Liquid crystalline coumarin polymers, 1 Synthesis and properties of side-group liquid crystalline polymers with coumarin moieties

This paper deals with two series of novel side-group liquid crystalline pol ymers containing coumarin(2H-1-benzopyran-2-one) moieties. Several kinds of polymethacrylates of Series I (Fig. 1) containing a 7- unit in the side gr oup with or without substituent at 3 or 4 position of coumarin ring were pr epared, in order to study the influence of spacers, tail groups and the pos itions of the tail groups on their liquid crystalline properties. These pol ymethacrylates (Series II, Fig. 1) containing a phenyl 7-octyloxycoumarin-3 -carboxylate, which consisted of a turned ester group between the aromatic rings in the central unit of side group as compared to Series I, were also prepared. The of the thermal behavior of the two series that the structure of the side-group significantly crystalline properties of the polymers. tha t the polymers in Series I with substituents position of the coumarin ring exhibited mesophase with a wide temperature range, whereas the polymers wit h substituents at the 4 position showed no mesophase. In each polymer of Se ries I tended to exhibit a state, whereas each polymer of Series II tended to exhibit a crystalline state. This would be due to the different of side groups of the polymers in Series I and II, It was also revealed thar the UV -Vis absorption and fluorescence spectra were influenced by their mesogenic structures and chromophore aggregations. Furthermore, the preliminary resu lts about the emission spectra suggested that the annealing of the polymer film had a great; influence on its fluorescence property.