On the Effect of Heterogeneity in Molecular Weight on the Sedimentation Equilibrium Second Virial Coefficient of Polymers in Good Solvents

1964 ◽  
Vol 68 (7) ◽  
pp. 1798-1800 ◽  
Author(s):  
Irwin H. Billick
Keyword(s):  
Molecular Weight ◽  
Virial Coefficient ◽  
Second Virial Coefficient ◽  
Sedimentation Equilibrium

scholarly journals Sedimentation-equilibrium and other physicochemical studies on the lysine-rich fraction of calf thymus histones

1968 ◽  
Vol 110 (2) ◽  
pp. 243-250 ◽  
Author(s):  
A. J. Haydon ◽  
A. R. Peacocke
Keyword(s):  
Molecular Weight ◽  
Virial Coefficient ◽  
Average Molecular Weight ◽  
Second Virial Coefficient ◽  
Apparent Molecular Weight ◽  
Optical Rotatory Dispersion ◽  
Sedimentation Equilibrium ◽  
Acid Extraction ◽  
Equilibrium Studies ◽  
Calf Thymus

1. The lysine-rich fraction (Ia+Ib, or f1) of calf thymus histones was isolated as the sulphate by acid extraction. 2. Sedimentation-equilibrium measurements with interference optics showed that this fraction was monodisperse with a molecular weight of 19500±2000. 3. The ‘apparent molecular weight’ calculated from the sedimentation-equilibrium studies varied markedly with concentration. The large second virial coefficient implied by such variation was attributed to the very high charge/mass ratio of this relatively small protein. Estimates of the charge were made from the values of this virial coefficient. 4. The very large value of the virial coefficient explains anomalies in the earlier reports of the molecular weight of this histone and also why the z-average molecular weight can appear to be lower than the weight-average molecular weight. 5. The differences of the specific refractive increments, and the partial specific volumes, between dialysed and undialysed solutions of this histone fraction could also be attributed to its high molecular charge, which was estimated from these differences and agreed, within the expected limits, with the value deduced from the second virial coefficient. 6. Sedimentation-velocity measurements combined with the known molecular weight imply that lysine-rich histone has a high frictional ratio and an extended shape. Optical-rotatory-dispersion measurements indicated that it had a low helical content.

Partitioning of charged and neutral dextran-dye derivatives in biphasic cellulose nanocrystal suspensions

2008 ◽  
Vol 86 (6) ◽  
pp. 503-511 ◽  
Author(s):  
Stephanie Beck-Candanedo ◽  
David Viet ◽  
Derek G Gray
Keyword(s):  
Molecular Weight ◽  
Partition Coefficient ◽  
Cellulose Nanocrystals ◽  
Partition Coefficients ◽  
Virial Coefficient ◽  
Total Concentration ◽  
Second Virial Coefficient ◽  
Fluorescein Isothiocyanate ◽  
Blue Dextran ◽  
Molecular Weights

The partitioning behaviour of dye-labeled dextrans of high molecular weight in aqueous suspensions of native cellulose nanocrystals was studied. Cellulose concentrations lie in the isotropic–nematic coexistence region. Blue dextrans of various molecular weights and degrees of substitution of dye molecules (anionic Cibacron blue 3G-A) were investigated. Increasing the total concentration of blue dextran and degree of dye substitution led to increasing partition coefficients. Increasing dextran molecular weight resulted in higher partition coefficients, in agreement with theory. Partition coefficients were larger than predicted theoretically using a second virial coefficient approximation. Electrostatic and entropic contributions to the partition coefficient of blue dextran are discussed. Dextrans labeled with neutral fluorescein isothiocyanate did not partition preferentially in this system.Key words: partition coefficient, cellulose nanocrystals, dextrans, degree of substitution, polyelectrolyte.

scholarly journals Molecular Weight, Osmotic Second Virial Coefficient, and Extinction Coefficient of Colloidal CdSe Nanocrystals

2002 ◽  
Vol 106 (21) ◽  
pp. 5500-5505 ◽  
Author(s):  
A. Striolo ◽  
J. Ward ◽  
J. M. Prausnitz ◽  
W. J. Parak ◽  
D. Zanchet ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Extinction Coefficient ◽  
Virial Coefficient ◽  
Second Virial Coefficient ◽  
Cdse Nanocrystals

Size, Form and Flexibility of the Rubber Molecule

1962 ◽  
Vol 35 (4) ◽  
pp. 908-917 ◽  
Author(s):  
G. V. Schulz ◽  
A. Mula
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Light Scattering ◽  
Virial Coefficient ◽  
Second Virial Coefficient ◽  
Quantitative Measure ◽  
Degree Of Polymerization ◽  
Bromine Content ◽  
Angle Scattering ◽  
Gaussian Density

Abstract Natural rubber can be brominated in dilute cyclohexane solution, whereby the molecular weight, corresponding to the bromine content, increases. For brominated rubber, increasing bromine content makes cyclohexane an increasingly poorer solvent, which is shown by a contraction of the molecule coils and a decrease in the second virial coefficient. Quantitative results were obtained through viscosity and light scattering measurements. Cyclohexane solutions of brominated rubber containing about 43% bromine have a θ point at room temperature. Here the second virial coefficient is zero and the coil has an ideal Gaussian density distribution. In this state the coil diameter is about 1.6 times bigger than for completely free rotation. A comparison of these data with X-ray low angle scattering could yield a quantitative measure of possible molecular branching. Brominated rubber with about one bromine per isoprene residue is a good starting material for the preparation of electron-microscope samples which can be used for the determination of the molecular weight distribution in rubber. The value of the weight average degree of polymerization determined by an electron microscope is in agreement with that determined through (1) light scattering and (2) ultracentrifuge and diffusion measurements. The molecular inhomogeneity of our sample is of the order of 0.5.

Dependence of the Second Virial Coefficient of Aqueous Solutions of Small Non-Electrolytes on Partial Molar Volume and Molecular Weight of the Solutes

1993 ◽  
Vol 46 (6) ◽  
pp. 929 ◽  
Author(s):  
K Kiyosawa
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Aqueous Solutions ◽  
Molar Volume ◽  
Partial Molar Volume ◽  
Virial Coefficient ◽  
Van Der Waals ◽  
Second Virial Coefficient ◽  
Aqueous Systems ◽  
Quadratic Equations

The osmotic pressures of aqueous solutions of small non-electrolytes, namely ethane-1,2-diol, propane-1,2,3-triol, sucrose and raffinose , were found to be expressible by quadratic equations of the molar concentration, which indicate that these aqueous systems involve no term higher than the second virial coefficient A2. Analysis has shown that A2 mainly does not arise from non-ideality of the aqueous solutions, but its magnitude depends on the partial molar volume of the solute, more precisely on the molecular weight or van der Waals radius or volume of the solute in the aqueous solution.

scholarly journals On the Molecular Weight Dependence of the Second Virial Coefficient of Polystyrene in Toluene

1985 ◽  
Vol 17 (4) ◽  
pp. 657-660 ◽  
Author(s):  
Lina Zhang ◽  
Dajian Qiu ◽  
Renyuan Qian
Keyword(s):  
Molecular Weight ◽  
Virial Coefficient ◽  
Second Virial Coefficient ◽  
Molecular Weight Dependence
Sign in / Sign up

Export Citation Format

Share Document