A new type π-conjugated copolymer was obtained by the polymerization of 2

5-dibromothiophene Grignard reagents and 4

4′-diiodoazobenzene through nickel（II） complexes catalyzed cross-coupling reactions.Both monomers and polymer were characterized by（）

1

H-NMR

FT-IR

UV-Vis and fluorescent spectroscopy

XRD and thermal analysis.The results from FT-IR and（）

1

H-NMR showed that the copolymer had the structure as expected.The copolymer obtained by this method gives isolated yields of 80%.Intrinsic viscosity [η] of the polymer is about 0.53 dL/g in sulfuric acid at 25℃.The polymers are brown powders and have good solubility in common organic solvents such as dimethyl sulfoxide（DMSO）

dimethylformamide（DMF）

N-methyl-2-pyrrolidone（NMP）

CHCl

3

and slightly soluble in tetrahydrofuran（THF）

benzene

toluene etc.The UV-Vis spectra of the copolymer in CHCl

3

showed one broad absorption peak at 384 nm

and the PL spectrum gave a peak at 523 nm.This indicates that the polymers have good fluorescence.It was observed that the copolymer was quite sensitive to acids

and the acidichromatic behavior was investigated applying organic acids such as CF

3

COOH and CH

3

SO

3

H.After adding acids

CF

3

COOH and CH

3

SO

3

H

the color of the polymers chloroform solution changed from yellow to deep green or violet.Addition of triethylamine（Et

3

N） in an equal amount to the acid leads to almost complete return of the original color immediately.XRD spectrum of the polymers revealed that the polymer had no obvious crystalline structure

however

showed somewhat orderly packed structure.The TGA results indicated that the polymer began to decompose above 326℃

having good heat stability.It is expected to be used as polymer materials with electro-optical properties.