TY - JOUR
T1 - Spinodal decomposition of a symmetric critical mixture of deuterated and protonated polymer
AU - Bates, Frank S.
AU - Wiltzius, Pierre
PY - 1989/1/1
Y1 - 1989/1/1
N2 - A nearly symmetric critical mixture (φc = 0.486) of perdeuterated and protonated 1,4-polybutadiene exhibiting an upper critical solution temperature Tc = 61.5 ± 1.5 °C has been quenched from the homogeneous state (≃75 °C) to various temperatures between 25 and 57.5 °C. Light scattering measurements document the subsequent spinodal decomposition process which we describe based on a four-stage model: early, intermediate, transition, and final. The early stage is accounted for by the Cahn theory, yielding initial correlation lengths and effective diffusion coefficients in quantitative agreement with mean-field predictions. Nonlinear effects mark the beginning of the intermediate stage, which exhibits a simple power-law growth of heterogeneity length Lm (t) ∼ tneff, but with a temperature dependent exponent neff. As the composition fluctuation amplitude approaches the equilibrium values, the spinodal decomposition process enters the transition stage, characterized by a decreasing interfacial thickness and an increasing Lm (t). Once the interfacial profile equilibrates, a crossover to the final stage occurs. Subsequent growth of L(t) leaves the morphology unaffected as evidenced by a universal structure factor. These findings are discussed in the context of the current theory and are compared with prior studies involving polymer-polymer and simple liquid mixtures.
AB - A nearly symmetric critical mixture (φc = 0.486) of perdeuterated and protonated 1,4-polybutadiene exhibiting an upper critical solution temperature Tc = 61.5 ± 1.5 °C has been quenched from the homogeneous state (≃75 °C) to various temperatures between 25 and 57.5 °C. Light scattering measurements document the subsequent spinodal decomposition process which we describe based on a four-stage model: early, intermediate, transition, and final. The early stage is accounted for by the Cahn theory, yielding initial correlation lengths and effective diffusion coefficients in quantitative agreement with mean-field predictions. Nonlinear effects mark the beginning of the intermediate stage, which exhibits a simple power-law growth of heterogeneity length Lm (t) ∼ tneff, but with a temperature dependent exponent neff. As the composition fluctuation amplitude approaches the equilibrium values, the spinodal decomposition process enters the transition stage, characterized by a decreasing interfacial thickness and an increasing Lm (t). Once the interfacial profile equilibrates, a crossover to the final stage occurs. Subsequent growth of L(t) leaves the morphology unaffected as evidenced by a universal structure factor. These findings are discussed in the context of the current theory and are compared with prior studies involving polymer-polymer and simple liquid mixtures.
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U2 - 10.1063/1.456901
DO - 10.1063/1.456901
M3 - Article
AN - SCOPUS:36549092257
SN - 0021-9606
VL - 91
SP - 3258
EP - 3274
JO - The Journal of chemical physics
JF - The Journal of chemical physics
IS - 5
ER -