Correlation radii for polystyrene (PS) in poor and ⊖ solvents from dynamic light and small angle neutron scattering. new data for ps/acetone. remarks on ps/acetone, ps/cyclohexane, and ps/methylcyclohexane

W. Van Alexander Hook, Hannah Wilczura, Attila Imre, Luis P. N. Rebelo, Yuri B. Melnichenko

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Abstract

Dynamic light scattering (DLS) and small-angle neutron scattering (SANS) correlation radii, £ and |SANS, are reported for polystyrene (PS)/acetone-A6 (ACh) (DLS) and PS/ACd (DLS and SANS) solutions at near-critical concentration for (7.5 × 103 ≤ Mw/amu ≤ 25 × 103), (0 ≤ P/MPa < 120) and (12 ≤ t/°C < 91), during pressure and temperature quenches ending at or near precipitation. The data are well described in the (T,P)yer projection using the multidimensional reduced scaling formalism introduced previously. The analysis yields scaling exponents (v ∼ VSANS = 0.65 ± 0.06) which are in agreement with the theoretical value, VTH = 0.63, but (f)° and £SANS are offset from each other, ((£)/|SANS) ∼ 3. The superscript "o" refers to correlation radii calculated from monomodal DLS correlograms using the StokesEinstein relation, (£)° = kBT/(6πηoD). D is the DLS diffusion coefïïcient, and ηo is the pure solvent viscosity. For PS/cyclohexane (CH) and PS/methylcyclohexane (MCH) solutions, (£°/esANs) ∼7 and ∼20, but for all three solvents, agreement improves when ηo is replaced with η, the solution viscosity. Then, (£/£SANS) ∼0.3, ∼0.2, and ∼3 for PS/AC, PS/CH, and PS/MCH, respectively. The results indicate the two probes are responding to the same or closely related clustering phenomena.

Original languageEnglish
Pages (from-to)7312-7318
Number of pages7
JournalMacromolecules
Volume32
Issue number21
DOIs
Publication statusPublished - 19 Oct 1999

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