Molecular weight determination of macromolecules with a new simplified and coherent light scattering method

Comparison of Proutière and Carr−Zimm Theories for Static Light-Scattering Molecular Weight Determination: Application to Surfactants in Solution

“…This work completes the validation process that has started with the study of macromolecular solutions. − In the range 0.33−4.67 kg/mol, the new equations lead to molecular weight values that are in good agreement with the M n ones, which confirms the validity of Proutière's theory in the case of low polymer weight solutions.…”

“…Usually, for polymer or macromolecular solutions, the ∂ n /∂ρ 2 increment is often very difficult to obtain with accuracy (because very dilute solutions give very low refractive index variations) and is, in many cases, deduced from rough approximations. − In this article, the variation of n vs ρ 2 is linear enough to get the ∂ n /∂ρ 2 increment from the slope of the regression for each compound. Experimental values of the slopes needed in the two methods, that is, ∂ n /∂ρ 2 for the Carr−Zimm formula (eq 6), ∂ f r /∂ w = ∂( f r − 1)/∂ w and ∂( F r )/∂ w = ∂( F r − 1)/∂ w for the Proutière method, are reported in Table .…”

“… Experimental data needed ( I r , ρ, w ) for the application of the Carr−Zimm formula (eq 6) and of Proutière's method (eq 23) are reported in Table . Values of the depolarization ratio have been estimated from the relation which neglects the contribution of the solute anisotropy of polarizability to the horizontally scattered light (with ρ n 1 = 0.263, the depolarization ratio of the pure liquid CH 2 Cl 2 ) . A similar approximation is used in the CZ method in which I H is also not determined (see for example eq 4).…”

“…• to true values for molecular weight determination from Rayleigh light scattering and refraction in liquids. − …”

Molar Mass, Radius of Gyration and Second Virial Coefficient from new Static Light Scattering Equations for Dilute Solutions: Application to 21 (Macro)molecules

“…We used R ref = (14, 33, 40) 10 À4 m À1 at l = 632.8, 514.5 and 488 nm respectively. The following values of I 1 /I ref were taken : 0.174 25 (methanol), [16] 0.298 (cyclohexane), [16] 0.41 (dichloromethane) [18] and 1 for toluene. For the 1,2-dichloroethane solvent, the I 1 /I ref ratio has not been found; therefore, M 2 and A 2 have not been determined by the CZ method for dibenzyl.…”