Molecular weight dependence of the second virial coefficient for linear flexible polymers in good solvents

1985 ◽  
Vol 18 (8) ◽  
pp. 1637-1638 ◽  
Author(s):  
Hiroshi Fujita ◽  
Takashi Norisuye

1985 ◽  
Vol 17 (4) ◽  
pp. 657-660 ◽  
Author(s):  
Lina Zhang ◽  
Dajian Qiu ◽  
Renyuan Qian




2008 ◽  
Vol 86 (6) ◽  
pp. 503-511 ◽  
Author(s):  
Stephanie Beck-Candanedo ◽  
David Viet ◽  
Derek G Gray

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.



2002 ◽  
Vol 106 (21) ◽  
pp. 5500-5505 ◽  
Author(s):  
A. Striolo ◽  
J. Ward ◽  
J. M. Prausnitz ◽  
W. J. Parak ◽  
D. Zanchet ◽  
...  


1962 ◽  
Vol 35 (4) ◽  
pp. 908-917 ◽  
Author(s):  
G. V. Schulz ◽  
A. Mula

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.



1993 ◽  
Vol 46 (6) ◽  
pp. 929 ◽  
Author(s):  
K Kiyosawa

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.



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