Raman scattering from mixtures of poly(ethylene oxide) 2000 with poly(ethylene oxide) 200

The longitudinal acoustic mode fundamental (v₁) and third harmonic (v₃) in 2000 MW PEO with both hydroxy- and methody-end-groups have been observed in the Raman spectrum as a function of 200 MW PEO oligomer content. Measurements of small-angle X-ray spacing I_x permit interpretation using a composite rod model. A good fit to the measured quantities v₁I_x and $\text{v}{}_3\text{v}{}_1$ is obtained with crystal length I_c≈9 nm, crystal modulus $\text{E}{}_{\mathrm{<mtext>c</mtext>}}\text{= 9 ×}\text{10}{}^{10}\text{N}\text{m}{}^2$ and amorphous modulus $\text{E}{}_{\mathrm{a}}\text{= 1 ×}\text{10}{}^{10}\text{N}\text{m}{}^2$. The value of Ic implies a crystalline content of ～70% for the pure polymer; the value of Ec is larger than static determinations and similar discrepancies in other materials are discussed.     

Ionic conductivities of poly(methoxy polyethylene glycol monomethacrylate) complexes with LiSO3CH3

Ionic conductivity values for LiSO₃CF₃ complexes with two amorphous poly(methoxy polyethylene glycol monomethacrylates) (PEM) were determined and values as high as $\text{～6 × 10}{}^{\mathrm{?4}}\text{Ω}{}^{\mathrm{?1}}\text{cm}{}^{\mathrm{?1}}$ at 373 K and $\text{～2 × 10}{}^{\mathrm{?5}}\text{Ω}{}^{\mathrm{?1}}\text{cm}{}^{\mathrm{?1}}$ at 293 K were achieved. These values are compared with those obtained for a poly(ethylene oxide) (PEO)-LiSO₃CF₃ complex of similar salt concentration with an ether oxygen to Li⁺ ion ratio of 18. The conductivity results for the complexes are similar at temperatures >343 K but at 293 K the values for the conductivities of the PEM-LiSO₃CF₃ complexes are approximately two orders of magnitude higher than those for the PEO-LiSO₃CF₃ complex. This difference is believed to be due at least in part to the presence of a large amount of crystalline material in the PEO-LiSO₃CF₃ complex below 323 K.     

Phosphonitrilic chloride: 34. Electrical conductivity of polybisaminophosphazenes

The electrical conductivity of polybisaminophosphazenes investigated over a range of temperatures was found to obey the general relation for semi-conductors. The resistivity decreased or increased when a side group having a high inductive effect or bulky group was linked in the polymers. The electrical conductivity of polybisaminophosphazenes containing primary amine, secondary amine and aromatic amine ranged from 1.3 × 10¹⁰ to $\text{2.8 × 10}{}^{10}\text{Ω-}\text{cm}$, 9.3 × 10¹⁰ to $\text{8.5 × 10}{}^{11}\text{Ω-}\text{cm}$ and above $\text{9.1 × 10}{}^{14}\text{Ω-}\text{cm}$, respectively.     

Conformation of poly(ethylene oxide) in the solid state,melt and solution measured by Raman scattering

The Raman spectrum of poly(ethylene oxide) (PEO) $\text{M}\text{?}{}_{\mathrm{w}}\text{= 3 × 10}{}^6$ and 6 × 10³ has been measured in bulk as a function of temperature and in aqueous and chloroform solution as a function of solvent concentration. The spectral features are assigned to particular isomeric configurations and the changes on melting are found to be consistent with a helix-coil transition. In both solvents the ordered nature of the polymer is largely lost at a critical concentration, approximately 50% by weight; residual ordering in dilute aqueous solution is lost and the random coil configuration attained only above the melting temperature. The wavenumber change of the 862 cm^?1 mode as a function of water concentration showed formation of a complex involving three water molecules and was consistent with a simple H-bonding model. The differences between the spectra in the two solvents are explained by this H-bonding. The results are in general agreement with n.m.r. work.     

Self-diffusion of poly(ethylene oxide) in aqueous dextran solutions measured using FT-pulsed field gradient n.m.r.

Transport in ternary polymer₁, polymer₂, solvent systems has been investigated using an n.m.r. spin-echo technique. The dependence of the self-diffusion coefficient of poly(ethylene oxide) polymers on the concentration and molecular size of dextran in aqueous solution has been measured. Monodisperse poly(ethylene oxide) fractions ($\text{M}\text{?}{}_{\mathrm{w}}\text{=7.3×10}{}^4$, 2.8·10⁵ and 1.2·10⁶) and dextrans ($\text{M}\text{?}{}_{\mathrm{w}}\text{=2·10}{}^4$, 1·10⁵ and 5·10⁵) have been employed over a range of concentration up to the miscibility limit in each system. It is found that when the molecular size of the diffusant is commensurate with or exceeds that of the matrix polymer, a relationship of the form: $\text{(}\text{D}\text{D}{}_0\text{)}{}_{\mathrm{<mtext>PEO</mtext>}}\text{=}\text{exp}\text{?k(C[η])}$ is applicable, where C[η] refers to the dextran component and is considered to describe the extent of coil overlap in concentrated solution. ($\text{D}\text{D}{}_0$) is independent of the molecular size of the poly(ethylene oxide), at least in the range studied (M_w<300 000).     

Gas-liquid chromatography study of poly(ethylene oxide)-solvent interactions: estimation of polymer solubility parameter

The thermodynamics of the interactions in the liquid state (70°–150°C) between poly(ethylene oxide) ($\text{M}\text{?}{}_{\mathrm{n}}\text{= 10}{}^4$) and 32 solvents covering a wide range of structure and polarity (from n-hexane to 2,2,2-trifluoroethanol) were studied by gas-liquid chromatography. The regular solution theory, in spite of its well known limitations, does allow a very self-consistent interpretation of all the data for the systems characterized by a positive Flory parameter χ, including systems of poly(ethylene oxide) and a self-associated alcohol where specific hydrogen bonding is well known. The polymer solubility parameter δ₂ (δ₂ = 9.6 ± 0.1 (cal cm^?3)^0.5 at 70°C and its temperature dependence are easily derived with good accuracy.     

The unperturbed molecular dimensions of poly(ethylene oxide) in aqueous solutions from intrinsic viscosity measurements and the evaluation of the theta temperature

Intrinsic viscosity measurements were carried out on five well characterized fractions of poly(ethylene oxide) in aqueous solutions at 24.9°, 34.9°, and 45.5°C. The Stockmayer-Fixman extrapolation was applied to the data: it yields the unperturbed dimensions K₀ of the chain. The unperturbed root-mean-square end-to-end distance $\text{〈}\text{R}\text{?}{}^2\text{〉}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}_0$ calculated for the polymer fractions in water indicate that the polymer molecules are expanded in this solvent as the temperature is raised. The temperature coefficient of unperturbed dimension, $\text{d In}\text{〈}\text{R}\text{?}{}^2\text{〉}{}_0\text{d}\text{t}\text{= 0.024}\text{K}{}^{\mathrm{?1}}$, calculated for poly(ethylene oxide) in water using the present data is about 100 times higher than the literature values of 0.23 (±0.02) × 10^?3 K^?1 and 0.2 (±0.2) × 10^?3 K^?1, respectively, obtained from force-temperature (‘thermoelastic’) measurements on elongated networks of the polymer in the amorphouse state and form viscosity measurements on this polymer in benzene. A value of θ=108.3°C was obtained from the temperature dependence of the interaction parameter B in the Stockmayer-Fixman equation.     

Phosphonitrilic chloride: 21. Synthesis of chelating polymers with cyclophosphazene thiocarbamate and the properties of chelating polymers

Chelating polymers containing copper, nickel and cobalt have been formed from cyclophosphazene thiocarbamate trimer and copper, nickel or cobalt ions. These polymers obtained from the reaction are amorphous and the values of electron conductivity are $\text{2·7 × 10}{}^{11}\text{Ω-}\text{cm}$, $\text{3·6 × 10}{}^{13}\text{Ω-}\text{cm}$ and $\text{1·5 × 10}{}^{13}\text{Ω-}\text{cm}$ for the Cu, Ni and Co polymers respectively. The Cu polymer is the most thermally stable on heating to 500°C in air.     

Characterization of poly(1,4-phenyleneterephthalamide) in concentrated sulphuric acid: 1. Static and dynamic properties

Laser light scattering including angular dependence of total integrated scattered intensity and of the spectral distribution has been used to characterize five samples of poly(1,4-phenylene terephthalamide), PPTA (commercially known as Kevlar), of different molecular weights in 96% sulphuric acid and 0.1 NK₂SO₄. The data are supplemented by intrinsic viscosity measurements used to detect the possible effects of association, by differential refractometry providing a measure of the refractive index increments in mixed solvents (H₂O, H₂SO₄ and K₂SO₄) and by spectrophotometry for the extinction coefficient needed in the correction of attenuation in light scattering studies. The results show 〈D〉Z = 2.11 × 10^?5$\text{M}\text{?}{}_{\mathrm{<mtext>W</mtext>}}{}^{\mathrm{?0.75}}\text{cm}{}^{\mathrm{?2}}\text{s}{}^{\mathrm{?1}}$ in reasonable agreement with an average of many of the published intrinsic viscosity data obeying [η] = 1.09 × 10?3 M_w^1.25 ml g^?1 and _w expressed in g mol^?1.     

Effect of molecular weight on spherulite growth rates of high molecular weight poly(ethylene oxide) fractions

Spherulite growth rates have been determined for a set of poly(ethylene oxide) fractions ranging in molecular weight from 10⁴ to 10⁶. At a given crystallization temperature the spherulite growth rate as a function of molecular weight passes through a maximum. At a given undercooling (as assessed by the method of Mandelkern) the spherulite growth rate is a monotonically decreasing function of molecular weight, and in the range $\text{6000 <}\text{M}\text{?}{}_{\mathrm{v}}\text{< 50 000}$ varies roughly as $\text{(}\text{M}\text{?}{}_{\mathrm{v}}\text{)}{}^{\mathrm{?3}}$. The free energy of formation of the end interface (as assessed by nucleation theory) also decreases as molecular weight increases.     

Poly(ortho-vinylbenzophenone)

This article reports the synthesis and free radical polymerization of ortho-vinylbenzophenone. The glass transition temperature T_g of the homopolymer is 136°C. The products synthesized appeared to be atactic and amorphous. The Mark-Houwink constants for poly (o-vinylbenzophenone) in tetrahydrofuran are K = 4.2 × 10^?2 cm³ g^?1 and a = 0.765. The pre-exponential constant under theta conditions, K_θ, is estimated to be 5.93 × 10^?2 cm³ g^?1. The ratio of unperturbed dimensions of the actual polymer and free rotating analogue chain is 3.93, which is almost double that of polystyrene. The Flory-Huggins interaction parameter for poly $\text{(o-}\text{vinylbenzophenone}\text{)}\text{tetrahydrofuran}$ is 0.48 at room temperature. The $\text{k}{}_{\mathrm{<mtext>p</mtext>}}\text{k}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}_{\mathrm{<mtext>t</mtext>}}$ ratio at 60°C is $\text{1.1 × 10}{}^{\mathrm{?2}}\text{l}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{mol}{}^{\mathrm{<mtext>?1</mtext><mtext>2</mtext>}}\text{s}{}^{\mathrm{<mtext>?1</mtext><mtext>2</mtext>}}$. In free radical copolymerizations with styrene at 70°C, r₁ (o-vinylbenzophenone) = 1.216, r₂ = 0.751. This copolymerizations is virtually random.     

Unperturbed dimensions of poly(phenyl acrylate)

Thirteen fractions of poly(phenyl acrylate) have been prepared with weight-average molecular weight ranging from 0.158 × 10⁶ to 2.57 × 10⁶ g mol^?1. The temperature coefficient of the unperturbed dimensions and the glass transition temperature were found to be ?1.8 × 10^?3 deg^?1 and 55.6°C respectively. Good accord was obtained among different methods for establishing θ-conditions of 11.5°C in ethyl lactate. From viscometry, osmometry and light scattering under θ-conditions, as well as in a good solvent, the unperturbed dimensions were determined via several procedures yielding a value of $\text{[〈r}{}^2\text{〉}{}_{\mathrm{0w}}\text{M}\text{?}{}_{\mathrm{w}}\text{]}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 6.0 (±0.2) × 10}{}^{\mathrm{?9}}\text{cm g}{}^{\mathrm{<mtext>?1</mtext><mtext>2</mtext>}}\text{mol}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$. This corresponds to a steric factor υ = 2.37 (±0.08) and a characteristic ratio C_∞ = 11.3 (±0.8). The polymer chain is thus more rigid than poly(methyl acrylate), but less rigid than poly(phenyl methacrylate). With respect to its T_g and flexibility, poly(phenyl acrylate) bears a strong similarity to poly(benzyl methacrylate).     

Studies of cyclic and linear poly(dimethyl siloxanes): 3. Neutron scattering measurements of the dimensions of ring and chain polymers

The dimensions of both cyclic and linear poly(dimethyl siloxanes) in dilute solution in benzene-d₆ have been measured by small-angle neutron scattering. The mean-square radii of gyration of the linear polymers are consistent with values predicted from published data, including experimental molar cyclization equilibrium constants. The average dimensions of the cyclic poly(dimethyl siloxanes) in fractions containing z-average numbers of bonds $\text{n}\text{?}{}_{\mathrm{z}}$ in the range $\text{130 <}\text{n}\text{?}{}_{\mathrm{z}}\text{< 550}$, were found to be considerably smaller than those of the corresponding linear polymers. The neutron scattering results give a value for the ratio of the z-average radii of gyration for linear and ring poly(dimethyl siloxanes) (containing the same number of monomer units) $\text{〈s}{}^2\text{〉}{}_{\mathrm{z,l}}\text{<s}{}^2\text{〉}{}_{\mathrm{z,r}}\text{= 1.9 ± 0.2}$. This ratio may be compared with the value of 2.0 predicted theoretically for ‘flexible’ high molecular weight linear and cyclic polymers, unperturbed by excluded volume effects.     

Branched poly(ethylene terephthalate) correlations between viscosimetric properties and polymerization parameters

Samples of poly(ethylene terephthalate) (PET) modified with small amounts of trimesic acid groups and hence containing long chain branching have been prepared. From the content of trifunctional modifier and from the experimental value of the extent of reaction, the weight-average molecular weight $\text{M}\text{?}{}_{\mathrm{w}}$ and branching density $\text{B}\text{?}{}_{\mathrm{w}}$ have been calculated, assuming that all the end-groups are equally reactive and intramolecular reactions are absent. The values of $\text{M}\text{?}{}_{\mathrm{w}}$ and $\text{B}\text{?}{}_{\mathrm{w}}$ have been correlated with the experimental values of intrinsic viscosity [η] and the Newtonian melt viscosity η₀. General relations of the following type have been obtained:

$\text{f}{}_1\text{([η],}\text{M}{}_{\mathrm{w}}\text{,}\text{B}{}_{\mathrm{w}}\text{) = 0; f}{}_2\text{(η}{}_0\text{,}\text{M}{}_{\mathrm{w}}\text{,}\text{B}{}_{\mathrm{w}}\text{) =0; f}{}_3\text{(η}{}_0\text{, [η],}\text{B}{}_{\mathrm{w}}\text{) = 0; f}{}_4\text{(η}{}_0\text{, [η],}\text{M}{}_{\mathrm{w}}\text{) = 0;}$

In particular, [η] and η₀ increase on increasing $\text{M}\text{?}{}_{\mathrm{w}}$ and decrease on increasing $\text{B}\text{?}{}_{\mathrm{w}}$, but, at equal [η] values, η₀ increases with $\text{B}\text{?}{}_{\mathrm{w}}$. Through the last relation, the reliability limits of which should be experimentally checked, and from measurements of [η] and η₀, it is possible to calculate $\text{M}\text{?}{}_{\mathrm{w}}$ of a branched PET.     

Synthesis of electroreactive polymers from poly (m,p-chloromethylstyrene) and copoly (m,p-chloromethylstyrene-styrene)

Polymerization, and copolymerization with styrene, of m,p-chloromethylstyrene have been carried out at 75°C, in chlorobenzene and in the presence of AIBN ($\text{[}\text{AIBN}\text{] ? 6 × 10}{}^{\mathrm{?2}}$, and $\text{12 × 10}{}^{\mathrm{?2}}\text{m}$, respectively). The polymer molecular weights, determined by g.p.c., are: $\text{M}\text{?}{}_{\mathrm{w}}\text{= 8670}$, $\text{M}\text{?}{}_{\mathrm{n}}\text{= 5860}$, and $\text{M}\text{?}{}_{\mathrm{w}}\text{/-M}{}_{\mathrm{n}}\text{= 1.48}$ for the homopolymer, poly(m,p-chloromethylstyrene), (1a); and $\text{M}\text{?}{}_{\mathrm{w}}\text{= 8805}$, $\text{M}\text{?}{}_{\mathrm{n}}\text{= 5144}$, and $\text{M}\text{?}{}_{\mathrm{w}}\text{/-M}{}_{\mathrm{n}}\text{= 1.71}$ for the copolymer, copoly(m,p-chloromethylstyrene-styrene), (2a). A series of phosphine derivatives of both 1a and 2a are prepared by the reaction of the polymers with either chlorodiphenylphosphine/lithium, or diphenylphosphine/potassium tert. butoxide. A number of other potentially electroreactive derivatives of 2a are obtained by reacting the polymer with 2-aminoanthraquinone, 3-N-methylamino-propionitrile, or 2-(2-aminoethyl) pyridine. The phosphinated polymers are reacted with bis-benzonitrilepalladium-(II) chloride to obtain a series of polymer-palladium(II) complexes containing 8.5–12.9% palladium. Similarly, reaction of the last-named bidentate polymeric ligand with cupric acetylacetonate, or cupric sulphate pentahydrate, produces polymer-copper(II) complexes having 5.8, or 3.3% copper, respectively. The inter/intra-chain nature of some of the side reactions during the derivatization of the chloromethylated polymers, and that of the complex formation between transition metal centres and macromolecular ligands, are briefly discussed in view of the experimental results.     

Structure and properties of poly(ethylene terephthalate) crystallized by annealing in the highly oriented state: 2. Melting behaviour and the mosaic block structure of the crystalline layers

The melting behaviour of drawn poly(ethylene terephthalate) bristles has been studied by means of differential scanning calorimetry. In addition the wide-angle X-ray diffraction pattern were analysed. For comparison some of the experiments were also carried out with undrawn samples. The differences in the melting curves of drawn and undrawn PET originate from the different crystallization kinetics. The density defect ($\text{?}{}^{\mathrm{id}}{}_{\mathrm{c}}\text{? ?1}{}_{\mathrm{c}}$) between the ideal crystal density ?^id_c and the effective density $\text{?1}{}_{\mathrm{c}}$ of the crystalline layers is a result of lattice vacancies introduced by the grain boundaries of the mosaic blocks. The relatively low ultimate crystallinity of PET is supposed to be caused by the hindrance of crystal growth of fibre direction during isothermal crystallization.     

A study of molecular orientation in poly(methyl methacrylate) by means of laser-Raman spectroscopy

Measurements have been made of the polarization dependence of the intensity of the Raman scattering from uniaxially oriented samples of poly(methyl methacrylate). Lines at wavenumber shifts 486, 562, 604 and 1732 cm^?1 were studied. With the right-angle scattering geometry used, four combinations of polarization directions of incident and observed scattered light could be chosen and the angle between the draw direction and the direction of the incident laser beam could be varied. The observed intensities were found to fit equations derived in an earlier publication. Five parameters which would determine the scattered intensity for any scattering geometry and combination of polarization vectors were derived. They were shown to contain information about the distribution of orientations of the structural units of the polymer despite the fact that their values also suggest that either the nature of the structural units or the interactions between them are modified by drawing. Values of $\text{cos}{}^2\text{θ}$ and $\text{cos}{}^4\text{θ}$ deduced for the structural units, where θ is the angle between a unique axis in a typical unit and the draw direction, are in good agreement with those obtained by other authors from broadline n.m.r. measurements. For the sample with the highest birefringence, ?14.8×10^?4, the values of $\text{cos}{}^2\text{θ}$ and $\text{cos}{}^4\text{θ}$ were 0.52±0.03 and 0.43±0.04 respectively.     

Investigation of the methyl torsion in isotactic polypropylene — comparison between neutron inelastic scattering spectra and normal coordinate calculations

Incoherent neutron scattering spectra for polypropylene and its partially deuterated analogue allow identification of the methyl torsion at 230 cm^?1. Comparison of the experimental spectra with the calculated densities of states shows discrepancies with the expected intensity of the methyl torsional band. Results from a stretch-oriented sample arranged so that the wave vector $\text{Q}$ is first parallel ($\text{Q}{}^{\mathrm{\parallel }}$) and then perpendicular ($\text{Q}{}^{\mathrm{\perp }}$) to the helical chain axis indicate that the torsion is more intense and probably has a small frequency dispersion around 240 cm^?1 for $\text{Q}{}^{\mathrm{\parallel }}$ and is weaker with a broad dispersion centred at 220 cm^?1 for $\text{Q}{}^{\mathrm{\perp }}$.     

A calculation of the elastic constant c33 of a graphite crystal as a function of temperature

A calculation is presented of the elastic constant C₃₃ of a graphite crystal as a function of temperature up to 2500 K, taking into account the anharmonic contribution and the changes in interlayer interactions due to the large lattice thermal expansion. Parametric variations in the theory show that the anharmonic contribution to C₃₃ depends principally on the parameter ($\text{?}{}^2\text{C}{}_{33}\text{?e}{}^2{}_{\mathrm{zz}}$) Comparison of theoretical results with the experimental data, which is mainly from neutron scattering experiments, shows that the data can be accounted for if ($\text{?}{}^2\text{C}{}_{33}\text{?e}{}^2{}_{\mathrm{zz}}$) lies in the range 7–10 × 10¹³ dynes/cm². A theoretical estimate of ($\text{?}{}^2\text{C}{}_{33}\text{?e}{}^2{}_{\mathrm{zz}}$) based on Lennard-Jones potentials between atoms in adjacent basal planes gives a value of 9·07 × 10¹³ dynes/cm².     

Crystallization of block poly(ethylene oxide)

Urethane linked block polymers of poly(ethylene oxide) have been prepared and fractionated. Samples having 1 to 20 blocks per molecule, with molecular weights ranging from 1500 to 67 000 g/mol, have been examined by a number of techniques (small-angle X-ray scattering, differential scanning calorimetry, dilatometry, optical microscopy) in order to determine their crystallinities, melting points and spherulite growth rates. For a series of fractions having an average block length of 34 oxyethylene units with a range of 3 to 20 blocks per molecule, we find that equilibrium melting points are practically independent of molecular weight ($\text{6000 <}\text{M}\text{?}{}_{\mathrm{W}}\text{< 40 000}$). Analysis of the temperature dependence of the spherulite growth rates of these fractions leads to the conclusion that the pre-exponential factor (G₀) is practically independent of molecular weight and that the end interfacial free energy (σ_e) increases with molecular weight. Analysis of the experimental results for series of fractions having average block lengths of 45 or of 90 oxyethylene units is complicated by chain folding in the crystalline lamellae.