Controlling Morphology of Polymer Blends by Using Spatial and Temporal Modulation

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The main purpose of this research project is to manipulate and control the morphology (characteristic, length scales and its distribution) of polystyrene/poly (vinyl methyl ether) (PS/PVME) blends using spatial and temporal modulation. For this purpose, ultraviolet light was used as an external modulating source and the polystyrene component of the blends were made photosensitive by labeling with photo-reactive groups such as anthracene (A) and stilbene (S). The following experiments were performed : (1) Phase separation induced by spatially periodic forcing ; (2) Phase separation induced by temporally periodic forcing ; (3) Phase separation induced by reversible cross-linking reaction ; (4) Phase separation manipulated by competing interactions.In summary, morphology of a polymer can be well controlled by the characteristic length scales as well as the characteristic time scales of the external modulation. The elastic stress generated by the chemical reactions couples to critical concentration fluctuations, broadening the length scale distribution of the morphology. The competition between stress-induced broadening and reaction-induced sharpening plays the key role in the resulting morphology.