Molecular weights of polystyrenes in toluene solutions by light scattering. Comparison between classical values and values deduced from a new method

Proutière's theory of molecular weight (M) determination by Rayleigh scattering has been tested on surfactants in solution, and it has been compared to the classical Carr-Zimm (CZ) method. Both methods make use of time-averaged scattering intensity, refractive index, and density measurements. Monoethers of poly(ethylene glycol) samples have been studied in the range 0.33-4.67 kg/mol of M. Under those conditions, it has been shown that Proutière's method leads to a far better agreement with formula weight (M) values than the CZ method because Proutière theory takes into account the specific mean polarizability of the solvent and derivative of the solution density with respect to the solute mass concentration, which is counter to CZ theory.

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

Section: Introductionmentioning

confidence: 99%

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

Evain¹,

Illien²,

Chabanel³

et al. 2007

J. Phys. Chem. B

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“…[17] Accordingly, it is hardly surprising that the CZ method gives the lowest MAD and MD relative to supplier values (7.4 %, + 0.4 %), as opposed to a(gas) (9.3 %, + 3.0 %) and a(liq) (15 %, + 15 %) values. The M 2 [a(gas)] values are closer to M 2 (CZ) than the M 2 [a(liq)] values, and both are always higher than the CZ values.…”

Section: Molar Massmentioning

confidence: 98%

“…On the contrary, a(gas) and a(liq) equations lead to M 2 in better agreement with expected values (MADs less than 9 %) with no @1/@1 2 sign relation. This brings to the foreground the physical significance of Equations (18) and (19) with respect to Equation (17). In terms of MAD, a(gas) and a(liq) results only differ by 3 % on average; this emphasize the soundness of Equation (21).…”

mentioning

confidence: 88%

“…For example, the uncertainty in the absolute Rayleigh ratio of toluene at 633 nm and 25 8C is greater than 10 %. [17] A more serious point is that the absolute R values are sometimes not really independent values. Indeed, in many cases they are only assumed values deduced through the CZ equation for known M 2 values.…”

mentioning

confidence: 99%

“…Equation (17) neglects the specific polarizability of the solvent " a 1 =M 1 and a term proportional to the derivative of the solution density 1 [14]; n at w = 0.0542 is calculated from the linear regression n = f(1 2 ) obtained by using n from Table 2 in ref. [14].…”

mentioning

confidence: 99%

See 2 more Smart Citations

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

Illien

Ying

2009

ChemPhysChem

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New static light scattering (SLS) equations for dilute binary solutions are derived. Contrarily to the usual SLS equations [Carr-Zimm (CZ)], the new equations have no need for the experimental absolute Rayleigh ratio of a reference liquid and solely rely on the ratio of scattered intensities of solutions and solvent. The new equations, which are based on polarizability equations, take into account the usual refractive index increment partial differential n/partial differential rho(2) complemented by the solvent specific polarizability and a term proportional to the slope of the solution density rho versus the solute mass concentration rho(2) (density increment). Then all the equations are applied to 21 (macro)molecules with a wide range of molar mass (0.2500 kg mol(-1)), for which the scattered intensity is no longer independent of the scattering angle, the new equations give the same value of the radius of gyration as the CZ equation and consistent values of the second virial coefficient.

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Molecular weights by light scattering in macromolecules solutions. Large deviations observed between a new method and the classical method

Beignon

Bamba

Evaina

et al. 1999

Journal of Molecular Structure

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Molecular weights of polystyrenes in toluene solutions by light scattering. Comparison between classical values and values deduced from a new method

Cited by 3 publications

References 12 publications

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

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

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

Molecular weights by light scattering in macromolecules solutions. Large deviations observed between a new method and the classical method

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