Azobenzene polymers photoinduced response

The photoinduced flop of the polarization of ferroelectric liquid crystals showing a quick response was achieved by dissolving azobenzene moieties in the liquid crystals.114,11 Photocontrol of the switching behavior of ferroelectric liquid-crystalline polymers (33, Figure 14) was induced by admixing azobenzene derivatives.116... 

The key factor responsible for the photoinduced variations of conformation is the affinity of the azo-polymer for the micelles. Such an affinity, in fact, is likely to be different when the azo side chains are in trans or in cis configuration. When azo-units are in the planar, apolar, trans form, they dissolve within the hydrophobic core of the micelles, forcing the polypeptide chains to assume a coil conformation. Isomerization of the azo units to the skewed, polar, cis form inhibits hydrophobic interactions and causes the azo-units to leave the micelles, thus allowing the polypeptide chains to adopt the a-helix structure (which is favored in the absence of micelles). In other words, the primary photochemical event is the trans cis isomerization of the azobenzene units, but the driving force of the photoresponse should be the different location of the macromolecules relative to the micelles. 

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