Poly(amide-imide) copolymer, composition for preparing poly(amide-imide) copolymer, article including poly(amide-imide) copolymer, and display device including the article

A composition for preparing a poly(amide-imide) copolymer comprising a substituted or unsubstituted linear aliphatic diamine, a compound represented by Chemical Formula 4, and a tetracarboxylic acid dianhydride comprising a combination of a compound represented by Chemical Formula 3-1 and a compound represented by Chemical Formula 3-2, and a solvent:

• wherein, in Chemical Formula 4,
• R3 is a substituted or unsubstituted phenylene or a substituted or unsubstituted biphenylene group,
• n0 is a number greater than or equal to 1, and
• Ar1 and Ar2 are each independently represented by Chemical Formula 5:
• wherein, in Chemical Formula 5,
• R6 and R7 are each independently an electron withdrawing group selected from —CF3, —CCl3, —CBr3, —Cl3, —NO2, —CN, —C(═O)CH3, and —CO2C2H5,
• R8 and R9 are each independently a halogen, a hydroxy group, a substituted or unsubstituted C1 to C10 aliphatic organic group, a substituted or unsubstituted C6 to C20 aromatic organic group, an alkoxy group of formula —OR204, wherein R204 is a C1 to C10 aliphatic organic group, or a silyl group of formula —SiR205R206R207 wherein —R205, R206, and R207 are each independently hydrogen or a C1 to C10 aliphatic organic group,
• n3 is an integer ranging from 1 to 4, n5 is an integer ranging from 0 to 3, provided that n3+n5 is an integer ranging from 1 to 4, and
• n4 is an integer ranging from 1 to 4, n6 is an integer ranging from 0 to 3, provided that n4+n6 is an integer ranging from 1 to 4;