TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The acid anhydride has the structure of formula (2a). The diamine compound is bis(4-aminophenyl) 4,4'-(propane-2,2-diyl)bis(4,1-phenylene)dicarbonate or bis(4-aminophenyl) 4,4'-sulfonylbis(4,1-phenylene)dicarbonate. The polyamic acid has the structure of formula (Ia). The polyimide has the structures of formula (7a) or (8a). The polyimide has a weight average molecular weight of 10000-2000000.Cy1 = trivalent or tetravalent organic group comprising 4-20C cyclic group, 6-20C monocyclic aromatic group, 2-20C condensed polycyclic aromatic group or 2-20C non-condensed polycyclic aromatic group (all optionally substituted), or a group that contains two substituted or unsubstituted 2-20C non-condensed polycyclic aromatic groups that are linked to each other through optionally substituted aromatic group and has the structure of formula -Z1-Ar1-Z2-;Ar1 = optionally substituted aryl;Z1, Z2 = 2-20C non-condensed polycyclic group;A = phenyl group of formula (aa);d = point of attachment to -CO group; andn = 1-500000, where the sum of x and y is 1-500000, and mole ratios of x:y is 0.01:99.99-99.99:0.01.Preferred Process: The carbonate-based diamine compounds are used at 0.5-1.5 moles based on 1 mole of the acid anhydride. The condensing step is performed at 0-200 degrees C. The imidizing is performed at 100-400 degrees C. EXAMPLE - Bis(4-nitrophenyl)4,4'-sulfonylbis(4,1-phenylene)dicarbonate (2.5 g) was dissolved in tetrahydrofuran (50 ml). Palladium on carbon (1 g) was added and hydrogen gas was injected at 1.5-2 atm. The resulting product was agitated for 12 hours. The resulting product was filtered, and vaporized under reduced pressure distillation. The product was recrystallized with methanol to give bis(4-aminophenyl) 4,4'-sulfonylbis(4,1-phenylene)dicarbonate. Bis(4-aminophenyl) 4,4'-sulfonylbis(4,1-phenylene)dicarbonate (1.282 g) was dissolved in N-dimethylacetamide (8.5 ml). Then, another solution was prepared by dissolving bis(6-(2-pyridylamino)pyrid-2-yl)amine (1.35 g) in N,N-dimethylacetamide (8.5 ml). The latter solution was slowly added to the former solution. The mixture was reacted for 18 hours to give polyamic acid.