Incorporation of lead phthalocyanine into periodic nanolayered assemblies for advanced optical systems



Periodically structured polymeric materials can lead to the next generation of electro-optic and nonlinear optical devices for applications in information technology. Layer-multiplying melt coextrusion is an attractive method for fabricating periodic structures with thousands of alternating polymer microlayers or nanolayers. Many advanced applications for periodic polymeric structures would be enabled by locating a photoactive dye in one or both layers. However, it is anticipated that due to the thinness of the individual layers and the relatively low molecular weight of many dyes, a substantial fraction of the dye will diffuse from the doped layers into the undoped layers during melt coextrusion. In the present study, we demonstrate two methods for confining the activity of a photoactive dye, lead phthalocyanine, to the doped layers. Polycarbonate containing lead phthalocyanine was coextruded with undoped polyester as an assembly of 128 alternating 86 nm-thick layers. Using the absorption spectra, we demonstrated that a high concentration of the monomer form persisted in the polycarbonate layers, whereas the lead form was converted to the less active lead-free form in the polyester layers. Thus, the active monomer form of PbPc(β-CP)4 was maintained selectively in the polycarbonate layers. In the second approach, the coextrusion process was altered so that the alternating polycarbonate and polyester layers were separated by a thin layer of a barrier polymer. The barrier layer prevented diffusion of the dye during melt coextrusion and the dye remained selectively in the polycarbonate layers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009