Polymer Journal

Daoust, Hubert; St-Cyr, Daniel

doi: 10.1295/polymj.14.831pmid: N/A

The coil→helix transition in aqueous mixed solvents of alkaline metal salts of poly(L-glutamic acid) has been studied by circular dichroism (CD) as a function of solvent composition and time. Four organic solvents were used, dioxane, 2-chloroethanol (CE), 2,2,2-trifluoroethanol (TFE), and tetrahydrofuran (THF). CD spectra were taken just after the dissolution of the polypeptide, after three days and after seven days. In the water–dioxane pair, the transition is almost complete at the solubility limit of Li+ and Na+ salts (∼70% by weight of dioxane); for the K+, Rb+, and Cs+ salts, the helicity does not go over 20% even after seven days. When CE is used as organic solvent, the transition appears at a rather low CE content (25—35%) and is complete for all the salts. The transition occurs also for the salts up to their solubility limit in water–TFE but at high TFE content (∼80%). No transition takes place when THF is used as the organic solvent. A time dependent phenomenon in the helical content was found with dioxane and CE as organic solvents but none with TFE. The results are discussed in the light of the work of Morcellet and Loucheux.

Rokicki, Gabriel; Pawlicki, Jerzy; Kuran, Witold

doi: 10.1295/polymj.14.839pmid: N/A

A number of carbonates (RCH2)2CO3 (R=CH3, C2H5, CH2=CH, C3H7, C5H11, C6H5) have been synthesized by the reaction of alkali metal carbonates with corresponding halogen derivatives in the presence of activating agents such as crown ethers, polyglymes, polyamines, and triethylbenzylammonium chloride. The effects of various parameters (type of the halogen derivative, metal carbonate, activating agent, solvent and reaction time) on the reaction yield have been studied. The carbonates obtained were used as monomers in transesterification with diols and diphenols leading to the formation of polycarbonates. The polycarbonates obtained were characterized by means of IR spectroscopy and their intrinsic viscosity was determined.

Rokicki, Gabriel; Pogorzelska-Marciniak, Barbara; Kuran, Witold

doi: 10.1295/polymj.14.847pmid: N/A

Carbonate monomers, such as 1,4-bis(cyclohexyloxycarbonyloxylmethyl)-benzene and related compounds were synthesized from potassium cyclohexanolate, CO2, and α,ω-dibromo compounds in the presence of 18-crown-6 ether in aprotic solvents. Poly(p-xylylidene) was found to be formed in addition to the carbonate monomer when all the substances were simultaneously introduced into the reaction mixture. By an appropriate reaction method and conditions the formation of by-products was eliminated, thus permitting the main product 1,4-bis(cyclohexyloxycarbonyloxymethyl)benzene to be obtained in a yield higher than 90% with respect to the p-xylylene α,ω-dibromide introduced. The carbonate monomer thus obtained was then used in transesterification with diols or diphenols, and also in an ester exchange reaction to form the corresponding polycarbonates. The polycarbonates obtained were characterized and their reduced viscosity was determined.

Yoshida, Hirohisa; Nakamura, Kunio; Kobayashi, Yasuji

doi: 10.1295/polymj.14.855pmid: N/A

Enthalpy relaxation in polystyrene, poly(4-hydroxystyrene), and styrene/4-hydroxystyrene copolymers were studied by differential scanning calorimetry. It was found that the relaxation time strongly depends on the content of hydroxystyrene in the polymer. This phenomenon may be ascribed to the formation of hydrogen bonds between hydroxyl groups which act to restrict the segmental motion of the main chain. It was also found that the enthalpy relaxation of poly(4-hydroxystyrene) and hydroxystyrene-rich copolymers are promoted by the presence of a small amount of absorbed water.

Morishima, Yotaro; Tanaka, Tohru; Itoh, Yoshihiro; Nozakura, Shun-ichi

doi: 10.1295/polymj.14.861pmid: N/A

Amphiphilic random copolymers were prepared by radical copolymerization of 9-vinylphenanthrene (VPh) and N-(N′,N′-dimethylaminopropyl)methacrylamide followed by quaternization with dimethyl sulfate. The related monomer model compound was also synthesized by quaternization of N-(N′,N′-dimethylaminoethyl)-3-phenanthrylacetamide with dimethyl sulfate. The copolymers with VPh mole fraction (f Ph) up to about 0.47 were soluble in water. The fluorescence quenching of the copolymers in aqueous solution was compared with that of the model compound by using amphiphilic quenchers, N-methyl-N-(2-hydroxyethyl)aniline (MHEA) and N,N-di(2-hydroxyethyl)aniline (DHEA), and an anionic quencher, fumaric acid (FA). Hydrophobic association of MHEA and DHEA with the copolymers led to far more effective fluorescence quenching than the monomer model system. Electrostatic binding of FA with the copolymer also resulted in severe quenching of the fluorescence, while it was shown that a single charge on the monomer model is not sufficient to bind FA effectively to enhance the fluorescence quenching.

Oka, Yoshio; Koizumi, Naokazu

doi: 10.1295/polymj.14.869pmid: N/A

Impurity ions in poly(vinylidene fluoride) were successfully removed by electrodialysis in water and removal was confirmed by the reduction of dc conductivity. A comparison of electrical properties before and after electrodialysis showed the effects of the impurity ions. TSC and low-frequency dielectric measurement were made to study impurity ion effects on both stretched and unstretched samples. From the TSC study, the α relaxation in the crystalline α phase was found to give a clear peak following electrodialysis while the β relaxation in the amorphous phase was not affected. Also, impurity ions become mobile above 260 K and are responsible for the peak above the polarization temperature. From low-frequency dielectric measurements, similar results to those in TSC was obtained with respect to the a relaxation at 27°C. At 88°C, the ionic contribution to the increment of dielectric constants was pronounced and ionic polarization rather than ionic conduction was found to be dominant in the dielectric behavior in the frequency range of 0.01 to 10 Hz.

Watanabe, Masayoshi; Nagaoka, Katsuro; Kanba, Motoi; Shinohara, Isao

doi: 10.1295/polymj.14.877pmid: N/A

The electrical properties of certain polymeric solid electrolytes were studied. The polymeric solid electrolytes were prepared by dissolving several kinds of salts into the polycation matrix containing poly(propylene oxide) (PPO) or poly(tetramethylene oxide) (PTMO) segment in the main chain. The electrical conductivity at 20°C and the activation energy for conduction ranged from 10−7 to 10−10 S cm−1 and from 8 to 16 kcal mol−1, respectively, being dependent on the salt concentration, the salt species, the PPO segment size and the structure of the polyether segment. The ionic character of the electrical conductivity was demonstrated. Higher conductivity was observed with an increase in the salt concentration, in the PPO segment size and in the sum of the cation and anion radii of the salt in the PPO based polymeric solid electrolytes. The effects of the ion radius on conductivity were divided into two classes with respect to dependence on the salt species. These effects were due to the difference in the dissolving state of the salts in the PPO segment. The conductivity of the PTMO based polymeric solid electrolytes was lower than that of the PPO based polymeric solid electrolytes. The activation energy was mainly influenced by the salt concentration, and little influence of the salt species and the size and structure of the polyether segment was observed.

Tsukahara, Yasuhisa; Izumi, Atsushi; Hashimoto, Takeji; Kawai, Hiromichi

doi: 10.1295/polymj.14.887pmid: N/A

Polystyrene–poly(t-butyl acrylate) diblock polymers (PS–PTBA) were prepared by sequential anionic polymerization with s-butyllithium as the initiator and tetrahydrofuran at −78°C as the solvent. The microdomain structures of these polymers observed by electron microscopy were two coexisting microphases consisting of PS blocks and PTBA blocks. Linear dynamic mechanical responses of the block polymers exhibited two primary dispersions typical of two-phase polymer systems. Primary dispersions of PTBA microdomains and of PS microdomains shifted respectively toward higher and lower temperatures with increasing PTBA fraction. These shifting cannot be explained as the effect of molecular weight of the block chains i.e., the effect of the excess free volume of free chain ends. The shift of the PTBA primary dispersion was attributed to the excess free volume in the PTBA microdomains frozen-in during the solidification process and/or to the domain-boundary relaxation effect. The shift of the PS primary dispersion was considered to arise from domain-boundary relaxation effect, i.e., the effect of dynamical interactions of the chains in the respective domains at the domain-boundary interphase on mechanical relaxation behavior. The greater the specific surface area of the interfaces or the volume fraction of the interphase, the larger is the shift of PS and PTBA primary dispersions.

Se, Kazunori; Ohnuma, Hiroshi; Kotaka, Tadao

doi: 10.1295/polymj.14.895pmid: N/A

A diacetylene having 3-methyl-n-butoxy-carbonylmethyl-urethane (3BCMU) as a substituent was synthesized and exposed to 60Co-γ ray at various doses to obtain a polymer, poly3BCMU. The polymers obtained at low doses were of fairly high molecular weight and narrow distribution and those at high doses were of relatively low molecular weight and broad distribution. Changes in color of high and low-dose samples in CHCl3 and n-hexane were compared. The critical solvent compositions (CHCl3 content) at which yellow-to-blue or blue-to-yellow changes occurred were independent of polymer concentration but varied with molecular weight and temperature. Visible absorption spectra and Raman spectra were compared for yellow CHCl3 and blue CHCl3/n-hexane solutions of a high dose sample. Non-Newtonian intrinsic viscosities of these solutions were also compared. The results all suggested that poly3BCMU assumes a more extended, planar conformation in a poor solvent CHCl3/n-hexane than in a good solvent CHCl3, in contrast to flexible polymers in these solvents.

Nojima, Shuichi; Ohyama, Yutaka; Yamaguchi, Masashi; Nose, Takuhei

doi: 10.1295/polymj.14.907pmid: N/A

Spinodal decomposition in a critical mixture of polystyrene and poly-(methylphenylsiloxane) was studied by light scattering. The maximum intensity of scattered light, I m, and the corresponding wave number, k m, varied with the phase separation time t according to the following power–law relationships: I m∝t θ and k m∝t φ with θ=2.66 (±0.43) and φ=−0.90 (±0.20). These values of θ and φ were three times as large as those previously obtained for the off-critical mixtures. k m and t were reduced to scaled values by the correlation length and diffusion coefficient evaluated from static and dynamic light-scattering measurements in the homogeneous region. The plots of the scaled k m against the scaled t gave two composite curves corresponding to the critical and off-critical mixtures and were compared with typical theoretical predictions and experimental results for binary mixtures of small molecules and a polymer solution.