SYNTHESIS AND PROPERTIES OF POLYARAMIDES MODIFIED WITH FLUORINE STRUCTURE
Firstly,a novel diamine monomer 9,9-bis(3,5-dimethoxy-4-(4-amino-2-methylphenoxy)phenyl)containing fluorene was prepared by three-step organic reaction.This monomer was then used to synthesize a series of polyarylamides(PA 3a-3d)with fluorine by low-temperature solution condensation with four commercial aromatic diacids(terephthalic acid,2,2-bis(4-carboxyphenyl)hexafluoropropane,4,4-diphenyl ether dicarboxylic acid,and 4-tert-butylisophthalic acid).The structure and properties of these polymers were characterized by 1H NMR,FT-IR and GPC.The solubility,thermal properties,optical properties and mechanical properties of the polymers were investigated.The results showed that the polyarylamides could be dissolved in high-boiling polar solvents such as DMAc,NMP,DMF,and pyridine and low-boiling point solvent THF.The glass-transition temperature Tg of these polymers ranged from 217 ℃ to 234 ℃.The 10％mass loss temperature in air and nitrogen were both above 450 ℃,indicating excellent thermal stability.The prepared films exhibited excellent mechanical properties,with tensile strength more than 76.6 MPa and elongation at break above 8.7％.These polymers with fluorene structures showed excellent comprehensive properties.
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