Abstract
Using computer simulations, we establish an approach for creating defect-free, periodically ordered polymeric materials. The system involves ternary mixtures where the and components undergo a reversible photochemical reaction. In addition, all three components are mutually immiscible and undergo phase separation. Through the simulations, we model the effects of illuminating a three-dimensional (3D) sample with spatially and temporally dependent light irradiation. Experimentally, this situation can be achieved by utilizing both a uniform background light and a spatially localized, higher intensity light, and then rastering a higher-intensity light over the 3D sample. We first focus on the case where the higher-intensity light is held stationary and focused in a distinct region within the system. The component is seen to displace the and within this region and replicate the pattern formed by the higher-intensity light. In effect, one can write a pattern of onto the binary system by focusing the higher-intensity light in the desired arrangement. We isolate the conditions that are necessary for producing clearly written patterns of (i.e., for obtaining sharp interfaces between the and domains). We next consider the effect of rastering a higher-intensity light over this sample and find that this light “combs out” defects in the blend as it moves through the system. The resulting material displays a defect-free structure that encompasses both a periodic ordering of the and domains and a well-defined motif of . In this manner, one can create hierarchically patterned materials that exhibit periodicity over two distinct length scales. The approach is fully reversible, noninvasive, and points to a novel means of patterning with homopolymers, which normally do not self-assemble into periodic structures.
5 More- Received 31 January 2006
DOI:https://doi.org/10.1103/PhysRevE.74.011502
©2006 American Physical Society