ISSN:0021-2148    

DOI:10.1002/ijch.197300013

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

ISSN:0021-2148    

DOI:10.1002/ijch.197300014

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractComputer simulation of cooperative, many particle systems (eg. real gas, Ising lattice) encounters a difficulty inherent to the ensemble theory. Under given conditions, the typical configurations constitute a vanishingly small fraction of all possible particle arrangements. Moreover, near to certain phase transitions, the typical configurations abruptly acquire pronounced long range order. Hence a computer method (like Metropolis Monte‐Carlo), which is not explicitly oriented towards discovery of such extremely rare arrangements, will almost certainly become inadequate. An attempt is made to formulate quantitatively these elementary observations, with the view of deriving a unified search for methods, that will enable to simulate the emergence of long range order in random system

ISSN:0021-2148    

DOI:10.1002/ijch.197300015

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe expressions for force versus length and the probability distribution of length for a chain composed of links that can interconvert among several conformations are derived. The theoretical values of average chain dimensions and thermodynamic functions are compared with those of a chain of uniform links. High and low force limits are considered.

ISSN:0021-2148    

DOI:10.1002/ijch.197300016

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe conformational space accessible to the N‐acetyl N′‐methyl amides of the 20 naturally occurring amino acids has been explored extensively with the aid of empirical energy functions, and many minima have been located. The statistical weights for all minima with energy ≤ 3 kcal above the lowest for each residue have been calculated. In numerous cases, the conformation of lowest energy does not possess the highest statistical weight, thereby emphasizing the importance of considering the conformational librations when comparing theoretical and experimental results. The calculated minimum‐energy conformations, as well as those of highest statistical weight, are for the most part in good agreement with experimental results from studies of these compounds in solution and in the crystall

ISSN:0021-2148    

DOI:10.1002/ijch.197300017

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe adsorption of compact macromolecules from solution is considered. A model is developed which permits direct comparison of present results with those for linear flexible structures. It is shown that, under equivalent conditions, size, not conformation, is the determining factor for the amount adsorbed. Size, not conformation, moreover, is responsible for the widespread plateau which is observed as a function of bulk concentration.

ISSN:0021-2148    

DOI:10.1002/ijch.197300018

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractA statistical thermodynamical method is presented for calculation of thermodynamic properties of ionic systems. The method has a straightforward formalism for taking into account a variety of physical factors, e.g., making allowance for different finite volumes of different ionic species, treatment of neutral species as thermodynamic components (rather than merely regarding them as a dielectric medium), consideration of dependences of the dielectric constant on solvent composition (in the case of a mixed solvent) and on electric field strength, nonionic interactions, etc. The method is based on an approach of J. L. Jackson [1] whereby a fluctuation state of the system is characterized in terms of a set of functions for the spatial variations of concentrations of the various species. For such a state an appropriate Boltzmann factor is defined and a calculation of a thermodynamic property of the system requires integrations of this factor overfunction spaces.Two simple applications of the method are worked out by way of illustration and other, more refined, applications are pointed out.

ISSN:0021-2148    

DOI:10.1002/ijch.197300019

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe possible dependence of the “unperturbed dimensions” of ionizable polymer chains on the charge density along the macromolecular chain is discussed in the light of theoretical studies and of experimental evidence. Some experiments on the behavior of dicarboxylic acids are suggested which would provide information useful in the interpretation of the behavior of polycarboxylic acids. A kinetic study of intramolecular reactions of polyions carrying small numbers of randomly spaced reactive and catalytic groups is proposed as a means to characterize chain flexibility. Finally, the advantages are pointed out which result from supplementing data on the ionization equilibrium of polymeric acids with calorimetric d

ISSN:0021-2148    

DOI:10.1002/ijch.197300020

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractIntrinsic viscosities [η], sedimentation coefficients s, radii of gyration Rgand second virial coefficients A2, refractive index increments and apparent specific volumes were determined in aqueous solution in theta solvents and over a wide range of concentrations msof a supporting electrolyte KCl, for five samples of potassium polystyrene sulfonate prepared by sulfonation of narrow molecular weight distribution polystyrenes. Coil expansion coefficientsαas well as the Flory coefficient Φ relating [η] to coil dimensions were evaluated. Following a theory of Alexandrowicz,α2was found to be a linear function of M1/4m−1/3S; Φ appears to decrease with increase inα.The low values of Φ, characteristic for polyelectrolyte solutions, are consistent with the value determined for the Mandelkern‐Flory paramete

ISSN:0021-2148    

DOI:10.1002/ijch.197300021

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY

摘要:

AbstractThe viscosities and densities of solutions of nine alkali halides (lithium, sodium, potassium, rubidium, and cesium chlorides; sodium fluoride, bromide and iodide; cesium iodide) and four quaternary ammonium bromides (tetramethyl, tetraethyl, tetra‐n‐propyl and tetra‐n‐butyl) have been measured over the concentration range 0.05–0.25 N in dioxane‐water mixtures containing 0–63 weight % dioxane. The Jones‐DoleB‐coefficient for the alkali halides increases as the dioxane fraction increases, to values much larger than those corresponding to the Einstein volume effect, suggesting a selective solvation of the cations. With increasing dioxane fraction, theB‐coefficients for the quaternary salts tend towards the theoretical values calculated from the known crystallographic

ISSN:0021-2148    

DOI:10.1002/ijch.197300022

出版商:WILEY‐VCH Verlag    

年代:1973

数据来源: WILEY