ESR and optical study of photo-orientation in azobenzene-containing liquid-crystalline polymer

J Phys Chem B. 2013 Oct 10;117(40):12328-38. doi: 10.1021/jp4080493. Epub 2013 Sep 25.

Abstract

We report a comprehensive experimental study of photoinduced processes in azobenzene-containing liquid-crystalline polymer. The kinetic and optical characteristics of the photoisomerization reaction and photo-orientation process have been determined. The spin probe technique has been used to elucidate the details of orientation order and rotational mobility of molecular fragments within the liquid-crystalline polymer. The evolution of orientation order parameters <P2>, <P4>, and <P6> in the course of photoinduced ordering of the material as well as the change of liquid-crystalline domain sizes have been studied quantitatively. The obtained experimental results are compared with the predictions of the existing models of photo-orientation.