Unperturbed dimensions of poly-p-chlorostyrene

Viscosity measurements on poly-p-chlorostyrene (PPCS) in benzene-methanol mixtures have been carried out at their corresponding theta temperatures determined by the phase separation method. Viscosity measurements were also run in benzene at the same temperatures. The Stockmayer-Fixman extrapolation method was applied to the data to obtain the chain unperturbed dimensions. K_θ. It was found that these, for PPCS in benzene, decrease with increasing temperature and that, both in benzene and in binary mixtures, they decrease with increasing values of the parameter a from the relationship [η] = KM^α. PPCS theta temperature in benzene was 8.     

Solution properties and unperturbed dimensions of poly(p-tert-butylstyrene)

The conformational and thermodynamic properties of poly(p-tert-butylstyrene) were investigated by osmometry, intrinsic viscosity, light scattering, gel permeation chromatography and phase equilibria measurements. Polymeric samples were anionically synthesized. 1-Nitropropane was found to be a θ-solvent for this polymer and the θ-temperature was determined as 31°C. Intrinsic viscosity-molecular weight relationships were obtained in a few solvents. Unperturbed dimensions, estimated from both viscosity and light scattering results, led to the characteristic ratio, C_α, of 13.4 ± 0.7 at 31°C. Comparison of this value with those for other polystyrene derivatives shows that the characteristic ratio increases with the bulkiness of the side-group due to the steric effect.     

Hydrodynamic thickness and deformational properties of adsorption layers of poly(ethyleneoxides)

From the measurements of surface potentials of quartz capillaries before and after adsorption of poly(ethylene oxides) (PEO) of various molecular mass, an assessment of the equilibrium hydrodynamic thickness of the adsorption layers has been obtained. The results have been compared with those of independent measurements of . The flow of the polymer solution under increasing pressure drops at the ends of a capillary, which causes the corresponding shear stress () on the surface of adsorbed PEO layers, results in the deformation of the latter, which manifests itself in decreasing 5. The values decrease by several times when the shear stress rises to 2×10₂ N m^–2. Such values of have been obtained using thin capillaries (r = 5÷6 mm) and by application of the capillary electrokinetic method with pressure drops up to 5÷6 MPa.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 31–37, January, 1994.     

Protonated member of poly(diallylammonium) family: Hydrodynamic and conformational properties

Secondary polyamine in protonated salt form – poly(diallylammonium trifluoro-acetate) is characterized as representative of polymer series based on N,N-diallyl-ammonium. Its hydrodynamic behavior in 1 M NaCl has been compared with the other series members – quaternary poly(diallyldimethylammonium chloride) and tertiary poly(diallylmethylammonium trifluoroacetate). It was shown that these polymers belong to semirigid class whose Kuhn segment length ～4?nm just slightly depends on chemical structure at high ionic strength. As specific for secondary polyamine, the sensitivity to proton equilibrium in solution and counter ion type was detected resulting in great difference of its Mark–Kuhn–Houwink equations from the quaternary analogue at the same conditions.     

Hydrodynamic properties of rigid pyridine-containing poly(phenylene) dendrimers in solutions

The hydrodynamic properties of pyridine-containing polyphenylene dendrimers of the third and fourth generations in chloroform are studied by photon correlation spectroscopy and viscometry. It has been demonstrated that the hydrodynamic characteristics of these macromolecules in dilute solutions are similar to those of nondraining spheres. The hydrodynamic radius of these dendrimers is shown to be proportional to their molecular mass to a power of 1/3. It has been established that the macromolecules of the dendrimers under examination in solutions conserve the conformation and size over a wide temperature range. The detailed analysis of hydrodynamic data allowed a conclusion concerning an extremely low content of the polymer inside the equivalent sphere for the above dendrimers in solutions. The compounds of interest may be referred to as rigid dendritic systems.     

Enzymatic synthesis and characterization of a water-soluble, conducting poly(o-toluidine)

An enzymatic method for the synthesis of a water-soluble, conducting poly(o-toluidine) (POT) in the presence of sulfonated polystyrene (SPS) is presented. The enzyme horseradish peroxidase was used to polymerize o-toluidine to form a water-soluble, conducting POT/SPS complex, which exhibits moderate electrical conductivity. The synthesis is simple and the conditions are mild. The polymerization may be carried out at room temperature in pH 4.3 buffered aqueous solution with stoichiometric amount of monomer, SPS, hydrogen peroxide and catalytic amount of enzyme. The UV-Vis absorption spectra of the products display a distinct absorption peak at 740 nm at pH 4.3 that indicates the formation of the conducting, emeraldine salt form of POT. The structure and electrochemical behavior of the polymer was investigated with FT-IR and cyclic voltammetry method.     

Synthesis of poly(o-phenylenediamine) hollow spheres and nanofibers using different oxidizing agents

Poly(o-phenylenediamine) (PoPD) hollow spheres (ca. 800 nm in outer diameter) were synthesized by a simple solution route using ammonium persulfate (APS) as the oxidizing agent, whereas PoPD nanofibers (0.5-2 μm in width and more than 100 μm in length) and gold nanoparticles (200-500 nm) were obtained when changing the oxidizing agent of APS to chlorauric acid (HAuCl₄). The chemical structures of PoPD hollow spheres and nanofibers were characterized by FTIR and XRD spectra. When using HAuCl₄ as the oxidizing agent, the products of PoPD nanofibers and gold nanoparticles could be separated by chemical methods. The monomer droplets were proposed to act as template to the formation of polymer hollow spheres while the oriented growth of polymer nanofibers might be catalyzed by gold nanoparticles.     

Dipole moments of (styrene-p-chlorostyrene) triblock copolymers in solutions

(Styrene-p-chlorostyrene) triblock copolymers of the ABA and BAB types (A—polystyrene; B—poly-p-chlorostyrene) were prepared by anionic polymerization and their conformational behaviours in solutions were studied from measurements of the dipole moments. Two solvents, toluene and cumene, were used for the study; toluene is a good solvent for both polystyrene and poly-p-chlorostyrene whereas cumene is a selective solvent, good for polystyrene but poor for poly-p-chlorostyrene. It was found that the dipole moments of the block copolymers measured in toluene are the same for the ABA and BAB copolymers; in cumene however the dipole moment of the BAB copolymer is smaller than that of the ABA copolymer. The results give an additional support to our previous conclusion that the conformation of the block copolymers in a good solvent such as toluene could be approximated with a pseudo-random coil form; in a selective solvent, however, some anomalies take place in the conformation of the block copolymers, as deduced from intrinsic viscosity, osmotic pressure and light scattering measurements.     

Effects of bond-angle inversion on the statistical properties of poly(dimethylsiloxane)

Evidence of only a low barrier to inversion in Si? O? Si sequences could be important with regard to the interpretation of the statistical properties of silicone polymers. The effects are estimated for the temperature coefficients of the unperturbed dimensions, dipole moments, and optical-configuration parameter for poly(dimethylsiloxane).     

Kinetics of the dissociation and cis-trans isomerization of o,o'-azodioxytoluene (dimeric o-nitrosotoluene)

The dimer-monomer reactions were investigated for the system cis and transo,o'-azodioxytoluene-o-nitrosotoluene in acetonitrile solvent. For the reaction cis dimer-monomer the following thermodynamic and activation parameters have been derived: ΔH°=58.5±2.5 kJ mole^?1, ΔS°=206.2±3.8 J mole^?1 K^?1, ΔH^≠=63.6±3.3 kJ mole^?1, ΔS^≠=6.3±0.3 J mole^?1 K^?1. The corresponding values for the reaction trans dimer-monomer are: ΔH°=45.6±2.1 kJ mole^?1, ΔS°=162.7±7.1 J mole^?1 K^?1, ΔH^≠=80.8±2.9 kj mole^?1, ΔS^≠=-13.4±0.8 mole^?1 K^?1. There is no evidence of a direct cis-trans isomerization (i.e. a reaction not proceeding via the monomer). NMR and various perturbation techniques monitoring the visible absorption of the monomer were employed.     

Hydrodynamic properties and conformation of poly(3‐hexylthiophene) in dilute solutions

Conducting polymers demonstrate low solubility in organic solvents. Introducing aliphatic substituents into polymer chains improves their solubility, but may also lead to changes in conformational characteristics of macromolecules. In the present work, the studies of hydrodynamic properties and conformational characteristics of comb‐shaped poly(3‐hexylthiophene) with aliphatic side substituents were carried out in chloroform solutions. Conformational analysis of the studied macromolecules was performed for the first time using homologous series with a wide range of molecular weights of the polymers in dilute solutions. The hydrodynamic properties of these macromolecules were interpreted using the worm‐like spherocylinder model and the straight spherocylinder model. The projection of the monomer unit in the direction of the main polymer chain λ = 0.37 nm was determined experimentally. The following parameters of poly(3‐hexylthiophene) were characterized and quantified: equilibrium rigidity (Kuhn segment length) А = 6.7 nm and hydrodynamic diameter of a polymer chain d = 0.6 nm. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 875–883     

Hydrodynamic, electrooptical, and conformational properties of fullerene-containing poly(2-vinylpyridines) in solutions

For C₆₀ fullerene-containing poly(2-vinylpyridines) synthesized by anionic polymerization, the molecular mass and hydrodynamic size of macromolecules in solutions have been determined by molecular hydrodynamics (translational diffusion and viscometry) and electrooptics in dilute benzene and THF solutions. Under the same conditions in the molecular mass range (9.8–123) × 10³, the hydrodynamic behavior of linear poly(2-vinylpyridines) and their molecular-mass dependences have been examined and the conformational characteristics of macromolecules have been established. The branching of macromolecules has been characterized by comparing the properties of star-shaped fullerene-containing and linear poly(2-vinylpyridines). With consideration of the hydrodynamic data interpreted within the framework of regular star model, it is inferred that on average three to four linear polymer chains with a molecular mass of (8 ± 3) × 10³ for each chain are attached to a fullerene core of C₆₀ in molecules of fullerene-containing poly(2-vinylpyridines). The specific Kerr constant of fullerene-containing poly(2-vinylpyridines) in dilute benzene solution is ?(14 ± 1) × 10^?12 cm⁵/[g (300 V)²]. As evidenced by the electrooptical data, the incorporation of fullerene into the polymer weakens self-association of macromolecules in solution.     

Microwave spectrum of p-chlorostyrene

The microwave spectrum of p-chlorostyrene has been studied in the frequency region 18.0–26.5 GHz. Rotational transitions of the ground state, the first two torsionally excited states and two other vibrational states of the ³⁵Cl isotopic species have been identified. The molecule was found to be planar in the ground state. From intensity measurements, the frequency of the first torsional transition has been estimated to be 35 ± 15 cm^?1.     

Unperturbed dimensions of poly(9-vinyladenine)

The effect of base stacking interactions on the conformation of poly(9-vinyladenine) (PVAd) was investigated by osmometry, intrinsic viscosity, and light-scattering measurements. At neutral pH, ideal solution behavior (θ conditions) for this polymer was observed at 26 and 40°C. Intrinsic viscosity measurements revealed a conformational transition on heating from 26 to 40°C, while the ultraviolet absorbance of the solution was insensitive to the change. The transition was accompanied by an inversion in sign of the entropy parameter from negative to positive and an increase in the partial specific volume. At 40°, the variation of intrinsic viscosity with molecular weight corresponded to a random coil conformation, but the characteristic ratio, r?₀²/nl² = 8.6 ± 0.2 indicated that the unperturbed dimensions were smaller than usually observed for comparable vinyl polymers. At 26°, a rare macromolecular phenomenon was found, the intrinsic viscosity–molecular weight relation and the estimated r?₀²/nl² of 6.0–6.8 suggested that the PVAd was in a very highly compacted coil conformation, approaching a semirigid sphere. It is proposed that this effect be named the introversion phenomenon. Unlike polyadenylic acid, whose unperturbed dimensions increase with decreasing temperature due to nearest-neighbor base stacking, the results reported here suggest that both nearest-neighbor and long-range intramolecular base stacking occur in PVAd. The different stereochemical arrangements of bases in PVAd and Poly A are probably responsible for the opposite behavior observed.     

Unperturbed dimensions of poly(ethylene oxide)

The intrinsic viscosities of fractions of poly(ethylene oxide) in the molecular weight range 1.5 × 10³ to 10⁶ have been measured at 25°C in benzene, carbon tetrachloride, and acetone; at 35°C in 0.45M aqueous potassium sulfate; and at 50°C in methyl isobutyl ketone and diethylene glycol diethyl ether. The latter three are practically theta solvents. The value of (r₀² /M)^1/2 for poly(ethylene oxide) is calculated to be 0.84 Å from the molecular weights of the high molecular weight fractions, and their intrinsic viscosities in the theta solvents and acetone. Erroneous values result if the usual methods of determination are applied to the data obtained for the low molecular weight (<10⁴) fractions or to the intrinsic viscosities in the very good solvents, benzene and carbon tetrachloride.     

Comparative studies of chemically synthesized polyaniline and poly(o-toluidine) doped with p-toluene sulphonic acid

Polyaniline and poly(o-toluidine) doped with p-toluene sulphonic acid (p-TSA) were synthesized by in situ chemical polymerization method using ammonium per sulphate as an oxidizing agent. This is a novel polymerization process for the direct synthesis of emeraldine salt phase of the polymer. The polymers were characterized by using UV-Vis and FT-IR spectroscopy, SEM, elemental analyzer, TGA/DSC and conductivity measurements. Thermal analysis shows that poly(o-toluidine) is less thermally stable compared to polyaniline. The less conductivity in poly(o-toluidine) is due to the cumulative steric as well as electronic effect of the bulky methyl substituent present on the benzene ring. High temperature conductivity measurements show ‘thermal activated behavior’.     

In situ synthesis of copper nanoparticles and poly(o-toluidine): A metal-polymer composite material

We report here a novel in situ synthetic method for the preparation of poly(o-toluidine) and copper nanoparticle composite material. In this experiment, o-toluidine and cupric sulfate were used as the precursor; during the reaction o-toluidine was oxidized and forms poly(o-toluidine), while on the other hand cupric sulfate gets reduced and forms copper nanoparticle. IR, UV-vis and Raman spectra provide the information on the structure of the polymer. The TEM and SEM show the size of the nanoparticles and the morphology of the polymer, respectively.     

Estimating the thickness of hydrated ultrathin poly(o-phenylenediamine) film by atomic force microscopy

A novel method to measure ultrathin poly(o-phenylenediamine) (PPD) film electropolymerized on gold electrode in liquid was developed. It is based on the force versus distance curve (force curve) of atomic force microscopy (AFM). When 1-0.25 μm/s was chosen as the rising rate of the scanner, and 50% of the confidence interval (CI) as the qualifying threshold value, the thickness of the hydrated polymer film could be calculated. This result was compared with one obtained from an AFM image. A step-like electrode fabricated by a photolithographic process was used. The height difference of the electrode before and after the PPD coating was imaged in liquid, and then the real thickness, 19.6±5.2 nm, was obtained. The sample was also measured by estimating the transition range of the force curve of hydrated PPD film, and the thickness of the hydrated PPD film was determined to be 19.3±8.2 nm. However, the results calculated by integrating the electropolymerized charge for the oxidation process of o-phenylenediamine (o-PD) was only one-third as large as it was when using the two previously described methods. This indicated that the structure of hydrated PPD film might have been swollen.     

Unperturbed dimensions of isotactic poly(tert-butylethylene oxide)

The root-mean-square end-to-end distances of isotactic poly(tert-butylethylene oxide) fractions were determined in xylene at 80°C from intrinsic viscosity measurements and in o-dichlorobenzene at 80 and 100°C by light scattering. The characteristic dimension (〈L²〉₀/M)^1/2 was 1.04 × 10^?8 cm in xylene and 0.9 and 0.7 × 10^?8 cm in o-dichlorobenzene at 80 and 100°C, respectively. The value in xylene corresponds to a C_∞ of 15.9. This observation and the large negative temperature coefficient of (〈L²〉₀/M)^1/2 suggest that poly(tert-butylethylene oxide) exists in a helical block conformation under these experimental conditions. This conclusion is in agreement with earlier reported NMR measurements.     

An Unusual Organic-Inorganic Chain-like Hybrid Complex [(CuCl)2(o-phen)]∞ (o-phen=o-phenanthroline)

A novel organic-inorganic hybrid complex [(CuCl)₂(o-phen)]_∞ 1 (o-phen=o-phenanthroline) has been hydrothermally synthesized and structurally characterized by elemental analyses, XPS spectrum, TG analysis, and single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system, space group P2₁/n, a=3.7285(7) Å, b=19.603(4) Å, c=16.757(3) Å, β=95.83(3)°, V=1218.4(4) ų, Z=4, λ(MoKα)=0.71073 Å (R(F)=0.0643 for 2559 reflections). Data were collected on an R-axis RAPID diffractometer at 293 K in the range of 1.60<θ<27.48°. The title compound exhibits a one-dimensional chain-like scaffolding constructed by the unusual [Cu₃Cl₃] hexagon motifs by sharing opposite edges. Only Cu(1) sites of the [Cu₃Cl₃] hexagon are coordinated with N donors of o-phen groups. Furthermore, the three-dimensional supermolecular architecture is formed by C-H…Cl hydrogen bonds between o-phen groups and CuCl chains.