Polymer Journal

Kamide, Kenji; Matsuda, Shigenobu

doi: 10.1295/polymj.16.591pmid: N/A

The effects of average molecular weight and molecular weight distribution MWD of the original polymer on the phase equilibrium of quasi-ternary systems consisting of multicomponent polymers, solvent 1 and solvent 2 were studied by computer experiments. For this purpose, polymers having strict monodispersity, Poisson (the weight-average molar volume ratio of the polymer to the solvents, X w=300), Schulz–Zimm (X w=150—6000, the ratio of the X w to number-average molar volume ratio of the polymer to the solvents, X w/X n=1.03—5.0), and Wesslau (X w=300, X w/X n=2.0—8.0) type molecular weight distributions were utilized. A small, but significant difference was observed for coexistence curves and other characteristic parameters between strictly monodisperse polymer and the Schulz–Zimm polymer (X w/X n=1.03). As X w of the original polymer, X w o, decreases, the partition coefficient σ, phase volume ratio R, and the polymer volume fraction in a polymer-rich phase v p(2) increases, and the MWD of the polymers in both phases becomes sharp. As X w/X n of the original polymer (X w o/X w o) decreases, σ, R, and v p(2) increase for a small relative amount of polymer in a polymer-rich phase ρp, but in larger ρp region, σ, R, and v p(2) decrease with X w o/X w o.

Fujiki, Michiya; Oikawa, Shigeru

doi: 10.1295/polymj.16.609pmid: N/A

An unusual temperature dependence of light scattering properties by pure polystyrene (PS) was observed in the temperature range of 30—170°C: the V′v and V v iso′ intensities minimized near T g, and the H′v intensity changed with measuring temperatures. These phenomena can be explained by “the scrambling effects of incident and scattered light” during transmission through the sample, as previously pointed out for PS glass by Claiborne and Crist. The PS 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 corrected V v iso intensity for PS glass was favorably compared with the values calculated from the thermal density fluctuation, indicating that PS glass was in a frozen state near T g. The corrected H v intensity for PS glass was nearly equal to the heretofore calculated value, assuming a randomly oriented anisotropic liquid for PS. Our experimental results showed no evidence for an ordered structure in pure PS glass, as is found in pure poly(methyl methacrylate) glass, but PS rubber has a partially oriented state.

Fukutomi, Takashi; Horikoshi, Toshio; Ishizu, Koji

doi: 10.1295/polymj.16.619pmid: N/A

The block copolymer composed of basic and acidic sequences, poly(N,N-dimethylaminopropylacrylamide-b-acrylic acid), was prepared by a mechanochemical method. Poly(N,N-dimethylaminopropylacrylamide) (PDAPA) was cleaved by ultrasonic irradiation in an aqueous solution of sodium acrylate. The block copolymer was separated as a precipitate from the reaction solution by controlling pH, and then fractionated by stepwise precipitations. The ratio, number of acidic monomer units/number of basic monomer units, was in the range of 0.3—145. The block copolymer showed microphase separation when it was cast from basic (NaOH aq.) or acidic (HCl aq.) solutions.

Ishihara, Kazuhiko; Kobayashi, Mineko; Ishimaru, Naoshi; Shinohara, Isao

doi: 10.1295/polymj.16.625pmid: N/A

To control the release of insulin in response to the concentration of glucose, a glucose–responsive polymer membrane was designed by combining a glucose oxidase (GOD) immobilized membrane, a sensor for glucose, with a poly(amine) membrane which regulates the permeation rate of insulin. The permeability of insulin was increased by the addition of glucose. Gluconic acid produced by an enzymatic reaction between GOD and glucose induced a decrease in the pH value of the medium. This caused the protonation of tertiary amino groups in the membrane resulting in an increase in the water content of the poly(amine) membrane. The permeability of insulin through a complex membrane thus increases with glucose concentration.

Tanisugi, Hideaki; Ohnuma, Hiroshi; Kotaka, Tadao

doi: 10.1295/polymj.16.633pmid: N/A

Swelling behavior was investigated on randomly-coupled (AB)n-type multiblock copolymers of bisphenol-A polycarbonate (PC) and polyoxyethylene (POE) in ethanol/water mixtures of various composition. The degree of swelling, Q w, defined as the weight ratio of the swollen and dry films, was dependent not only on PC/POE composition and block length but also on the sample’s history. As-cast specimens of the samples having 70 wt% POE content showed a high maximum in the Q w vs solvent composition curve at an ethanol content close to the azeotropic composition. This maximum disappeared by annealing and/or ethanol-conditioning the as-cast films. The swelling behavior of these conditioned films was similar to that of crosslinked POE gels. In the copolymers investigated, hydrophobic PC microdomains may act as physical crosslinks for the hydrophilic POE gel phase. Thus, as-cast specimens may have a large sorptive capacity because of imperfect microphase separation and a resulting loose quasi-network structure.

Tong, Zhen; Einaga, Yoshiyuki

doi: 10.1295/polymj.16.641pmid: N/A

The second virial coefficient A 2 for binary polystyrene mixtures F1 (10000)+F7 (74000) and F4 (43600)+F40 (491000) in cyclohexane was determined by light scattering in the temperature range from θ down near the cloud point. Here, the figures in the parentheses indicate the weight-average molecular weights of the component “monodisperse” samples. It was found that A 2 did not depend on either the molecular weights of the component polymers or the composition of the mixture but varied only with temperature.

Ishihara, Kazuhiko; Kobayashi, Mineko; Shinohara, Isao

doi: 10.1295/polymj.16.647pmid: N/A

Yoshikawa, Masakazu; Yokoi, Hideto; Sanui, Kohei; Ogata, Naoya; Shimidzu, Takeo

doi: 10.1295/polymj.16.653pmid: N/A

Inamura, Isamu; Toki, Kenzi; Tamae, Tsukasa; Araki, Takeo

doi: 10.1295/polymj.16.657pmid: N/A