Crystallization of Binary Polymer Blends

Polymer blends are known to be one of the exciting materials to prepare nanoscale devices via self-assembly. We report dynamic Monte Carlo simulation results on the crystallization of A/B binary polymer blends with varying composition, wherein both the components are crystallizable. We model A-polymer as high melting component and hence its crystallization precedes the crystallization of B-polymer upon cooling from a homogeneous melt. The morphological development is controlled by the interplay between crystallization driving force (attractive) and de-mixing energy (repulsive) between the components. With increasing the composition of B-polymer, macrophase separation, crystallization and lamellar thickness follow a non-monotonic trend. This non-monotonic trend is attributed to the composition-heterogeneity in the blend. When one component is relatively less compared to the other, its mobility is reduced affecting crystalllization temperature. As a result, transition happens at a relatively lower temperature (viz., enhanced thermal driving force). Isothermal crystallization reveals that the crystallization behavior and crystal morphology strongly depends on the mode of cooling. Two-step, compared to on-step isothermal crystallization provides better crystalline structures.