Preparation of Poly(alkylenebenzimidazole) by Ruthenium Complex Catalyzed Polycondensation of 3,3'-Diaminobenzidine with #alpha#, #bomega#-Diols

摘要

The reactions of 3,3'-diaminobenzidien with 1,12-dodecanediol in 1 : 1 -1: 3 molar ratios in the presence of RuCl_2 (PPh_3)_3 catalyst give poly(alkylenebenzimidazole), [-(CH_2)_11-O-(CH_2)_11-iM-/-(CH_2)_10-Im-]_n (IM: 5,5'-dibenzimidazole-2,2'-diyl) (I_a-I_d) in 71-92% yields. The relative ratio between the [(CH_2)-11-O-(CH_2)_11-Im-]unit (A) and the [-(CH_2)_10-Im-] unit (B) in the polymer chain varies depending on the ratio of the substrates used. The polymer I_a obtained from teh 1 : 3 reaction contains these structural units in a 98 : 2 ratio. The polymers are soluble in polar solvents such as DMF (N,N-dimethylformamide), DMSO (diemthyl sulfoxide), and NMP (N-methyl-2-pyrrolidone) and have molecular weights M_n (M_w) of 4,200-4,800 (4,800-6,500) by GPC (polystyrene standard). The polymerization of the diol and 3,3'-diaminobenzidine in higher molar ratios leads to partial cross-linking of the resulting polymers I_e and I_f via condensation of imidazole NH group with CH_2OH group. Similar reactions of 3,3'-diaminobenzidine with #alpha#, #omega#-diols, HO(CH_2)_m OH (m = 4-10), in a 1 : 3 molar ratio give the polymers containing [-(CH_2)_(m-1)-O-(CH_2)_(m-1)-Im-] [-(CH_2)_(m-2)-Im-] units with partial cross-linked structures.