SYNTHESIS AND CHARACTERIZATION OF NEW SOLUBLE POLYIMIDES FROM 3,3',4,4'-BENZHYDROL TETRACARBOXYLIC DIANHYDRIDE AND VARIOUS DIAMINES

New soluble polyimides were prepared from a series of diamines and a t etracarboxylic dianhydride with a benzhydrol unit, 3,3',4,4'-benzhydro l tetracarboxylic dianhydride (BHTDA), by one-step method polymerizati on. The diamines containing flexible units, bulky substituents, and/or noncoplanar conformation unit were prepared by the reaction of the co rresponding bisphenol precursors and p-chloronitrobenzene, followed by catalytic reduction of the dinitro compounds. The polyimides obtained were soluble in various solvents such as N-methyl-2-pyrrolidone, N,N- dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, pyridine , gamma-butyrolactone, m-cresol, and even tetrahydrofuran except for p olymer PId. The polymers were amorphous and had number-average molecul ar weight (M-n) in the range (3.0-10.2) x 10(4). The glass transition temperatures (T-g) of the polymers ranged from 268 to 341 degrees C. T hese polymers exhibited good thermal stability without significant wei ght loss up to 420 degrees C. The temperatures at 10% weight loss rang e from 457 to 524 degrees C in nitrogen and 449 to 519 degrees C in ai r, respectively. The polyimide films were found to be transparent, fle xible, and tough. The films had a tensile strength range 72-105 MPa, a n elongation range at break of 4-7%, and a Young's modulus range of 2. 18-2.85 GPa.