Synthesis and solution properties of amphiphilic cycloterpolymers of 1,1-diallyl-4-formylpiperizinium chloride, diallyloctadecylammonium chloride and sulfur dioxide

The cycloterpolymerizations of hydrophilic monomer (1,1-diallyl-4-formylpiperizinium chloride) with hydrophobic monomer (diallyloctadecylammonium chloride) and sulfur dioxide in dimethyl sulfoxide using azobisisobutyronitrile (AIBN) as the initiator afforded a series of water-soluble monocationic polyelectrolytes (MCPEs) in well over 90% yields. Acidic (HCl) hydrolysis of the N-formyl groups in MCPEs to NH₂⁺Cl⁻ groups gave the dicationic polyelectrolytes (DCPEs), which on treatment with one equivalent of NaOH furnished the basic cationic polyelectrolytes (BCPEs) containing basic as well as quaternary nitrogens. The solution properties of the resultant series of interconverting polyelectrolytes (MCPE → DCPE ↔ BCPE) were investigated by viscometric techniques. The polymer concentration C∗_HA of 0.2 g/dL was required for the manifestation of hydrophobic associations in a MCPE containing 4.5 mol% octadecyl pendents. The DCPEs exhibited sharp increase in viscosity in salt (NaCl)-added solution as compared to salt-free water. The pH-responsive BCPE is shown to demonstrate better associative properties in the absence of HCl; upon addition of HCl, the charge density increases in the polymer chains thereby resulting in increased electrostatic repulsions and decreased associations. Polymer-surfactant interactions were investigated using cationic surfactant cetyltrimethylammonium chloride (CTAC); tremendous increase in the viscosity values of the DCPE was observed in the presence of the surfactant.     

Densities,Apparent Molar Volumes and Viscosities of Concentrated Aqueous NaNO<Subscript>3</Subscript> Solutions at Temperatures from 298 to 607 K and at Pressures up to 30 MPa

Densities of four (2.124, 2.953, 5.015 and 6.271 mol-kg⁻¹) and viscosities of eight (0.265, 0.503, 0.665, 1.412, 2.106, 2.977, 5.015 and 6.271 mol-kg⁻¹) NaNO₃(aq) solutions have been measured with a constant-volume piezometer immersed in a precision liquid thermostat and using capillary flow techniques, respectively. Measurements were made at pressures up to 30 MPa. The temperature range was 298–607 K for the density measurements and 298–576 K for the viscosity measurements. The total uncertainty of density, viscosity, pressure, temperature and composition measurements were estimated to be less than 0.06%, 1.6%, 0.05%, 15 mK and 0.02%, respectively. The temperature, pressure and concentration dependence of density and viscosity of NaNO₃(aq) solutions were studied. The measured values of density and viscosity of NaNO₃(aq) were compared with data and correlations reported in the literature. Apparent molar volumes were derived using the measured density values. The viscosity data have been interpreted in terms of the extended Jones–Dole equation for strong electrolytes. The values of the viscosity A-, B-, D- and F-coefficients of the extended Jones–Dole equation for the relative viscosity (η/η₀) of NaNO₃(aq) solutions were evaluated as a function of temperature. The derived values of the viscosity A- and B-coefficients were compared with the results predicted by Falkenhagen–Dole theory of electrolyte solutions and calculated with the ionic B-coefficient data.     

Viscometric study of poly(sodium 2-acrylamido-2-methylpropanesulfonate) and two random copolymers

Effects of the polyanion synthesis conditions and composition on the viscometric behavior of poly(sodium 2-acrylamido-2-methylpropanesulfonate) (PAMPS) and two random copolymers, poly(sodium 2-acrylamido-2-methylpropanesulfonate-co-methylmethacrylate) (PAMPSMM) and poly(sodium 2-acrylamido-2-methylpropanesulfonate-co-tert-butylacrylamide) (PAMPSTBA), in a wide range of concentrations were reported in this paper. The experimental data obtained in salt-free aqueous solution were plotted in terms of the Fuoss and the Rao equations in order to obtain the intrinsic viscosity values. The C∗ values obtained as the reciprocal of the intrinsic viscosity were compared with the experimentally determined values and with those calculated according to the Odijk theory. An acceptable agreement between C∗ values obtained by different approaches was found for the PAMPS samples with high molar masses (0.83 × 10⁶-1.4 × 10⁶ g/mol). For the same charge density and the same concentration the reduced viscosity values were higher for PAMPSMM comparative with PAMPSTBA indicating a higher chain extension of the former copolymer.     

Polyelectrolyte complex formation between poly(diallyldimethyl-ammonium chloride) and copolymers of acrylamide and sodium-acrylate

 The interaction between oppositely charged polyelectrolytes, in this study poly(diallyldimethylammonium chloride) (PDADMAC) and copolymers of acrylamide and sodium-acrylate differing in their chain length and charge density parameter (ξ) was investigated in relation to the molar charge ratio of anionic to cationic charges (n ₋/n ₊). The molecular weights of the polyelectrolytes used were 2.9·10⁵g/mol for PDADMAC and for the polyacrylamide copolymers 14 ·10⁶g/mol as well as 5·10⁵g/mol obtained by ultrasonic degradation of the high molecular weight copolymers. The charge density parameters of the polyanions used (ξ ^PR ) varied between 0.14 and 0.64. Complexation between PDADMAC and high molecular weight polyanions leads mainly to macroscopic phase separation whereas the degraded polyanions and PDADMAC formed soluble complexes as well as stable dispersions, if charge excess was available. Precipitates and dispersions were characterized by several methods such as element analysis, thermogravimetry, pyrolysis-GC/MS, PEL titration, ζ-potential measurements, determination of turbidity, particle size measurements and determination of carbon content (TOC).  All precipitated complexes include about 20% water and are of 1:1 stoichiometry concerning ionic binding. Investigations of dispersions confirm 1:1 stoichiometry of complex particles stabilized by excess polyelectrolyte and soluble complexes. It was also found that the particle size can be varied via the charge density parameter of the polyanions used in the range of negative charge excess. Received: 21 June 2001 Accepted: 9 October 2001     

Thermophysical and thermoacoustical properties of benzaldehyde mixtures with ethylbenzene at 303.15, 308.15, and 313.15 K and a pressure of 0.1 MPa

Ultrasound velocity (u), density (ρ) and viscosity (η) measurements of benzaldehyde + ethylbenzene mixtures have been carried out at 303.15, 308.15, and 313.15 K. These values have been used to calculate the excess molar volume (V ^E), deviation in viscosity (δη), and deviation in isentropic compressibility (δβ_s), deviations in ultrasound velocity (δu), excess free volume (δV _f), excess intermolecular free length (δL _f) and excess Gibbs free energy of activation of viscous flow (δG ^E). McAllister’s three body interaction model is used for correlating kinematic viscosity of binary mixtures. The excess values were correlated using the Redlich-Kister polynomial equation to obtain their coefficients and standard deviations. The thermophysical properties under the study were fit to the Jouyban-Acree model. The observed variation of these parameters helps in understanding the nature of interactions in these mixtures. Further, theoretical values of the ultrasound speed were evaluated using theories and empirical relations.     

Excess Molar Volume and Viscosity of Isobutyric Acid + Water Binary Mixtures Near and Far Away from the Critical Temperature

The excess molar volume V^E, shear viscosity deviation Δη and excess Gibbs energy of activation ΔG^∗E of viscous flow have been investigated by using density (ρ) and shear viscosity (η) measurements for isobutyric acid + water (IBA+W) mixtures over the entire range of mole fractions at five different temperatures, both near and close to the critical temperature (2.055K ≤ (T−T_c)≤ 13.055K). The results were also fitted with the Redlich–Kister equation. This system exhibited very large negative values of V^E and very large positive values of Δη due to increased hydrogen bonding interactions and correlation length between unlike molecules in the critical region and to very large differences between the molar volumes of the pure components at low temperatures. The activation parameters ΔH^∗ and ΔS^∗ have been also calculated and show that the critical region has an important effect on the volumetric properties.     

Charge density effects in salt‐free polyelectrolyte solution rheology

Solution rheology of 2‐vinyl pyridine and N‐methyl‐2‐vinyl pyridinium chloride random copolymers in ethylene glycol was studied over wide ranges of concentration and effective charge. The fraction of quaternized monomers α and the fraction of monomers bearing an effective charge f of these copolymers were measured using counterion titration and dielectric spectroscopy, respectively. Ethylene glycol is a good solvent for neutral poly(2‐vinyl pyridine), with very few ionic impurities. The viscosity η and relaxation time τ of dilute and semidilute unentangled solutions exhibit the scaling with concentration and effective charge expected by the Dobrynin model. Reduced viscosity data are independent of concentration in dilute solution, giving an intrinsic viscosity that depends on effective charge, and the experimental data obey the Fuoss law in the semidilute unentangled regime. Scaling concentration with the overlap concentration (c/c*) reduces these data to common curves, and c* ～ f ^?12/7 as predicted by the Dobrynin model, where f is the fraction of monomers bearing an effective charge. While the overlap concentration depends strongly on effective charge until counterion condensation occurs, the entanglement concentration c_e is surprisingly insensitive to effective charge, indicating that entanglement effects are not understood using the Dobrynin model. The terminal modulus G = η/τ depends only on the number density of chains G = ckT/N for c* < c < c_e, and G ～ c^3/2 for c > c_e independent of the effective charge. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2001–2013, 2006     

Electrical conductivity of some cationic polysaccharides. I. Effects of polyelectrolyte concentration,charge density,substituent at the ionic group,and solvent polarity

Electrolytic conductivity behavior of some cationic polysaccharides in water, methanol, and the mixtures water/methanol is presented. The polyelectrolytes investigated contain quaternary ammonium salt groups, N‐alkyl‐N,N‐dimethyl‐2‐hydroxypropyleneammonium chloride, attached to a dextran backbone. This study considers the influences of polymer concentration (1 × 10^?6 < C < 1 × 10^?2 monomol L^?1) and the charge density (ξ = 0.48–3.17) modified either by changing charge distance (b) or dielectric constant of the solvent (ε) on polyion–counterion interaction in salt‐free solutions. Above the critical value, ξ_c = 1, the variation of the equivalent conductivity (Λ) as a function of concentration is typical for a polyelectrolyte behavior. The conductometric data in water were analyzed in terms of the Manning's counterion condensation theory. The presence of longer alkyl chains at quaternary N atoms was found to have a negligible influence on the Λ values. The results show that the decrease of the medium polarity results in the decrease of the number of free ions and, consequently, of the equivalent conductivity values. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3584–3590, 2005     

Behaviour of cationic polyelectrolytes upon binding of electrolytes: effects of polycation structure, counterions and nature of the solvent

 The effects of polycation structure, counterions and the nature of the solvent on the interaction between low-molecular-weight salts with some cationic polyelectrolytes in water and methanol were investigated. The polyelectrolytes used in this study were cationic polymers with quaternary nitrogen atoms in the backbone with or without a nonpolar side chain (polymer type PCA₅H₁, PCA₅D₁ and PCA₅) or tertiary amine nitrogen atoms in the main chain (polymer type PEGA). LiCl, NaCl, KCl, NaBr, NaI and Na₂SO₄ were used as low-molecular-weight salts. The interaction between polycations and salts was followed by viscometric and conductometric measurements. The study of the interaction of monovalent counterions with cationic polyelectrolytes emphasized an increase in the interaction with the decrease in the radius of the hydrated counterion, both for strong polycations and for weak polycations, suggesting that counterion binding is nonspecific. In the case of SO²⁻ ₄ anions, the Λ_m−c ^1/2 curve passes through a minimum at c _p values between 1 × 10⁻³ and 3 × 10⁻³ unit mol/l; this phenomenon can be explained by the maximum counterion interaction owing to the capacity of the polyvalent counterion to bind two charged groups by intra- or interchain bridges. The investigation of the influence of the polycation structure on the counterion binding indicated an increase in charged group–counterion interactions with a decrease in the nonpolar chain length and an increase in the quaternary ammonium salt group content (charge density) in the chain. The polyelectrolyte with tertiary amine groups in the chain, PEGA, showed, on one hand, a cation adsorption order as K⁺>Na⁺>Li⁺ and, on the other hand, a stronger association between ions and PEGA chains in methanol than in water owing to the poorer solvating effect of methanol on the cations. Received: 20 February 2001 Accepted: 29 June 2001     

Density and viscosity of α-amino acids in aqueous solutions of cetyltrimethylammonium bromide

The densities and viscosities of aqueous solution of cetyltrimethylammonium bromide (0.01 mol kg⁻¹) (CTAB) and solutions of CTAB containing amino acids, viz., glycine, l-serine, and l-valine (0.01–0.05 mol kg⁻¹), were determined in the temperature range 298.15—313.15 K. Apparent molar volumes of the amino acids were calculated from the density and viscosity values. The calculated apparent molar volumes were used to calculate standard partial molar volumes (-V ₂⁰) and standard partial molar volumes of transfer of amino acids from water to an aqueous solution of CTAB. The viscosity values were used for the calculation of the viscosity coefficients A and B in the Jones—Dole equation. The linear dependences of -V ₂⁰ and B on the number of carbon atoms in the alkyl chains of the amino acids were found. The results obtained were used in analysis of hydrophilic-hydrophilic, hydrophilic-hydrophobic, and hydrophobic-hydrophobic interactions that occur during dissolution of amino acids in an aqueous solution of CTAB.     

The chain length dependence of self-diffusion in melts of polyethylene and polystyrene

The self-diffusion coefficients in melts of polyethylene fractions and polystyrene standards were measured by the NMR pulsed field gradient technique and compared with those measured by other techniques. The data agree very well if one takes into account the molar mass distribution of the samples and the free volume of the matrix. For molar masses much higher than the critical molar massM _c, reptation is confirmed,D M ^–2 holds. BelowM _e=M_c/2 the self-diffusion coefficients corrected for constant free volume show approximately the dependenceD M ^–1 confirming Rouse-like diffusion. This result was also obtained by investigating the self-diffusion of the molecules with different molar masses of a polyethylene fraction with a rather broad molar mass distribution aroundM _e andM _c, i. e. diffusion in a constant matrix. In the molar mass region betweenM _c and about 3 ·M _c the observed molar mass dependence of self-diffusion can be explained by tube formation. The constraint release model of Graessley seems to slightly overestimate the self-diffusion coefficients.     

Network formation and properties: Rate theory description of effects of ring formation on elastic shear modulus of RA2 + RB3 networks

The rate theory of RA₂+RB₃ polymerization has been developed to enable the concentrations of the smallest inelastic loops and the resulting reductions in elastic shear modulus at complete reaction to be evaluated. Reduction in modulus is expressed as M_c/M°_c, the effective molar mass of chains between elastically active junction points (M_c) relative to that for the perfect network for given reactants (M°_c). Calculations have been carried out for stoichiometric reaction mixtures and the concentration of loops is characterized by λ, a ring-forming parameter. λ = P_ab/C_Ao, where C_Ao is the initial concentration of A-groups and P_ab = (3/(2πvb²))^3/2/N_Av, with v the number of bonds in the chain forming the smallest loop, b the effective bond length of the chain, and N_Av Avogadro's number. P_ab is equal to the mutual concentration, assuming Gaussian statistics, of the A- and B-groups at the two ends of the linear sub-chain of v bonds. Loop formation increases as λ increases, that is, as the initial concentration of reactive groups (C_Ao) decreases, or, at constant C_Ao, as the molar mass of reactants (v) or their chain stiffness (b) decreases. Comparison with existing experimental data on two series of polyurethane networks formed from hexamethylene diisocyanate and two polyoxypropylene triols at different initial dilutions shows that the values of P_ab decrease with increases in initial dilution and molar mass of triol. The decrease with molar mass is entirely accounted for by changes in v and the variation with dilution shows that the approximation of counting only smallest loops improves as dilution increases.     

Experimental Study of the Effect of Temperature,Pressure and Concentration on the Viscosity of Aqueous NaBr Solutions

The viscosity of 10 (0.049, 0.205, 0.464, 0.564, 0.820, 1.105, 1.496, 2.007, 2.382, and 2.961 mol ċ kg⁻¹) binary aqueous NaBr solutions has been measured with a capillary-flow technique. Measurements were made at pressures up to 40 MPa. The range of temperature was 288–595 K. The total uncertainty of viscosity, pressure, temperature and composition measurements were estimated to be less than 1.6%, 0.05%, 15 mK, and 0.02%, respectively. The effect of temperature, pressure, and concentration on viscosity of binary aqueous NaBr solutions were studied. The measured values of the viscosity of NaBr(aq) were compared with data, predictions and correlations reported in the literature. The temperature and pressure coefficients of viscosity of NaBr(aq) were studied as a function of concentration and temperature. The viscosity data have been interpreted in terms of the extended Jones–Dole equation for the relative viscosity (η/η₀) to calculate accurately the values of viscosity A- and B-coefficients as a function of temperature. The derived values of the viscosity A- and B-coefficients were compared with the results predicted by the Falkenhagen–Dole theory of electrolyte solutions and calculated with the ionic B-coefficient data. The physical meaning parameters V and E in the absolute rate theory of the viscosity and hydrodynamic molar volume V k were calculated using the present experimental viscosity data. The TTG model has been used to compare predicted values of the viscosity of NaBr(aq) solutions with experimental values at high pressures.     

Excess properties and spectroscopic studies of binary system 1,4-butanediol + water at T = (293.15, 298.15, 303.15, 308.15, 313.15 and 318.15) K

Density and dynamic viscosity data were measured over the whole concentration range for the binary system 1,4-butanediol (1) + water (2) at T = (293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K as a function of composition under atmospheric pressure. Based on density and dynamic viscosity data, excess molar density (ρ^E), dynamic viscosity deviation (Δν) and excess molar volume (V_m^E) were calculated. From the dynamic viscosity data, excess Gibbs energies (ΔG*^E), Gibbs free energy of activation of viscous flow (ΔG*), enthalpy of activation for viscous flow (ΔH*) and entropy of activation for viscous flow (ΔS*) were also calculated. The ρ^E, V_m^E, Δν and ΔG*^E values were correlated by a Redlich?Kister-type function to obtain the coefficients and to estimate the standard deviations between the experimental and calculated quantities. Based on FTIR and UV spectral results, the intermolecular interaction of 1,4-butanediol with H₂O was discussed.     

Study of Micellar Behavior of SDS and CTAB in Aqueous Media Containing Furosemide—A Cardiovascular Drug

Sound velocity and density measurements of aqueous solutions of the anionic surfactant SDS (sodium dodecyl sulfate) and the cationic surfactant CTAB (cetyltrimethylammonium bromide) with the drug furosemide (0.002 and 0.02 mol⋅dm⁻³) have been carried out in the temperature range 20–40 °C. From these measurements, the compressibility coefficient (β), apparent molar volume (φ _v ) and apparent molar compressibility (φ _κ ) have been computed. From electrical conductivity measurements, the critical micelle concentrations (CMCs) of SDS and CTAB has been determined in the above aqueous furosemide solutions. From the CMC values as a function of temperature, various thermodynamic parameters have been evaluated: the standard enthalpy change (DH_m^o\Delta H_{\mathrm{m}}^{\mathrm{o}}), standard entropy change (DS_m^o\Delta S_{\mathrm{m}}^{\mathrm{o}}), and standard Gibbs energy change (DG_m^o\Delta G_{\mathrm{m}}^{\mathrm{o}}) for micellization. This work also included viscosity studies of aqueous solutions of SDS and CTAB with the drug in order to determine the relative viscosity (η _r). UV-Vis studies have also been carried for the ternary drug/surfactant/water system having SDS in the concentration range 0.002–0.014 mol⋅dm⁻³. All of these parameters are discussed in terms of drug–drug, drug–solvent and drug–surfactant interactions resulting from of various electrostatic and hydrophobic interactions.     

Molar volumes and viscosities of LiClO4 and LiBr in propylene carbonate + 1,2-dimethoxyethane mixed solvents at 298.15 K

The standard partial molar volumes, viscosity B-coefficients and activation free energies of lithium salts (LiClO₄ and LiBr) in propylene carbonate (PC) with 1,2-dimethoxyethane (DME) mixed solvents have been determined as a function of the mole fraction of DME at 298.15 K from precise density and viscosity measurements. The values studied are all positive and decrease monotonously with addition of DME in the PC, which indicates that nature of the solvents plays an important role. The effects are discussed in terms of preferential solvation and packing effect in the solvation shell and electrostriction. The differences between ClO₄⁻ and Br⁻ have also been discussed.     

Densities, viscosities, and ultrasonic velocity studies of binary mixtures of trichloromethane with methanol, ethanol, propan-1-ol, and butan-1-ol at T = (298.15 and 308.15) K

Densities, viscosities, and ultrasonic velocities of binary mixtures of trichloromethane with methanol, ethanol, propan-1-ol, and butan-1-ol have been measured over the entire range of composition, at (298.15 and 308.15) K and at atmospheric pressure. From the experimental values of density, viscosity, and ultrasonic velocity, the excess molar volumes (V^E), deviations in viscosity (Δη), and deviations in isentropic compressibility (Δκ_s) have been calculated. The excess molar volumes, deviations in viscosity and deviations in isentropic compressibility have been fitted to the Redlich-Kister polynomial equation. The Jouyban-Acree model is used to correlate the experimental values of density, viscosity, and ultrasonic velocity.     

Excess molar volumes,viscosity, refractive index,and Gibbs energy of activation of binary biodiesel + benzene,and biodiesel + toluene mixtures at 298.15 and 303.15 K

Excess molar volumes (V ^E), viscosities, refractive index, and Gibbs energies were evaluated for binary biodiesel + benzene and toluene mixtures at 298.15 and 303.15 K. The excess molar volumes V ^E were determined from density, while the excess Gibbs free energy of activation G*^E was calculated from viscosity deviation Δη. The excess molar volume (V ^E), viscosity deviation (Δη), and excess Gibbs energy of activation (G*^E) were fitted to the Redlich-Kister polynomial equation to derive binary coefficients and estimate the standard deviations between the experimental data and calculation results. All mixtures showed positive V ^E values obviously caused by increased physical interactions between biodiesel and the organic solvents.     

Determination of the net electric charge of a polyacrylamide molecule by Donnan potential measurements

The net electric chargez _pof a polyacrylamide molecule (Praestol, Mol. Wt. 3.4×10⁶) in aqueous solution was determined for two pH values (7.2 and 10.0) by measuring the Donnan e.m.f. as function of the solutions NaCl contentc (2.7 mM<c<74 mM). Taking into account a non-ideal behavior of the counterions (Na⁺) mobility, the numerical values ofz _pturned out to be 3100 and 5500 electric charge units for pH=7.2 and 10.0, respectively. A measurable contribution of the assumed non-ideal model for the Na⁺ ions is found forc<15 mM.     

Hydrophobic Interactions of Methylureas in Aqueous Solutions Estimated with Density, Molal Volume, Viscosity and Surface Tension from 293.15 to 303.15 K

Density (ρ), viscosity (η), and surface tension (γ) for 0.005–0.25 mol ⋅ kg⁻¹ solutions of urea, 1-methylurea, and 1,3-dimethylurea solutions have been measured at intervals of 0.005 mol ⋅ kg⁻¹. Apparent molal volume (V _o, cm³ ⋅ mol⁻¹) and intrinsic viscosity coefficients (B and D) are calculated from the ρ and η values, respectively. Primary data were regressed and extrapolated to zero concentration for the limiting density (ρ ⁰), apparent molal volume (V _φ ⁰), viscosity (η ⁰), and surface tension (γ ⁰) values for solute–solvent interactions. The –CH₃ (methyl) groups of N-methylureas weaken hydrophilic interactions and enhance hydrophobic interactions, and the values of the ρ ⁰ and V _φ ^o reflect the intermolecular forces due to electrostatic charge, whereas the η ⁰ and γ ⁰ values reflect the frictional and surface forces. The B values depict the size of hydrodynamic sphere due to heteromolecular forces whereas D shows the effect of concentration. The molar surface energy (ΔE _m/sur) for dropwise flow was calculated from the γ values and decreases with concentration and temperature, but increases with –CH₃ weakening of the hydrophilic interactions and strengthening the hydrophobic interactions.