NEW POLYMER SYNTHESES .68. KEVLAR-TYPE POLYARAMIDES DERIVED FROM 2-PHENOXY-1,4-DIAMINOBENZENE

2-Phenoxy-1,4-diaminobenzene was prepared from phenoxyterephthaloyl chloride and trimethylsilyl azide. Its N,N'-bis(trimethylsilyl) derivative was polycondensed with terephthaloyl chloride and various substituted terephthaloyl chlorides. On the basis of WAXS and DSC measurements, all polyaramides are semicrystalline. Their thermostability in air is relatively low despite a fully aromatic character. When the side chain of the terephthaloyl units has a length of three aromatic rings, the melting points are reduced below 350-degrees-C and reversible melting and crystallizing becomes possible. Surprisingly none of the meltable polyaramides formed an anisotropic melt. However, the polyaramides bearing one or two phenoxy groups formed a lyotropic solution in concentrated H2SO4. The solubilities of all polyaramides were determined in eight different solvents. Some polyaramides are soluble in aprotic organic solvents such as dimethyl sulfoxide or N-methyl-2-pyrrolidone.