Copolyimides, their microstructure being determined by the method of synthesis, were prepared by copolycondensation of 4,4'-oxydiphthalic anhydride (1 a), 4,4'-carbonyldiphthalic anhydride (1 b), or 1,8 : 4,5-naphthalenetetracarboxylic anhydride with a mixture of two diamines, hexa-, octa-, or dodecamethylene diamine (5 a, 6a, 7a) and cardo-diamines 9,9-bis(4'-aminopheny1)fluorene (3 a) and 3,3-bis(4'-aminophenyl)phthalide (4) or two aromatic diamines, 4,4'-oxydianiline (9) and 2,2-bis(4-aminophenyI)hexafluoropropane (8), at various mole ratios of the comonomers. Blockcopolyimides with five-membered imide cycles were formed by catalytic imidization of the intermediate polymers prepared by addition of the solid dianhydride to a solution of the mixture of the two diamines, whereas the thermal cyclization of such polymers and the one-step high-temperature synthesis led to random copolyimides. The thermal and mechanical properties of the copolyimides with various microstructure and their solubility in organic solvents were compared. *) Cardo groups (cardo = loop) are those incorporated into the main polymer chain with one atom which is a part of a cyclic system. Such groups are derived from phthalide, phthalimidine, fluorene, anthrone etc. They endow a polymer with very specific properties, like enhanced thermostability, excellent solubility etc. Makromol. Chem. 184, No. 2, February 1983 0025-1 16)83/$03.00 l a : R = O b: R = C O 2 gjg RHN ' ' NHR 3 a : R = H b : R = SYCH,), 4 8 9
Experimental PartThe initial monomers used and the methods of their purification are presented in Tab. 1.
N,N'-bis(trimethylsily1)hexamethylenediamine (5 b) and N, N'-bis(trimethylsi1yI)octamethyle-nediamine (6b) were synthesized according to the known method5).
N,N'-Bis(trimethylsilyl/dodecamethylenediamine (7 b):In a one-necked 100 ml flask were placed 20 g of dodecamethylenediamine (7 a) and then 50 ml of diethylaminotrimethylsilane '). The reaction mixture was stirred and heated for 3 h at 120°C (on a silicone bath) in argon atmosphere evaporating diethylamine, which was condensed in a trap cooled with solid CO,/acetone. After diethylamine evolution has ceased the reaction mixture was cooled and excess diethylaminotrimethylsilane was distilled off at 80°C in the vacuum of a water pump.The reaction mixture was then evacuated (residual pressure of 1 -4 mbar) at 90 -100 "C for 4 h and the resulting product was distilled at 150-151 "C/O,Ol mbar. Yield: 68%.C18H,N2Si2 (344,7) Calc. Si 15,96, 16,05 9,9-Bis(4'-trimethylsilyIaminophenyl)fluorene (3 b): In a one-necked 100 ml flask were placed 3,48 g of 9,9-bis-(4-aminophenyl)fluorene (3a), then 50 ml of chlorobenzene. The mixture was