Study On Preparation And Properties Of Main-Chain Azo Polyamides

Polymers with azobenzene linkages are increasingly viewed as promising candidates in high molecular material research front domain. Having both optical activity of azobenzene and outstanding mechanics performance of high polymer material, it has potential applications for optical data storage, nonlinear optical materials, liquid crystal polymer, photoelectric devices, photoregulation of bioactivity of biomolecule and nanometer technology.In the first part of the paper, the synthesis of azobenzene-4,4'-dicarbonylchloride is optimized. And a series of aromatic azobenzene modified polyamides were prepared from four kinds of aromatic diamides and azobenzene-4,4'-dicarbonylchloride by low temperature solution polycondensation. With a series of well designed experiments, all the factors which may affect the polycondensation are tested, and the optimized factors are found. The factors researched in the article including monomer concentration, acid receptor, salt concentration , reaction temperature, reaction time and so on.FT-IR, ~1H NMR and Elemental Analysis were applied to characterize these materials. The new azo polyamides(Azo-PA) thus obtained were tested of their capability to form lyotropic solutions by polarizing light microscope(PLM). The influence of the twisted and non-coplanar phthalazinone structure on the close packing of the Azo-PA main chains was tested by WAXD. And their other properties such as inherent viscosity, solubility, thermal properties, crystallinity of these aromatic polyamides were also measured. The Azo-PA has poor solubility. It is soluble only in highly concentrated sulfuric acid and insoluble in common organic solvents. The polyamides had relatively high inherent viscosities, ranging from 2.23 to 4.26 dL/g. These polyamides showed Tg values between 202 and 228℃. And they had good thermal stability, associated with 5% and 10% weight loss temperatures in the range of 412-440℃and 445-465℃in nitrogen, respectively. WARD measures indicated these polyamides were semicrystalline in nature.The Azo-PA presents a combination of outstanding properties such as high thermal stability, good chemical resistance, lyotropic liquid crystalline property and excellent mechanical properties. In application, lyotropic liquid crystalline property of Azo-PA or similar polyamides has received considerable commercial and scientific interest. Unfortunately, few aromatic polyamides can exhibit lyotropic liquid crystalline properties in common organic solvents, due to their limited organic solubility. The too high rigidity and too strong intermolecular hydrogen bonding in these polyamides result in their poor solubility in most organic solvents, restricting their applications. In this thesis, our efforts have been focused on modificating chemical structures of rigid aromatic of polyamides. By introducing carbanion, we prepare polyelectrolyte while maintaining the desired properties.