscible polymers with almost the same viscosity were studied under steady and transient shear flows in the light of the scaling relations in the constitutive equation of textured materials presented by Doi and Ohta. Samples used were blends of polydimethylsiloxane (PDMS) and polybutadiene (PB) with the composition ratios of 3:7, 1:1, 7:3, and 9:1 for PDMS:PB by weight. It was found that both shear stress σ12 and primary normal stress difference N 1 at steady state are proportional to shear rate γ̇ except N 1 of 9:1 blend, and the rescaled transient stresses after stepwise increase of shear rate compose a single line in terms of strains if the step ratios of shear rates are constant, in accordance with the scaling relations. For the 9:1 blend, in which the contribution of N 1 of component polymers cannot be neglected because the interface is small, however, the extra primary normal stress difference at steady state after subtracting N 1 of component polymers from the measured one was found to be proportional to γ̇ in accordance with the scaling relations.

Kitazawa, So; Hiraoki, Toshifumi; Hamada, Tatsuo; Tsutsumi, Akihiro

doi: 10.1295/polymj.26.1213pmid: N/A

In order to investigate side-chain dynamics of poly(γ-benzyl L-glutamate) in the solid state, 2H NMR spectra and spin-lattice relaxation-time T 1 of poly(γ-[κ-2H1]benzyl L-glutamate) and poly(γ-[ζ-2H2]benzyl L-glutamate) were measured over a wide temperature range. Line shapes for both samples below room temperature showed static-like axially symmetric powder patterns whose quadrupolar splittings are slightly smaller than the rigid lattice values, and decreased gradually with temperature. This suggests the presence of a rapid, small-amplitude librational motions at both of κ- and ζ-positions. T 1 analysis for such librational motion gave the correlation time of the order of 10−11—10−12 s. The spectral intensity started to decrease gradually from 208 K with an increase in temperature, and a remarkable intensity loss was observed at around 323 K. With a further increase in temperature, the spectrum recovered its intensity, and the motional averaged singlet-like spectra were observed for both samples, indicating the presence of rapid, large amplitude motions for the side chains. The T 1 minimum was observed at 383 K. T 1 and line shapes were fairly well simulated by use of the three-site jump model assuming a Gaussian and a log-Gaussian distributions for the angle between the C–2H bond and the C 3 axis and the jump rate, respectively. The average jump rates are located on the relaxation map reported for poly(γ-benzyl L-glutamate). The motional mechanism at higher temperatures follows the WLF type.

Cha, Yoon-Jong; Kim, Eung-Tai; Ahn, Tae-Kwang; Choe, Soonja

doi: 10.1295/polymj.26.1227pmid: N/A

Phase behavior in the blends of polyimide (PI; Matrimid 5218) which is a condensation product of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride and 5(6)-amino-1-(4-aminophenyl)-1,3,3′-trimethylidone and polyethersulfone [PES; poly(sulfone bis(p-phenyl) oxide)] has been investigated by differential scanning calorimetry (DSC), tensile test, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Miscibility was obtained from an optically transparent film and a composition dependent single glass transition temperature (T g) using DSC. Thermally induced phase diagram indicated LCST (lower critical solution temperature) type behavior. TGA measurement showed an increment in thermal stability and in weight retention in miscible blends. In mechanical measurement, the homogeneous 50/50 wt% blend showed the highest strain at break, yield stress and modulus, however these values were dramatically reduced after phase separation. Phase morphology was also observed by comparison to the domain growth in thermally induced phase separation using SEM and thereby this is a good agreement with the DSC and mechanical behavior.

Sugiura, Makoto; Minoda, Masahiko; Watanabe, Junji; Miyamoto, Takeaki

doi: 10.1295/polymj.26.1236pmid: N/A

Acylated derivatives of chitosan oligomers with a relatively high degree of polymerization (DP=4, 5, or 6) were synthesized and their mesophase properties were studied in comparison with those of the lower-DP homologues (DP=2 and 3) previously reported. By differential scanning calorimetry (DSC), all the compounds were found to show thermotropic mesomorphism in a temperature region below 150°C. The isotropization temperatures decreased with increasing DP, while the melting point remained at around 65°C, independent of DP. In addition to the narrowing of the mesomorphic region, the optical anisotropy as observed under a polarizing microscope remarkably decreased with increasing DP, indicating that the mesophase becomes less stable and ordered with an increase in DP. An X-ray diffraction analysis revealed that the tetramer as well as the dimer and trimer form a hexagonal ordered columnar phase (Dho), while the pentamer forms a disordered one (Dhd). On the other hand, the phase formed by the hexamer was not a columnar but a discotic nematic phase (ND). This is attributable to the highly anisotropic shape of the oligosaccharide core in the hexamer.

Hirasaki, Tomoko; Noda, Toshiaki; Nakano, Hiroo; Ishizaki, Yoshiaki; Manabe, Sei-ichi; Yamamoto, Naoki

doi: 10.1295/polymj.26.1244pmid: N/A

We intended to clarify the mechanism of virus removal in aqueous protein solution and human plasma solution through conventional and high performance regenerated cellulose hollow fiber (i.e., BMM and i-BMM). We employed Japanese encephalitis virus (JEV) as a typical virus. Two kinds of disperse gold particles (GP) with different size were represented as model particles of a virus and protein particles. We investigated the filtration characteristics concerning removability of GP and JEV (Φ g and Φ v, respectively) and the frequency distribution of GP and JEV within the walls of hollow fibers using a transmission electron microscope. The results were that (1) Φ g depended on the particle size, (2) the maximum population of captured GP moved to the outer wall with increase in challenge number, (3) i-BMM showed higher Φ g and Φ v than those of BMM. (4) Both Φ g and Φ v depend on the concentration of protein and total volume filtered. (5) The effects of coexistence of proteins on Φ g and Φ v are classified as initial change in the pore structure and local concentration of proteins in the pores (expressed as Φ g0) and subsequent change in the pore structure with filtration volume (φg0). These indicate that JEV and GP under the coexistence of protein are caught by BMM and i-BMM mainly through a sieving mechanism.

Oguni, Kazuma; Matsumoto, Akiko; Isokawa, Akira

doi: 10.1295/polymj.26.1257pmid: N/A

For investigating the mechanism of chiral recognition by cellulose derivatives, 13C NMR spectra of 1-phenylethanol were measured in CDCl3 in the presence or absence of cellulose tris(4-methylbenzoate) (1). (R)- and (S)-enantiomers of 1-phenylethanol showed different chemical shifts in the presence of 1. The degree of chemical shift difference was large at aromatic ipso carbon (1′-C) and methine carbon (1-C) with a hydroxyl group. Spin-lattice relaxation times (T 1s) were also measured to compare mobilities of the enantiomers. In the presence of 1, T 1 for each carbon of the (R)-enantiomer was shorter than that for corresponding carbon of the (S)-enantiomer. The presence of 1 restricts the mobility of the (R)-enantiomer more than that of the (S)-enantiomer. T 1 difference between (R)- and (S)-enantiomers was large at 1-C. The results indicate that 1-phenylethanol is chirally recognized by 1 at the point of 1-C carbon.

Sumi, Hiroshi; Haraguchi, Kenji; Inai, Yoshihito; Hirabayashi, Tadamichi; Yokota, Kenji

doi: 10.1295/polymj.26.1262pmid: N/A

The aldol condensation-type of group transfer polymerization (aldol-GTP) of E- and Z-isomers of 1-butadienyloxytrimethylsilane (BdTMS), 3-methyl-1-butadienyloxytrimethylsilane (MeBdTMS), and 3-phenyl-1-butadienyloxytrimethylsilane (PhBdTMS) was examined in the presence of p-anisaldehyde as an initiator and ZnBr2 as a catalyst. E-Isomers were rapidly polymerized to yield their polymers with a fairly narrow molecular weight distribution (M w /M n=1.2—1.3), while Z-isomers could not be at all E-BdTMS was treated with excess benzaldehyde in the presence of a small amount of ZnBr2 to yield an 1:1 aldol adduct. However, Z-BdTMS reacted slower than E-BdTMS under the same conditions. The different behavior between geometrical isomers suggests that propagation of aldol-GTP proceeds by way of a bicyclic transition state, in which only the E-isomer must be fit for stereochemical requirement.

Fomin, Sergel; Maciel, Alfredo; Ogawa, Takeshi

doi: 10.1295/polymj.26.1270pmid: N/A

The mechanical properties and their dependence on electron beam irradiation were studied for high molecular weight diacetylene-containing thermoplastics: poly(octa-3,5-diynylene sebactate) and poly(hexa-2,4-diynylene sebacate). The tensile strength of the polymers goes through a maximum reaching 330 MPa (with irradiation dose of 0.2 Mrad) for the former and 129 MPa (1 Mrad) for the latter in the case of oriented samples. Further irradiation of the samples leads to decrease in tensile strength, an increase in Young’s moduli and decrease in the strain at break. FT-IR spectroscopy of the samples showed that even at 15 Mrad, when tensile strength drops by several times, compared to unirradiated samples, irradiated samples still contain many unreacted diacetylenic groups. Data from thermal mechanical analysis showed that irradiation by 1 Mrad already leads to loss of the thermoplastic properties of material due to polydiacetylene network formation.

Akiyama, Eiichi; Takamura, Yuriko; Nagase, Yu

doi: 10.1295/polymj.26.1277pmid: N/A

Copolymerizations of the methacrylate-type monomers whose spacer consisted of only alkylene unit with the comonomers containing a disiloxane unit in the spacer component were carried out by radical polymerization. The effects of copolymer composition and structure of mesogen on the mesomorphic properties of the obtained copolymers were investigated, using DSC, optical polarizing microscope and X-ray diffractometry. T g and T i of the copolymers decreased with increase in comonomer component reflecting the flexibility of the siloxane linkage. The introduction of the comonomer containing a siloxane spacer and a laterally attached mesogen was effective to lower the temperature range of the mesophase. The copolymers, of which the comonomer content was about 50 mol%, exhibited an enantiotropic nematic phase, whereas the parent homopolymers exhibited a smectic phase. Consequently, the mesophase and temperature range of liquid crystalline state could be controlled by the introduction of a comonomer unit containing a siloxane spacer.