Synthesis and characterization of copolymers with 2,5-bis [(5-decaoxyphenyl)-1,3,4-oxadiazole]styrene monomer and vinyl carbazoles

By radical polymerization initiated with BPO, a novel series of random copolymers of 2,5-bis[(5-decaoxyphenyl)-1,3,4-oxadiazole]styrene (POC10) monomer and vinyl carbazoles (NVKs) are synthesized for first time. The elemental analyses of the copolymers indicated that POC10 and NVK contents in the copolymers were very close to the feed compositions. Molecular weight and its distribution of the copolymers were experimentally elucidated using a gel permeation chromatography. They all have good solubility in common organic solvents, such as chloroform, toluene, and tetrahydrofuran and so on. The structures of the copolymers were characterized by IR and ¹H-HNMR. Their weight loss was less than 5% on heating to about 270°C under nitrogen atmosphere. The DSC graph has only one glass transition, which represents there is no phase-separation in copolymer. The photoluminescence properties were characterized by UV absorption and fluorescence spectrum in detail. The random copolymers exhibited a PC10-segment dominated UV absorption peak at 320 nm and narrow band gap NVK absorption at 228 nrn. Under UV excitation, these copolymers emitted bright blue fluorescence at abound 414-447 nm in THF solution and 435-446 nm in thin films form. Their photoluminescences are both in blue light area. Compared with the solution PL, complete PL excitation energy transfer from the NVK segment to the POC10 unil could be achieved by film PL at lower NVK content. With units of carbazole increasing, fluorescence quantum yield of copolymers decreases.