Stability constants and thermodynamic parameters of some intermacromolecular complexes in relation to their specific interaction forces

Summary Intermacromolecular complexes of poly (acrylic acid) (PAA) with poly (ethylene oxide) (PEO), poly (ethylene imine) (PEI) and poly (vinyl pyrrolidon) (PVP) were prepared. The stability constants and thermodynamic parameters (e.g. ΔH⁰ and ΔS⁰) of these complexes were determined at several temperatures. The enthalpy and entropy changes of the systems with temperature have been interpreted in terms of various mode of interaction between the components and compared with each other.     

Stability constants and thermodynamic parameters of some intermacromolecular complexes of acrylic copolymers and poly(vinyl pyrrolidone)

Stability constants and thermodynamic parameters (e.g. ΔH⁰ and Δ⁰) have been determined for intermacromolecular complexes of methacrylic acid-methacrylamide and acrylic acid-acrylamide copolymers with poly(vinyl pyrrolidone) (PVP). The presence of nonionic units in the copolymers greatly enhances the stability of the complexes with PVP. The enthalpy and entropy changes of the systems with temperature have been interpreted in terms of various modes of interaction between the components.     

Investigation on thermodynamic parameters and stability of some polyelectrolyte complexes with respect to ionic strength of the medium

The effect of ionic strength of the medium on stability constant and related thermodynamic parameters (e.g. ΔH⁰ and ΔS⁰) has been studied for a typical polyelectrolyte interpolymer complexes e.g. poly (acrylic acid), poly (ethylene imine) in aqueous solution using various inorganic salts. Stability constant K, and related thermodynamic parameters have been calculated and compared for interpolymer complex in different complexation medium using Osada’s method. The comparative study indicated considerable difference in the values of these parameters which has been explained on the basis of the relative strength of electrostatic interaction in different medium.     

Crystal structure and thermodynamic parameters of Nylon-1010

WAXD, SAXS, FTIR, DSC and density techniques have been used to investigate the crystal structure, crystal density ρ_c, amorphous density p_a equilibrium heat of fusion δH°_m and equilibrium melting temperature T°_m. By extrapolating the straight lines in the FTIR absorbance against density plot to zero intensity. ρ_c and ρ_a were estimated to be 1.098 and 1.003 g/cm³ respectively. The ρ_c obtained was too low in value. From X-ray diffraction patterns of uniaxially oriented fibres, the crystal structure of Nylon-1010 was determined. The Nylon-1010 crystallized in the triclinic system, with lattice dimensions: a = 4.9 Å, b = 5.4 Å, c = 27.8 Å, α = 49°, β = 77°, γ = 63.5°. The unit cell contained one monomeric unit, the space group was P1 , and the correct value of ρ_c was 1.135 g/cm³. The degree of crystallinity of the polymer was determined as about 60% (at RT) using Ruland's method. SAXS has been used to investigate the crystalline lamellar thickness, long period, transition zone, the specific inner surface and the electron density difference between the crystalline and amorphous regions for Nylon-1010. The analysis of data was based upon a one-dimensional electron-density correlation function. δ H°_m was estimated to be 244.0 J/g by extrapolation of δH°_m in the plot of heat of fusion against specific volume of semicrystalline specimens to the completely crystalline condition (V = 1/ρ_c). Owing to the ease of recrystallization of melt-crystallized Nylon-1010 specimens, the well-known Hoffman's T_m-T_c method failed in determining T°_m and a Kamide double extrapolation method was adopted. The T°_m value so obtained was 487 K.     

新型杯芳烃的合成应用及选择性络合作用

本文简要介绍了杯芳烃的产生、应用及结构特征,重点介绍了:(1)新型杯芳烃的合成;(2)新型杯芳烃衍生物的合成及选择性识别作用;(3)新型杯芳烃的合成及应用。     

Effect of some selective aromatic cosolutes on the main thermodynamic parameters of aqueous poly(n‐vinyl‐2‐pyrrolidone) solutions

Cloud‐point curves and theta temperatures have been determined for aqueous solutions of poly(N‐vinyl‐2‐pyrrolidone) at several concentrations for a variety of aromatic additives (benzoic acid, o‐ and p‐hydroxy benzoic acid, aniline, o‐ and p‐hydroxy aniline). The theta temperature of polymer is suppressed at lower temperatures depending on the chemical structure and the concentration of additives. The effectiveness, in decreasing order, of the cosolutes in reducing the temperature is: p‐hydroxy benzoic acid > o‐hydroxy benzoic acid > p‐hydroxy aniline > o‐hydroxy aniline ≈ benzoic acid > aniline. It is understood that changes in theta temperatures caused by the cosolute result from the changes taking place in the hydrophilic and hydrophobic interactions among polymer, solvent and polymer–solvent interactions from the added cosolute. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 507–510, 2000     

Evaluation of thermodynamic and hydrodynamic parameters of polymer molecules

Summary A numerical regression method, assisted by a least squares technique, is proposed to obtain thermodynamic and hydrodynamic parameters of polymer molecules via a direct comparison between experimental data and theoretical functions. This comparison is independent of the number of the experimental variables. The method also enables to decide if a selected set of theoretical equations fits satisfactorily the experimental results.     

Selective intermacromolecular complex formation between phenolic and nonionic polymers

The selective intermacromolecular complex formation between p-bromophenol-formaldehyde copolymer (PPF) and poly(vinyl pyrrolidone) (PVP) and poly(ethylene oxide) (PEO) has been investigated. PVP has been found to have greater ability for complex formation compared to PEO with respect to PPF. An open-chain mechanism has been proposed for the substitution reaction between PVP and PPF-PEO complex. The abnormal behaviour of viscosity curves has been interpreted on the basis of probable association between the nonionic polymers.     

Calculation of some thermodynamic characteristics of ε-caprolactam

Conclusions Using calculation methods based on the chemical structure of molecules, characteristic constants of -caprolactam which are missing from the literature have been calculated.On the basis of the principle of corresponding states, using characteristic constants, the thermodynamic characteristics of caprolactam have been refined and determined anew (pressure, heat of vaporization, and heat capacity) over a wide temperature range.Translated from Khimicheskie Volokna, No. 1, pp. 20–22, January–February, 1988.     

Regression of constrained parameters for nonlinear thermodynamic models

An algorithm based on variable Metric method has been applied to the determination of molecular thermodynamic model parameters from experimental data when any model need several constraints. Implementation of the method is illustrated in the reduction of multi-property equation of state data for the systems of argon, nitrogen and methane.     

Surface and thermodynamic parameters of sodium N-acyl sarcosinate surfactant solutions

Surface tension as a function of concentration and temperature was measured for solutions of N-acyl sarcosinates, RCON(CH₃)CH₂COONa. From the intersection points in the (γ-log c) curves, the critical micelle concentration (CMC) was determined at 20, 35, 50, and 65°C. Structural effects on the CMC, maximum surface excess, and the minimum area per molecule at the aqueous solution/air interface are discussed. The free energy, enthalpy, and entropy of micellization and adsorption of surfactant solutions also were investigated.     

Thermal Stability of some polyphosphonylureas

Polyphosphonylureas were prepared from the condensation of phenylphosphonic diisocynate with secondary and primary diamines employing the interfacial technique. The thermal properties of the products were studied by differential scanning calorimetry and thermal gravimetric analysis. In air the products undergo thermal oxidative degradation at temperatures greater than 300°C. The products undergo identical thermal degradation at temperatures less than 300°C in both air and N₂. The products show significantly better thermal stability than their carbon counterparts.     

Temperature dependence of some thermodynamic functions for amorphous and semi-crystalline polymers

The temperature dependence of some heat-capacity related functions is evaluated on the basis of experimental data, and a further elaboration is given for polyethylene.     

Dielectric and thermodynamic behaviour of some monohydric alcohols in dioxane and cyclohexane

The dielectric and thermodynamic behaviour of some monohydric alcohols in their dioxane or cyclohexane solutions is investigated in the microwave frequency region as a function of concentration and temperature. It has been found that the relaxation time decreases monotonically on the addition of dioxane. This behaviour is different from that found previously by similar measurements on alcohol-heptane solutions and in the present investigation on ethanokyclohexane solutions. The results are discussed in relation to the chemical structure. Computation of the experimental data by a polynomial curve fitting programme has resulted in analytical relationships between the relaxation time variation and the concentration.     

Metal-containing intermacromolecular complexes: Electrochemical and viscometric studies in DMF-methanol mixture

Summary Multicomponent intermacromolecular complexes have been prepared from some typical phenolic copolymers with a non-ionic polymer (e.g. PVP), and a polyelectrolyte (e.g. PAA). Some transition metal ions (e.g. Cu(II) and Ni (II)) have been incorporated in the complex through its unreacted co-ordinating groups. The formation of these complexes has been studied by several techniques, such as viscometry, conductometry, potentiometry, IR and UV spectrophotometry. A scheme has been presented to explain the mode of interaction of the various components.     

Natural dye–surfactant interactions: thermodynamic and surface parameters

The interaction of two Indian natural dyes, namely madder (Rubia cordifolia) and mallow (Punica granatum), with cationic surfactant cetyl trimethyl ammonium bromide and anionic surfactant sodium lauryl sulphate, has been studied. Spectrophotometric data showed a strong interaction between the natural dyes and the surfactants. The critical micelle concentration of the surfactants, determined by measurement of specific conductance and surface tension, was found to decrease on the addition of natural dyes in an aqueous solution of surfactants. The thermodynamic and surface parameters for the interaction have been evaluated.     

Characterization of composite membranes by their non-equilibrium thermodynamic transport parameters

Composite reverse osmosis membranes were prepared by interfacially polymerizing aromatic polyamide discriminating layers on the inside surface of microporous polyethersulfone hollow fibers and on the surface of flat sheet polysulfone ultrafilters. The salt rejection and flux of these membranes were measured at various feed pressures. From these measurements, the membrane reflection coefficients, salt permeances and hydraulic permeances were estimated. Neither the polysulfone ultrafilters nor the microporous polyethersulfone hollow fibers possessed any inherent salt rejecting capability. Both had a hydraulic permeance at least two orders of magnitude greater than that of the respective composite membranes. Consequently, it was concluded that the estimated transport parameters for both composite membranes were characteristics exclusively of thier polyamide discriminating layers. Comparison of these transport parameters generated insight into structural and functional aspects of the membrane that could not be visualized by scanning electron microscopy.