(98ah) Capillary Instabilities of An Array of Parallel Polymer Stripes Confined in Another Immiscible Viscous Matrix

We study the simultaneous morphological evolution of parallel polymer stripes (PS in particular), which were non-axisymmetrically embedded in another immiscible polymer layer (PMMA), which was confined on a rigid substrate. Capillary instabilities of the confined PS stripes were observed when annealed at a temperature above the glass transition temperatures of both polymers. The influences of the stripe-to-matrix viscosity ratios and volume ratios on the morphological development were systematically examined. Both were found to modulate the instabilities and result in distinctive morphologies. When the matrix layer was thin, we observed the influences of the substrate confinement on the phase-correlation in the breakup of neighboring stripes, engendered by the non-deformable nature of the substrate. With the increase of substrate confinement, the simultaneous breakup of the parallel polymer stripes transitioned from non-correlation to in-phase, irrespective of the viscosity ratio between PS and PMMA.