Solvent For Poly Research Articles

振動分光法で見るアクリルアミド誘導体ポリマーの局所構造と溶媒和―ポリ（Ｎ‐イソプロピルアクリルアミド）のコイル・グロビュール転移と局所構造変化

振動分光法で見るアクリルアミド誘導体ポリマーの局所構造と溶媒和―ポリ（Ｎ‐イソプロピルアクリルアミド）のコイル・グロビュール転移と局所構造変化

Characterization of Poly(ε-Caprolactone) via Size Exclusion Chromatography with Online Right-Angle Laser-Light Scattering and Viscometric Detectors

Poly( l -caprolactone) was characterized by size exclusion chromatography on-line with a right-angle laser-light scattering photometer and a four-capillary bridge design differential viscometer (SEC/RI/RALLS/DV) in tetrahydrofuran (THF) at 25°C. The dependence of intrinsic viscosity and radius of gyration of poly( l -caprolactone) on molecular weight was established, and Flory's characteristic ratio C X was calculated for this polymer from these data. The results show that THF is a good solvent for poly( l -caprolactone). Poly( l -caprolactone) exhibits a random-coil conformation in THF, and SEC with online RALLS and DV detectors offer an easy way to obtain information on chain flexibility. The C X results are in good accord with previously reported values for this polymer.

Change in Solvation of Poly(N,N-diethylacrylamide) during Phase Transition in Aqueous Solutions As Observed by IR Spectroscopy

Phase transitions of poly(N,N-dimethylacrylamide) (PdEA) in water and methanol/water mixture were investigated by Fourier transform infrared (FTIR) spectroscopy. IR spectra of the solutions measured as a function of temperature exhibited critical changes upon the phase transition. The amide I band of PdEA consists of three components centered at 1638, 1619, and 1599 cm-1, which can be assigned to free carbonyl groups and those connected to one and two water molecules through hydrogen bonds, respectively. The relative areas of the 1619 and 1599 cm-1 components decrease and that of the 1638 cm-1 component increases above the phase transition temperature (Tp), but the change is relatively small and most of the amide CO groups remain hydrated even above Tp. The C−H stretching bands shift toward lower wavenumbers that are close to those measured in the neat solid state, indicating that the alkyl groups are almost fully dehydrated above Tp. In the methanol/water mixture, Tp is almost independent of methanol concentration up to ca. 20% and increases steeply above ca. 30%. The heat of transition (ΔH) decreased linearly with an increase of methanol concentration up to 30% and is nearly zero above 40%. The areas of the 1599 and 1638 cm-1 bands decrease with an increase in methanol concentration with a slight change in the 1619 cm-1 band. The result suggests that methanol replaces parts of the CO···H−O−H hydrogen bonds to form a CO···H−O−CH3 hydrogen bond, and its bulky methyl group prevents the carbonyl group to form the second hydrogen bond that is responsible for the 1599 cm-1 band.

Organometallic Gels: Characterization and Electrochemical Studies of Swellable, Thermally Crosslinked Poly(ferrocenylsilane)s

Investigations on a series of crosslinked poly(ferrocenylsilane) networks that have been prepared via the ring-opening copolymerization of the silicon-bridged [1]ferrocenophane fcSiMe2 (fc = Fe(η-C5H4)2) with controlled amounts of a spirocyclic [1]ferrocenophane fcSi(CH2)3 are reported. These crosslinked poly(ferrocenylsilane)s have improved thermal stability relative to their linear counterparts. The swelling response was investigated as a function of temperature, solvent and crosslink density. As expected, the degree of crosslinking had a dramatic effect on the swelling in various media. From swelling measurements in a variety of liquids, it was determined that the best solvents for poly(ferrocenyldimethylsilane) are THF, chloroform, and dichloromethane. The solubility parameter (δ) for the linear homopolymer was found to be 18.7(7) MPa1/2. Reversible electrochemical oxidation of the gel was observed at oxidation potentials greater than 450 mV (vs Ag/AgCl), consistent with the oxidation potential of the linear homopolymer, and an intervalence charge transfer band was detected at 1300 nm for the partially oxidized material.

Experimental approaches to generate compositional gradients in the fully biodegradable polymer blend system based on poly(3-hydroxybutyric acid)

The fully biodegradable polymer blend films with compositional gradients from the surface to the inside of the films were prepared by the solution-diffuse technique. A solution of bacterial poly(3-hydroxybutyric acid) (PHB) in hexafluoro-2-propanol (HFIP), which is also a good solvent for poly(vinyl alcohol) (PVA), was cast on a PVA film and the solvent HFIP was evaporated. By controlling the solvent evaporation rate, the PHB/PVA blend film with a compositional gradient was obtained. The phase structure and biodegradation profile of the PHB/PVA blend film were found to be different from those of the corresponding blend film prepared by the conventional solution-cast method.

Diffusional Behavior ofn-Alkanes in Polypeptide Gel System with Highly Oriented Chains As Studied by Pulsed Field Gradient Spin Echo1H NMR Method

The diffusion coefficients (D) of n-alkanes, n-pentane and n-decane, and 1,4-dioxane as solvent in poly(γ-benzyl l-glutamate) (PBLG) gel with highly oriented α-helical chains were measured by pulsed field gradient spin echo 1H NMR spectroscopy, of which the structure was determined by X-ray diffraction. From the experimental results, it was found that the diffusion coefficients of n-pentane and n-decane in the PBLG gel for the direction parallel and perpendicular to the magnetic field are D∥ = 8.4 × 10-6 cm2/s and D⊥ = 6.4 × 10-6 cm2/s, respectively, and D∥ = 6.1 × 10-6 cm2/s and D⊥ = 5.0 × 10-6 cm2/s, respectively, which correspond to the directions parallel and perpendicular to the α-helical main chain.

Investigation of poly(dimethyl siloxane) (PDMS)–solvent interactions by DSC

Low temperature DSC was used to study the state of several solvents in poly(dimethyl siloxane) (PDMS) membrane and the influence on the sorbed solvents on PDMS crystallinity. No phase transition was detected on the DSC thermograms until −130°C, when the solvent content in polymer is low, independently of the solvent nature. This suggests a dispersion of the solvents as individual molecules in the PDMS matrix. At high solvent contents, part of the solvent crystallizes. Most of the crystallized solvent melts at a temperature close to the melting point of the bulk solvent, while the rest melts at a lower temperature. The DSC thermograms also show the change in crystallinity of swollen PDMS in different solvents. The poor solvent and the solvent of moderate power increase PDMS crystallinity due to the solvent-induced crystallization effect, while the good solvent reduces polymer crystallinity because of the solution effect.

Determination of solubility parameters for poly(3-hydroxyalkanoates)

The three dimensional solubility parameters defined by Hansen are based on dispersion forces between structural units, interaction between polar groups and hydrogen bonding. For polar polymers such as poly(3-hydroxyalkanoates), P(3HA), this approach was used to obtain the three coordinates of a solubility parameter in terms of: a dispersion part, a polar part and a hydrogen bonding part. Thirty-eight different solvents for poly(3-hydroxybutyrate), PHB, which are mentioned in the literature are examined by this method and the theoretical predictions are compared with the experimental reports. Another overall comparison between PHA polymers provides their Hansen and Hildebrand parameters for side chain lengths up to C 13. In this series a linear progression in calculated solubility parameters with side chain length was found. An Appendix provides information and data on calculation of the solubility parameters. While the solubility information is limited and only covers homopolymers, it should help to highlight some of the contradictions regarding PHB solubility. This semi-empirical approach is only valid for amorphous polymers hence crystallinity effects, which are important with PHB, as well as molecular weight effects still require analysis.

Enhanced Colloidal Stabilization via Adsorption of Diblock Copolymer from a Nonselective ϑ Solvent

Experimental measurements, interpreted with mean field theories, provide quantitative understanding of the stability of colloidal particles coated with a highly asymmetric diblock copolymer. Adsorption of poly((dimethylamino)ethyl methacrylate)/poly(n-butyl methacrylate) onto colloidal silica particles from 2-propanol, which is nonselective and a ϑ solvent for poly(n-butyl methacrylate), yields a very high surface coverage and a highly stretched brush. With increasing temperature, the adsorbed chains swell more than those in the bulk. Upon cooling, the dispersions exhibit thermodynamic stability well below the ϑ temperature of the nonadsorbed block. A simple mean-field theory rationalizes the stability as a consequence of the high surface coverage, which is attributed in turn to strong segmental adsorption of the short anchor block and negligible excluded volume interactions among the stabilizing chains.

Electrochemistry of N-vinyl-2-pyrrolidone and a non polymerizable analogue

According to previous studies, the electropolymerization of N-vinyl-2-pyrrolidone fits a cationic mechanism with grafting of the polymer onto the platinum anode. However, this article shows that the pyrrolidone substituent of N-VP is also involved in the anodic reaction in addition to the polymerizable vinyl double bond. This additional reaction in the potential range of interest was confirmed by the electrochemical oxidation of a non polymerizable analogue of N-VP, i.e. N-methylpyrrolidone. Therefore, at least two mechanisms can contribute to the electrodeposition of a polymer film in a solvent of poly N-VP: electrografting and polymer branching and/or crosslinking by species stemming from the electrooxidation of the pyrrolidone rings.

Dynamo-optical properties of poly(naphthylene oxadiazole)s in sulphuric acid

Flow birefringence induced in dilute solutions of poly[(1,4-naphthylene)-2,5-diyl-1,3,4-oxadiazole] and poly[2,6-naphthylene)-2,5-diyl-1,3,4-oxadiazole] in conc, sulphuric acid has been investigated. The shear optical coefficient was found for these polymers to be approximately double the value of that obtained in the same solvent for poly[( para-phenylene)-2,5-diyl-1,3,4-oxadiazole]. Rigid-chain behaviour of the polymers was characterized by hydrodynamic and dynamo-optical parameters evaluated with application of the worm-like chain model and the “method of similar structures”. Change in optical anisotropy of a chain unit induced by incorporation of naphthylene groups into the main chain has been evaluated.

Solvation of poly(vinyl alcohol) in water, ethanol and an equimolar water-ethanol mixture: structure and dynamics studied by molecular dynamics simulation

Solutions of a 15-mer of poly(vinyl alcohol) in water, ethanol and a 1 1 (mole fraction) mixture of water and ethanol have been studied by molecular dynamics simulations. The solvent structure near the solute is analysed in terms of radial distribution functions and hydrogen bonding. Results indicate a preferential solvation by water molecules. Hydrogen-bond life time analysis shows that solvent-solute hydrogen bonds are slightly longer-lived than solvent-solvent hydrogen bonds. However, the separation in time scales is not large enough to support the notion of a solvent-decorated polymer. An analysis of the polymer dynamics shows that the gauche ⇹ trans transitions of backbone dihedral angles are at least an order of magnitude slower than the renewal of intramolecular hydrogen bonds along the polymer chain. No coupling is observed between the two.

The solvation of poly(vinyl alcohol)

AbstractThe possible incorporation of water molecules within the crystal structure of poly(vinyl alcohol) is discussed. Modelling of the crystal structure suggested that water could be incorporated without severe disruption, and the effect on the X‐ray powder diffraction trace was simulated. The effect of variation in tacticity is discussed in terms of the nature of the hydrogen bonding. Simulated traces are compared with experimental data from atactic samples in which a change in the diffraction peak intensities is observed for samples crystallised with water present. This is compared with samples produced from nonaqueous solutions.

Influence of the Glass Transition on Solute Diffusion in Polymers by Inverse Gas Chromatography

The capillary-column inverse gas chromatography (CCIGC) method was used to determine diffusivity data for several solvents in poly(styrene) at conditions approaching infinite dilution of the volatile component. Measurements were made over a temperature range traversing the polymer glass transition temperature. The chromatographic data were analyzed by employing the elution model developed by Pawlisch et al. The Vrentas-Duda free-volume theory of diffusion was utilized to correlate the diffusion data and to interpret the effect of the glass transition temperature on the diffusion coefficient and on the effective activation energy in the limit of zero penetrant concentration. The free-volume theory was found to correlate the diffusion data very well. The results of this study confirmed the free-volume concept that molecular diffusion is not as inhibited as one might expect below the glass transition temperature of the polymer.

On the Modification of Chitosan Through Grafting

Abstract The feasibility of grafting poly(methyl acrylate) and poly[1-(methoxycarbonyl) ethylene] onto chitosan, poly-β(1←-4)-2-amino-2-deoxy-d-glucose, was investigated. The grafting reaction was carried out in aqueous solution by using ferrous ammonium sulfate (FAS) in combination with H2O2 as redox initiator. The effects of such reaction variables as chitosan, monomer and initiator concentrations, reaction time, and reaction temperature were determined. Through this study the grafting reaction could be optimized. The grafting yield reached its maximum value of 332% when 0.3 g chitosan was copolymerized with 3 mL monomer at 70°C for 120 minutes with [FAS] = 6 × 10−5 M, [H2O2] = 6 × 10−3 M, and 8 mL water. The grafted chitosan was found to be insoluble in solvents for chitosan and solvents for poly(methyl acrylate), but did show swelling in dilute acetic acid, methanol, acetone, and in an ethanol/2% acetic acid 1:1 mixture. The thermal stability of chitosan and grafted chitosan were studied by dynamic th...

Sorption and diffusion of water and organic solvents in poly(β-hydroxybutyrate) films

The diffusion and solubility of water and organic compounds in poly(β-hydroxybutyrate) (PHB) at room temperature has been investigated. It was shown that the supermolecular structure of PHB films affects sorption of water and the thermostability of specimens. Analysis of the solubility of low molecular compounds in PHB was based on the thermodynamics of the regular solution. Correlation between solubility of compounds in PHB and the parameters of solubility was observed. A dependence of the diffusion coefficient D on the solvent concentration in the polymeric matrix was found.

Swelling of interpenetrating polymer networks

AbstractWe have studied the densities, kinetics, and equilibrium degree of swelling in a number of different solvents of poly(carbonate urethane)/poly(methyl methacrylate) and poly(carbonate urethane)/poly(vinyl pyridine) interpenetrating polymer networks (IPN's). The kinetics of solvent uptake are often anomalous. The equilibrium extent of swelling reflects, among other factors, the number of phases present. © 1993 John Wiley & Sons, Inc.

Cyclic ureas as solvents for poly(aryl ether) synthesis

The synthesis of various poly(aryl ethers) and related small molecule compounds were examined using the cyclic urea 1,3-Dimethyl-3,4,5,6-tetrahydro-2(IH)-pyrimidinone (N,N′-dimethylpropylene urea, DMPU) as the solvent. The results showed that generally higher molecular weight or yields were obtained under less stringent conditions, as compared to other common polymerization solvents. The enhancement was most notable for polymerizations involving aryl fluorides with a lower reactivity than conventionally activated dihalide monomers, e.g. ketones, sulfones. Poly(aryl ethers) displayed excellent solubility in DMPU, which was beneficial in the cases where more rigid heterocyclic-aryl ether polymers are formed.

Characterization of benzene as a solvent for poly(2-vinylpyridine)

Characterization of benzene as a solvent for poly(2-vinylpyridine)

An inverse gas chromatography study of sorption in polyphenylene oxide

The solubility coefficients of a number of good solvents in poly(2,6-dimethylphenylene oxide) (PPO) † † The authors wish to thank Doctor M. Blege (I.M.K. Akad. Nauk ChSFR), who kindly supplied the specimen of PPO. are determined over the temperature range 80–250°C by inverse gas chromatography. The retention diagrams on this polymer are linear in the region of the polymer glass transition temperature, which is associated with the absence of diffusional restrictions during chromatography. The excess enthalpy and entropy of mixing are calculated from the chromatography data. As for other glass-like polymers having a high free volume, a characteristic feature of PPO is its exothermal mixing, high negative entropy effects for some sorbates, and an extremal dependence of the enthalpy and entropy of mixing on the molar volume of the sorbate. This provides a means of evaluating the characteristic size of the non-equilibrium free volume element in the polymer.