Three-layer polymer structure

Zhan, Y Van Kirk, E. Xu, P Murdoch, W. J. Radosz, M. Shen, Y. pH-responsive three layer onion-structured nanoparticles for drug delivery. Polym. Mater. Sci. Eng. Prepr. 2006, 94, 139-140. 

Frosch, T. et al. (2010) Nondestructive three-dimensional analysis of layered polymer structures with chemical imaging. Langmuir, 26 (24), 19027-19032. 

Recent work with multi-layer polymer LEDs has achieved impressive results and highlights the importance of multi-layer structures [46]. Single-layer, two-layer and three-layer devices were fabricated using a soluble PPV-based polymer as the luminescent layer. The external quantum efficiencies of the single-layer, two-layer, and three-layer devices were 0.08%, 0.55%, and 1%, respectively, with luminous efficiencies of about 0.5 hn/W, 3 lm/W, and 6 lm/W. These results clearly demonstrate improvement in the recombination current because of the increase in quantum efficiency. The corresponding increase in luminous efficiency demonstrates that the improvement in recombination efficiency was achieved without a significant increase in the operating bias. 

In any case, both models have in common that owing to the positional ordering of the mesogenic side chains, the polymer backbone no longer exhibits a statistical three dimensional coil conformation. Therefore at the phase transformation isotropic to smectic or nematic (cholesteric) to smectic, in addition to the change of the anisotropic packing of the side chains, the main chain has to change its conformation, which must be consistent with the layered smectic structure. A direct interaction... 

We divide this section into three main themes structure, adsorbed amount, and polydispersity. In sec. 5.7a we discuss the structure of the adsorbed layer, paying attention to the volume fraction profile, the composition in terms of loops and tails, the bound fraction, and the layer thickness. Section 5.7b deals with the adsorbed amount as a function of the polymer concentration, the chain length, the solvency and the surface affinity. These two sections are mainly concerned with monodisperse polymer. Polydispersity, where competition between different chain lengths shows up, is treated In sec. 5.7c. 

The reverse-imprinting technique can potentially offer a simple method to fabricate three-dimensional (3D) polymer nanostructures. Such 3D structure can be achieved by simply repeating the process and building up the structure in a layer-by-layer fashion. An example of imprinted three-layer nanostructure, using three different polymers with progressively lower Tg, is shown in Fig. Note that this approach can... 

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