Synthesis and characterization of novel fluorinated azopolyamides

Novel soluble fluorinated azopolyamides 4a-d were synthesized by reacting 2-trifluoromethyl-4,4’-diaminodiphenyl ether 2 with various azodibenzoyl chlorides 3a-d using the low temperature solution polycondensation technique. The fluorinated diamine 2 was prepared through the nucleophilic substitution reaction of 4-nitrophenol and 2-chloro-5-nitrobenzotrifluoride via catalytic reduction catalytic reduction with hydrazine and Pd/C. All of the fluorinated azopolyamides exhibited excellent solubility at room temperature in strong polar solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and N-methyl-pyrrolidinone (NMP). Inherent viscosities of the azopolyamides were found to range from 0.85 to 1.35 dl/g, and those azopolyamides could be cast into flexible and tough films from DMAc solutions. The azopolyamides showed that the glass transition temperatures (Tg) were between 231 and 259oC, and the char yields of all the azopolyamides except for 4d at 800oC in nitrogen atmosphere were above 47%. Furthermore, all the azopolyamides exhibited thermal and photochromic properties.