The synthesis of segmented polyethers (PO) contg. oxadiazole units was carried out in a two-step scheme involving condensation reaction of acid chlorides with diphenoxyalkane dihydrazides; the polyazides were subsequently subjected to cyclization to form the oxadiazole moieties, in the presence of POCl3. Because of the anisotropic shape of oxadiazole-conjugated segments, the copolymers of the series show the monotropic nematic phase to be somewhat different from that obsd. in the case of the low mol. wt. analogous compds. In that case, high ordered liq. cryst. smectic phases are reported while the nematic phase is obsd. just in few cases. According to previous reports on oxadiazole-contg. materials, the POs show high photoluminescence activity in the blue region of the visible spectra. The good soly. in chlorinate solvents allows prepn. of films with homogeneous thickness by spin coating. The glass transition temp. is 100-120a, which ensures good stability of film morphol. at room temp. For these features, the POs are potential candidate materials for fabrication of blue-light-emitting devices.
Synthesis and Characterization of a New Class of Nematic Photoluminescent Oxadiazole-Containing Polyethers
Amendola E;
2003
Abstract
The synthesis of segmented polyethers (PO) contg. oxadiazole units was carried out in a two-step scheme involving condensation reaction of acid chlorides with diphenoxyalkane dihydrazides; the polyazides were subsequently subjected to cyclization to form the oxadiazole moieties, in the presence of POCl3. Because of the anisotropic shape of oxadiazole-conjugated segments, the copolymers of the series show the monotropic nematic phase to be somewhat different from that obsd. in the case of the low mol. wt. analogous compds. In that case, high ordered liq. cryst. smectic phases are reported while the nematic phase is obsd. just in few cases. According to previous reports on oxadiazole-contg. materials, the POs show high photoluminescence activity in the blue region of the visible spectra. The good soly. in chlorinate solvents allows prepn. of films with homogeneous thickness by spin coating. The glass transition temp. is 100-120a, which ensures good stability of film morphol. at room temp. For these features, the POs are potential candidate materials for fabrication of blue-light-emitting devices.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
