Showing papers in "Polymer Journal in 1984"

Glucose Induced Permeation Control of Insulin through a Complex Membrane Consisting of Immobilized Glucose Oxidase and a Poly(amine)

Abstract: 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.

Study on the solubility of cellulose in aqueous alkali solution by deuteration IR and 13C NMR.

Abstract: Study on the Solubility of Cellulose in Aqueous Alkali Solution by Deuteration IR and 13 C NMR

Double-stranded Helix of xanthan in dilute solution: evidence from light scattering

Abstract: A sample of xanthan, a bacterial β-1,4-D-glucan with ionic side chains, and its sonicated fragments in 0.1 M aqueous NaCl and cadoxen at 25°C were studied by light scattering. Radii of gyration ‹S2›1/2 as a function of weight-average molecular weight Mw in these two solvents, combined with the values of about 2 for the ratio Mw (in 0.1 M NaCl)/Mw (in cadoxen), showed that xanthan dissolves as rodlike dimers in 0.1 M aqueous NaCl and as single flexible chains in cadoxen. The contour length per main chain glucose residue of the xanthan dimer was found to be 0.47±0.01 nm, which agreed with the pitch (per glucose residue) of the 51 double-stranded helix proposed for the crystalline structure of xanthan. Thus, it was concluded that the xanthan dimer in 0.1 M aqueous NaCl has the 51 double-stranded helical structure.

Double-stranded helix of xanthan in dilute solution: Further evidence

Abstract: Viscosity measurements were made on ten samples of a bacterial polysaccharide xanthan in 0.1 M aqueous NaCl and cadoxen (at 25°C); the polymer dissolves as dimers in the former and as monomers in the latter. Intrinsic viscosities [η] as a function of molecular weight in 0.1 M aqueous NaCl fitted to Yamakawa–Yoshizaki’s theory for the Kratky–Porod wormlike chain with a linear mass density ML of 1940 nm−1, a persistence length of 120 nm, and a chain diameter of 2.0—2.5 nm. This ML corresponds to the 0.47 nm pitch (per main chain glucose residue) of the 51 double-stranded helix proposed for the crystalline structure of xanthan, and is consistent with the previous conclusion from light scattering that the xanthan dimer in 0.1 M aqueous NaCl has this helical structure. On the other hand, the values of [η] in cadoxen showed that the single chain of xanthan in this solvent is essentially flexible. Those in mixtures of cadoxen and water decreased sharply with an increase in cadoxen composition in a range from 60 to 70wt% cadoxen. The double-helical xanthan dimer was not restored once dissociated into single chains in pure cadoxen at 25°C or in pure water at 95°C.

Piezoelectricity in Polyacrylonitrile.

Abstract: The piezoelectric and related properties in ion-doped (NH4NO3, NaNO3) and undoped films of polyacrylonitrile have been measured as a function of temperature. The piezoelectric constants of both ion-doped and undoped films reach a maximum around 80°C and thereafter decrease markedly with temperature. At about this same temperature, a maximum of thermally stimulated discharge current (TSDC) is also observed with both ion-doped and undoped films. These two effects are thought to have a common origin: the randomization of nitrile dipoles in ordered regions. The piezoelectric constant of pre-stretched films is higher than that for unstretched polyacrylonitrile.

Living Radical Polymerization of Methyl Methacrylate with a Tetrafunctional Photoiniferter: Synthesis of a Star Polymer

Abstract: Living Radical Polymerization of Methyl Methacrylate with a Tetrafunctional Photoiniferter: Synthesis of a Star Polymer

Thermodynamics of Polymer–Polymer–Solvent and Block Copolymer–Solvent Systems I. Experimental Measurements

Abstract: A new multiple-celi apparatus for vapor-liquid equilibria measurements in concentrated polymer solutions is described. Experimental data on vapor-pressure lowering for four polymer–polymer–solvent systems and one block copolymer–solvent system are reported. The Flory–Huggins χ interaction parameters for the corresponding polymer pairs are evaluated. For ternary systems, the results are expressed in terms of a parameter χ1,23 which reduces to the classical Flory–Huggins χ interaction parameter for the case of binary mixtures. Experimental data measured in this work are compared with existing literature data.

Identification of Branches in Low-Density Polyethylenes by Fourier Transform Infrared Spectroscopy

Abstract: Qualitative and quantitative analysis of short chain branches was carried out on a series of low-density polyethylenes by Fourier transform infrared spectroscopy. The peak position of the methyl symmetrical deformation bands around 1378 cm−1 was found to vary with the type of branches and used for identification of the branch type in low-density polyethylenes. The reciprocals of extinction coefficients of the methyl deformation bands were determined for various branch types on the basis of 13C NMR data. The values changed from 0.39 to 0.76 depending on the type of branch. The methyl rocking bands ranging from 880 to 940 cm−1 were examined using brominated samples. The peak positions also depended on the type of branch. For the methylene rocking bands, the peak at 772.2 cm−1 due to the ethyl branch was clearly observed, but that due to the n-butyl branch was not detected around 745 cm−1, indicating the n-butyl absorption to be located very close to 730 cm−1 rather than 745 cm−1.

Temperature dependence of ionic conductivity of crosslinked poly(propylene oxide) films dissolving lithium salts and their interfacial charge transfer resistance in contact with lithium electrodes

Abstract: Temperature Dependence of Ionic Conductivity of Crosslinked Poly(propylene oxide) Films Dissolving Lithium Salts and Their Interfacial Charge Transfer Resistance in Contact with Lithium Electrodes

Immobilization of synthetic bilayer membranes as multilayered polymer films

Abstract: Film a trois couches (composite bicouche d'alcool polyvinylique en sandwich entre deux couches d'acetate de cellulose)

Multi-Phase Equilibrium in Aqueous Solutions of the Triple-Helical Polysaccharide, Schizophyllan

Abstract: Ternary phase diagrams were determined at 25°C for aqueous solutions of a rodlike polysaccharide schizophyllan, using three fractionated samples of different axial ratios x: sample T-3, x=223; sample UR-28, 36.8; sample U-110, 18.3. Two ternary systems UR-28+T-3+water and U-110+T-3+water were investigated. The phase diagram of either system was occupied by a wide biphasic region, where a dilute isotropic phase and concentrated cholesteric phase coexisted at equilibrium. The phase diagram of the system U-110+T-3+water contained two additional regions, one where two cholesteric phases and one isotropic phase coexisted at equilibrium and the other where two cholesteric phases coexisted. A remarkable molecular weight fractionation took place on phase separation, and the larger x component was almost excluded from the dilute phase (or phases). All these features of the phase diagrams were consistent with the theoretical prediction by Abe and Flory for athermal ternary solutions. Quantitative agreement between theory and experiment was far from satisfactory, although the disagreement was considerably diminished when the interaction parameter was incorporated into the Abe–Flory theory.

Ultra-high modulus and strength films of high molecular weight polypropylene obtained by drawing of single crystal mats.

Abstract: Ultra-High Modulus and Strength Films of High Molecular Weight Polypropylene Obtained by Drawing of Single Crystal Mats

Insulin Permeation through Amphiphilic Polymer Membranes Having 2-Hydroxyethyl Methacrylate Moiety

Abstract: Insulin Permeation through Amphiphilic Polymer Membranes Having 2-Hydroxyethyl Methacrylate Moiety

Gas permeation through polymer/liquid crystal composite membrane

Abstract: Gas permeation was investigated for a polycarbonate (PC)/N-(4-ethoxy-benzylidene)-4′-butylaniline (EBBA) (=40/60 in wt%) composite membrane on the basis of its surface and internal structures. Scanning electron microscopic observations for the matrix polymer after extraction of EBBA with hot ethanol showed that EBBA molecules form a continuous phase in the three-dimensional network of PC fibrils. On the basis of sorption and sorption-desorption experiments the composite membrane could be regarded as a homogeneous medium in the range above the crystal-nematic phase transition temperature TKN. The permeability coefficients P for hydrocarbon gases in the composite membrane above TKN increased discontinuously 100—200 times as much as those below TKN over several degrees in the TKN range. P for hydrocarbon gases below TKN decreased with an increase in the number of carbon atoms, while those above TKN showed the opposite trend with an increase in the number of carbon atoms. These facts clearly indicated that permeation is predominantly controlled by diffusion below TKN and significantly by solubility above TKN.

Density Fluctuation in Amorphous Polymers by Small Angle X-Ray Scattering

Abstract: Density fluctuations in an infinite volume can be obtained by extrapolating the scattering intensity to the zero scattering angle, while those in a finite volume having a radius of several tens of Angstrom can be obtained from intensities at non-zero scattering angles. Small angle X-ray scattering intensities for condensed phases were approximated by I(s)=I(0)exp(As2). This s dependence of the intensity arises from the repulsive interaction between two particles. Since the density fluctuations in the above two types of volume (infinite and finite) were nearly the same in magnitude and temperature dependence for an amorphous polymer (PMMA), it was concluded that no density fluctuations due to structural inhomogeneity exist. The temperature dependence of the density fluctuations in a finite volume for PMMA and PC exhibited a second transition temperature T* below Tg, the glass transition temperature.

Vinyl ether oligomers with conjugated-polyene and acetal terminals: A new chain-transfer mechanism for cationic polymerization of vinyl ethers.

Abstract: Cationic oligomerizations of isobutyl vinyl ether (IBVE) and 2-chloroethyl vinyl ether (CEVE) were carried out with various initiators (BF3OEt2, I2, CF3SO3H, CH3SO3H, and CH3COClO4) in benzene at 70°C, and the structure and molecular weight distribution of the products were investigated. The oligomers obtained were constituted of oligo(vinyl ether)s with a conjugated polyene (I) or an acetal (II) terminal. To account for the formation of I and II, a new chain-transfer mechanism has been proposed, which involves successive dealcoholation from the growing chain to give polyene I and a reaction of the released alcohol with the growing vinyl ether cation to yield acetal-capped oligomers II. Oxo acid initiators (CH3SO3H, CF3SO3H, and CH3COClO4) induced the dealcoholation more than BF3OEt2 or iodine, giving higher yields of I. It was also demonstrated that the polyene and acetal terminal are formed not only in the oligomerization at high temperatures but also in the polymerization at around 0°C. Thus the coloration of reaction mixtures in vinyl ether polymerization has now been interpreted by the formation of polyenes I.

Characterization of the microstructure of poly(propylene oxide)-segmented polyamide and its suppression of platelet adhesion.

Abstract: The relationship between microphase-separated structures and antithrombogenicities of poly(propylene oxide) (PPO)–segmented polyamides of various polyamide segment lengths was studied. Transmission electron microscopic observation revealed fibrillar lamella structures to be present on the copolymer surfaces. Dynamic mechanical and thermal scanning measurements showed the existence of two mechanical relaxations attributable to micro-Brownian motions of the PPO and polyamide segments, indicating that the PPO and polyamide segments formed distinctly separated microdomain structures. Moreover, wide-angle X-ray diffraction and small-angle X-ray scattering measurements indicated these copolymers to be different in their microstructures with respect to size and distribution of crystalline and amorphous domains even though the crystalline structure was essentially the same as that of nylon 610. The degree of platelet adhesion and aggregation was significantly minimized on the surface of the copolymer, in which the average diameter of the crystalline and amorphous domains were 6.42 nm and 5.18 nm, respectively. This suggests that the size of segmented polyamide microdomains may be a determining factor in antithrombogenicity.

Polymer membrane as a reaction field. II. Effect of membrane environment on permselectivity for water-ethanol binary mixtures

Abstract: Polymer Membrane as a Reaction Field II. Effect of Membrane Environment on Permselectivity for Water–Ethanol Binary Mixtures

Surface Characterization of Soap-Free Carboxylated Polymer Latices

Abstract: The surface characteristics of carboxylated polymer latices—styrene/acrylic acid copolymer (PS/PAA) and styrene/methacrylic acid copolymer (PS/PMAA)— were investigated. Polystyrene (PS) latex was used as a reference sample. These latices were prepared in a soap-free system, using potassium persulfate as the initiator. Conductometric titration curves of PS and carboxylated latices showed both strong and weak acid groups to exist on the surface of latex particles. The surface charge density (σ) for PS/PAA latex was proportional to the amount of acrylic acid (AA) used in the copolymerization (thus, σ- for PS/PAA5 latex was larger than that for PS/PAA2 latex; the subscripts 5 and 2 represent the mol% of AA monomers used in the copolymerization). However, σ for PS/PMAA5 latex was smaller than that for PS/PAA5 latex, although the mol% of acid monomers used in the copolymerization was the same for both latices. σ for carboxylated latices increased with increasing pH, but the pH dependence of σ for PS latex was not very pronounced. The ζ-pH curves for these latices were considerably different from the σ-pH curves. This is probably because the Stern potential and the position of the shear plane in the electrical double layer differ between the two latices. Methylene Blue adsorption onto PS and PS/PAA latices was measured as a function of pH. The overall tendency of the dye adsorption was more similar to the σ-pH curves than the ζ-pH curves.

The carbon-13 NMR chemical shift of poly(1-butene) referring to that of 2,4,6,8,10,12,14,16,18-nonaethylnonadecane and a comparison of the chemical shifts between poly(1-butene) and polypropylene

Abstract: The chemical shifts were calculated for diastereomers of 2,4,6,8,10,12,14,16,18-nonaethylnonadecane (NEND), in which the methylene C9 and methine C10 of the backbone chain and methylene C10 and methyl C10 of the side chain serve as models of CH2 (backbone), CH, CH2 (side chain), and CH3 of poly(1-butene) (PB), respectively. The so-called γ effect and Suter–Flory rotational isomeric model were taken into account in the calculation. Additional repulsive interaction, τ*=0.6 between the ethyl group of the side chain and backbone was also considered when both adjacent backbone bonds were trans. The γ interaction was clarified to be important between the methylene carbons of the backbone chain and methyl carbons of the side chain. The methylene (tetrad) and methine (pentad) carbons of the backbone chain and the methylene (pentad) and methyl (pentad) carbons of the side chain of isotactic PB were successfully assigned to stereosequences by a comparison with the calculated spectra of NEND. A similar calculation was done for the chemical shifts of the methylene C9, methine C10, and methyl C10 of 2,4,6,8,10,12,14,16,18-nonamethyl nonadecane as a polypropylene (PP) model in order to determine the propriety of the calculated chemical shifts for NEND by comparison. Agreement between the calculted and observed chemical shifts of all carbons was excellent for both PB and PP.

Cloud point curve and critical point of multicomponent polymer/single solvent system.

Abstract: An attempt was made to establish a theoretical method for calculating the cloud point curve (CPC) and critical point of solutions of polydisperse polymers in a single solvent (i.e., quasi-binary system) on the basis of the polydispersity of the polymer and concentration- and molecular weight-dependences of the polymer–solvent thermodynamic interaction parameter χ. Expressions giving the cloud point curve were derived and a computer simulation technique, based on the theory, was developed. The effects of the average molecular weight, polydispersity of polymer and concentration dependence of χ-parameter on CPC, threshold cloud point and critical point were clarified. In order to represent accurately the CPC for the entire concentration range from the molecular characteristics of the original polymer and operating conditions, such as polymer–volume fraction and χ-parameter, the concentration dependence parameters p1 and p2, in the relation χ=χ0(1+p1vp+P2νp2) (χ0; concentration-independent parameter, vp, polymer volume fraction) should be adequately taken into account. Very delicate changes in p1 and p2 cause significant variation in CPC and none of the literature data on p1 and p2 for polystyrene/ cyclohexane adequately represent the experimental CPC. From an actual CPC experiment, p1=0.643 and p2=0.200 were evaluated. The effective role of the molecular weight dependence of χ in CPC was shown in the lower vp region.

Stiff-Chain Behavior of Poly(terephthalamide- P -benzohydrazide) in Dimethyl Sulfoxide

Abstract: Fifteen fractionated samples of poly(terephthalamide-P-benzohydrazide) (PPAH) ranging in weight-average molecular weight from 2×103 to 6×104 were studied by light scattering, sedimentation equilibrium, and viscometry with dimethyl sulfoxide (DMSO) at 25°C as the solvent. The data obtained for the radius of gyration, the optical anisotropy factor, and the intrinsic viscosity showed the PPAH chain in DMSO to be semiflexible. Analysis of these data in terms of current theories for the Kratky–Porod wormlike chain gave 11.2±0.5 nm, 185±5 nm−1, 0.5 nm, and 2.1 for the persistence length, molar mass per unit contour length, diameter, and optical anisotropy [= 3(α1–α2)/(α1+2α2)] of the PPAH chain in DMSO, respectively. Here, α1 and α2 are, respectively, the longitudinal and transverse polarizabilities per unit contour length of the chain.

Grafting of polyesters on carbon black V. Preparation of polyester-grafted carbon black with a higher grafting ratio by the copolymerization of epoxide with cyclic acid anhydrides using COOK groups on carbon black as the initiator.

Abstract: The ring-opening copolymerization of epoxides with cyclic acid anhydrides was found to be initiated by carbon black containing potassium carboxylate (COOK) groups to give alternating polymers, i.e., polyesters. Polyesters were propagated from COOK groups and effectively grafted on carbon black; for example, the grafting ratios of polyesters from glycidyl methacrylate and succinic anhydride and from styrene oxide and maleic anhydride were 126.2 and 51.5%, respectively. The rate of copolymerization increased with increasing temperature, whereas the grafting ratio of polyesters decreased. The initiating activity of alkali metal carboxylate groups increased, depending on the type of alkali metal countercations, in the following order: COOLi < COONa < COOK < COORb < COOCs. This order was in agreement with that of increasing electropositivity of the countercations. In addition, the increasing electropositivity of the counter-cation caused an increase in the rate of chain transfer reaction, leading to a decrease in the grafting ratio and molecular weight of ungrafted polyesters. The effects of solvent on the copolymerization and grafting ratio are discussed.

Magnetic Properties of Poly[5-(4-acryloyloxyphenyl)-10,15,20-triphenylporphinatocopper(II)] and Poly[5-(4-acryloyloxyphenyl)-10,15,20-triphenylporphinatosilver(II)]

Abstract: The magnetic properties of polymers containing tetraphenylporphin-Cu(II) (TPP-Cu(II)) or tetraphenylporphin-Ag(II) (TPP-Ag(II)) in the side chains were studied by the magnetic susceptibility (χM) measurement (4—300 K) and ESR spectroscopy. The values of χM for the polymer containing TPP-Cu(II) were found to obey the Curie–Weiss law, and a magnetic moment showed the occurrence of a weak antiferromagnetic interaction between Cu(II) ions. The values of χM for the polymer containing TPP-Ag(II) did not obey any simple equation such as the Curie–Weiss law or Bleaney–Bowers equation and simulation of temperature dependence of χM showed the presence of strongly interacting sites. This strong interaction may possibly arise from a hyperexchange interaction through C = O groups situated among the Ag(II) ions. An ESR study also supported the presence of this interaction between the side groups in a polymer chain.

Synthesis and Thermal Properties of Polyurethane, Poly(butyl methacrylate), and Poly(methylmethacrylate) Multi-Component IPN’s

Abstract: Three component interpenetrating polymer networks (IPN’s) of polyurethane (PU)–poly(n-butyl methacrylate) (PBMA)–poly(methyl methacrylate) (PMMA) were prepared by the combined synthesis of simultaneous polymerization and sequential polymerization Two types of IPN’s, (PU–PMMA)–PBMA and (PU–PBMA)–PMMA, were obtained by forming PU–PMMA (or PU–PBMA) simultaneous IPN’s first and then swelling the network in BMA (or MMA) and ethylene dimethacrylate (EDMA) monomer mixtures followed by sequential polymerization of the imbibed monomers The glass transition behavior studied by DSC and DMA showed three separate but broad Tg’s for (PU–PMMA)–PBMA IPN’s, while two Tg’s (one broad Tg for PU transition and the other broad Tg at intermediate temperature of PMMA and PBMA transition) were observed for (PU–PBMA)–PMMA IPN’s Both three component IPN’s showed high damping characteristics (tanδ=02—04) in the temperature range of −30—90°C The TGA analysis revealed enhanced thermal stability in all of the two-component and three-component IPN’s of polyurethane and polymethacrylate

Photoresponsive permeation characteristics of a ternary composite membrane of polymer/artificial lipid/azobenzene derivative.

Abstract: A ternary composite membrane composed of polymer/artificial lipid/azobenzene derivative was prepared by casting from a tetrahydrofuran solution of poly(vinyl chloride) (PVC), dioctadecyldimethylammonium bromide (DOAB) and p-ω-hydroxypropyloxy-p′-dodecyloxy azo-benzene (AZO). AZO dispersed almost molecularly within the multilayer liposome of artificial lipid (DOAB), and even in the ternary composite membrane, AZO exhibited trans–cis photoisomerization in a similar manner to that in solution. The water or ion permeations through the composite membrane apparently increased upon the irradiation of ultraviolet (UV) light when artificial lipids were in a liquid crystalline state. The water permeability coefficient, P depended on the trans-fraction of AZO. This suggests that the conformational change due to the trans–cis photoisomerization of AZO makes compact packing of artificial lipid molecules around AZO loosed, being followed by formation of permeation channel.

Permeability through cellulose membranes grafted with vinyl monomers in homogeneous system. II. States of water in acrylonitrile grafted cellulose membranes.

Abstract: Differential scanning calorimetry was used to investigate the states of water in cellulose membranes grafted with acrylonitrile (AN). Examination of the melting endotherms and freezing exotherms showed the existence of three water states differing in their interaction with polymer molecules: free water, intermediate water, and bound water. The amount of intermediate water was remarkably reduced by grafting AN onto cellulose. The amounts of freezing water and nonfreezing water were estimated to elucidate the diffusive permeability of solutes through the membranes. The difference in permeability through the membranes may be explained by the difference in freezing water content. The intermediate water may not be appreciably related to the permeation of solutes through the membranes.

Phase Equilibrium of the Ternary System Consisting of Two Monodisperse Polystyrenes and Cyclohexane

Abstract: Phase Equilibrium of the Ternary System Consisting of Two Monodisperse Polystyrenes and Cyclohexane

Permeability through cellulose membranes grafted with vinyl monomers in a homogeneous system. I. Diffusive permeability through acrylonitrile grafted cellulose membranes.

Abstract: The homogeneous graft copolymerization of acrylonitrile onto cellulose was carried out in a dimethyl sulfoxide (DMSO)-paraformaldehyde solvent system. Three kinds of membranes were prepared: higher grafting efficiency membranes (H-GE membrane), lower grafting efficiency membranes (L-GE membrane), and blended membranes. The diffusive permeability of solutes through the water-swollen membranes was investigated. The permeability and microphase separated structure depended remarkably on the kind of membrane. Permeability through the H-GE membranes increased with increasing polyacrylonitrile content and leveled off, but that through the L-GE and blended membranes decreased. Permeability through the H-GE membranes was superior to that through the cellulose membrane cast from the DMSO solution of cellulose. However, the good permeability through the H-GE membranes could not be explained by the difference in water content of membranes.