Abstract
A semi-alicyclic dianhydride monomer, 4,4'-dihydroxybiphenyldicyclohexanecarboxylate- 3,3',4,4'-tetracarboxylic acid dianhydride (HTA-BP) was prepared according to a modified procedure reported in the literature with trimellitic anhydride as the starting material. A series of semi-alicyclic polyimide (PI) resins were synthesized from HTA-BP and aromatic diamines, including 4,4'-bis[(4-aminophenoxy-2-trifluoromethyl)] biphenyl (6FBAB) for PI-1, 2,2'-bis[(4-aminophenoxy)phenyl]hexafluoropropane (BDAF) for PI-2, 4,4'-diamino- benzanilide (DABA) for PI-3, and 2-chloro-4,4'-diaminobenzanilide (Cl-DABA) for PI-4 via a two-step chemical imidization procedure. The derived PI resins are easily soluble in polar aprotic solvents, such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), and γ-butyrolactone (GBL). High-whiteness PI ultrafine fabrics with the yellow indices lower than 4.0 were successfully prepared by the electrospinning procedures from the PI solutions in DMAc. The PI fabrics exhibited good thermal stability with the 5% weight loss temperatures over 400 oC and glass transition temperatures higher than 190 oC.
