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Transient Target Patterns in Phase Separating Filled Polymer Blends



Alamgir Karim, Jack F. Douglas, G Nisato, D W. Liu, Eric J. Amis


Recent simulations have indicated that the presence of filler particles in a phase separating blend can induce the development of composition waves having the symmetry of the filler particles. We investigate these predictions through atomic force microscopy (AFM) measurements on ultrathin (L approximately equal to} 100 nm) polystyrene and poly (vinyl methyl) ether blend films containing a small concentration of model filler particles (silica particles having a diameter approximately equal to} 100 nm). The filled blend films were spun cast on acid cleaned silica wafers and phase separation was induced by a temperature jump into the two-phase region (T = 145 C) of the bulk polymer blend. AFM measurements on solvent washed filled films show that the silica particles strongly associate with the substrate so that the filler particles represent a quenched disorder perturbation of the film phase separation. The presence of the filler particles leads to the development of circular composition waves (target patterns) about the filler particles during the intermediate stage of phase separation. These target patterns break up as the background spinodal phase separation pattern becomes comparable to the scale of composition enrichment at the center (bull's eye) of the target pattern. Our observations are consistent with idealized two-dimensional Cahn-Hillard-Cook simulations on the phase separation of polymer blends having a small concentration of filler particles.
No. 18


circular waves, fillers, phase separation, spherical waves, target patterns, thin film blends


Karim, A. , Douglas, J. , Nisato, G. , Liu, D. and Amis, E. (1999), Transient Target Patterns in Phase Separating Filled Polymer Blends, Macromolecules, [online], (Accessed June 24, 2024)


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Created August 31, 1999, Updated October 12, 2021