TECHNOLOGY FOCUS - POLYMERS - Preferred Property: The crystallinity level in the copolymer is at least 0.5%.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Structures: The first or third unit is of formula (IV), (V), (IVasterisk), or (Vasterisk), and is functionalized, preferably sulfonated to provide ion-exchange sites. The phenyl groups in these formulas are optionally substituted. The second unit has the formula (IV) or (IVasterisk).m, r, s, t, v, w, z = 0 or positive integer;E, E' = O, S, or direct link;G = O, S, direct link, or -O-phenyl-O-;Ar = moiety of formula (i)asterisk, or (i)-(x).Preferred Units: The first or third unit is a repeat unit including aromatic group containing moieties linked by -SO2-, -CO-, and/or -Q-, where Q is O or S. The second unit is a repeat unit including aromatic group containing moieties linked by -CO- and/or -Q-. The third unit is non-crystallizable with polyarylether ketones, polyarylthioether ketones, or with the second unit. The third unit comprises a fourth unit of formula -Q-Z-Q-. The fourth unit is not symmetrical about an imaginary line passing through the -Q- moieties. The fourth unit is not derived from dihydroxybenzophenone substituted by groups Q at the 4- and 4'- positions. Preferably, the first unit is -ether-phenyl-ketone-phenyl, ether-phenyl-ketone-phenyl-ether-phenyl-ketone-phenyl-ketone-phenyl, -ether-biphenyl-ether-phenyl-ketone-phenyl, -ether-phenyl-ether-phenyl-ketone-phenyl, -ether-naphthalene-ether-phenyl-ketone-phenyl-, -ether-phenyl-ether-phenyl-ketone-phenyl-ketone-phenyl, -ether-diphenyl-ether-phenyl-sulfone-phenyl, -ether-phenyl-ether-phenyl-sulfone-phenyl, or ether-phenyl-sulfone-phenyl. Preferably, the second unit is -ether-phenyl-ketone-phenyl-ketone-phenyl, ether-phenyl-ether-phenyl-ketone-phenyl-ketone-phenyl, -ether-phenyl-ether-phenyl-ketone-phenyl, -ether-phenyl-ketone-phenyl-, -ether-phenyl-ketone-phenyl-ether-phenyl-ketone-phenyl-ketone-phenyl, or -ether-biphenyl-ether-phenyl-ketone-phenyl-. Preferably, the third unit is ether-phenyl-sulfone-phenyl, ether-phenyl-ether-phenyl-sulfone-phenyl, or 1,3-dioxy-4-(phenylcarbonyl)phenyl moiety.Z = aromatic group containing moiety EXAMPLE - 4,4'-Difluorobenzophenone (89.03 g), 4,4'-dihydroxybiphenyl (37.24 g), 4,4'-dihydroxydiphenylsulfone (10.01 g), 4,4'-dihydroxybenzophenone (34.28 g), and diphenylsulfone (332 g) were charged in a flask and purged with nitrogen for 1 hour. The contents were heated at 140-150degreesC to form a colorless solution. Dried sodium carbonate (43.24 g) was added and the temperature was raised gradually to 320degreesC for 3 hours then maintained for 1.5 hours. The mixture was allowed to cool, milled, and washed with acetone and water. The resulting polymer was dried at 120degreesC, and sulfonated in 98% sulfuric acid. The product was dissolved in N-methylpyrrolidone at 80degreesC. The solution was cast on a glass plate to give 400-mum films. Solvent was evaporated at 100degreesC under vacuum for 24 hours.