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

1. A poly(amide-imide) copolymer prepared from reactants that consist of a diamine represented by Chemical Formula 1, a diamine represented by Chemical Formula 2, a dicarbonyl compound represented by Chemical Formula 3, and a tetracarboxylic acid dianhydride:

wherein in Chemical Formula 1,

R a is a substituted or unsubstituted C1 to C4 alkyl group, L 2 is a single bond, and L 1 is a substituted or unsubstituted C1 to C10 alkylene group, and

n1 is an integer ranging from 1 to 3;

NH 2 -A-NH 2   Chemical Formula 2

wherein in Chemical Formula 2,

A is represented by Chemical Formula 6:

wherein, in Chemical Formula 6,

R 8 and R 9 are each independently a halogen or C1-C2 haloalkyl,

n3 is 0, n5 is an integer ranging from 1 to 3, and

n4 is 0, n6 is an integer ranging from 1 to 3;

wherein an amount of the diamine represented by Chemical Formula 1 accounts for 10 mole percent to 25 mole percent based on the total amount of the diamine represented by Chemical Formula 1 and the diamine represented by Chemical Formula 2;

wherein, in Chemical Formula 3,

R 3 is a substituted or unsubstituted phenylene group or a substituted or unsubstituted biphenylene group, and

each X is an identical or different halogen atom;

wherein the tetracarboxylic acid dianhydride comprises at least one of 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA),

3,3′,4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA),

4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), or 4,4′-oxydiphthalic anhydride (ODPA); and

wherein a mole ratio of the dicarbonyl compound represented by Chemical Formula 3 and the tetracarboxylic acid dianhydride 4 is 30 to 70:70 to 30.

2. The poly(amide-imide) copolymer according to claim 1 , wherein the diamine represented by Chemical Formula 2 comprises at least one of the diamines represented by chemical formulae:

3. The poly(amide-imide) copolymer according to claim 1 , wherein the diamine represented by Chemical Formula 2 comprises a diamine represented by Chemical Formula A:

4. The poly(amide-imide) copolymer according to claim 1 , wherein in Chemical Formula 3, R 3 is a phenylene group, and each X is independently Cl or Br.

5. The poly(amide-imide) copolymer according to claim 1 , wherein the tetracarboxylic acid dianhydride comprises a combination of 3,3′,4,4′-biphenyl tetracarboxylic dianhydride and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride.

6. The poly(amide-imide) copolymer according to claim 1 , wherein the mole ratio of the dicarbonyl compound represented by Chemical Formula 3 and the tetracarboxylic acid dianhydride is from 50:50 to 60:40.

7. A composition for preparing a poly(amide-imide) copolymer consisting of a diamine represented by Chemical Formula 1, a tetracarboxylic acid dianhydride, and a compound represented by Chemical Formula 5:

wherein, in Chemical Formula 1,

R a is a substituted or unsubstituted C1 to C4 alkyl group;

L 2 is a single bond, and L 1 is a substituted or unsubstituted C1 to C10 alkylene group, and

n1 is an integer ranging from 1 to 3;

wherein the tetracarboxylic acid dianhydride comprises at least one of 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA),

3,3′,4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA),

4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), or 4,4′-oxydiphthalic anhydride (ODPA);

wherein, in Chemical Formula 5,

R 3 is a substituted or unsubstituted phenylene group or a substituted or unsubstituted biphenylene group,

n0 is an integer ranging from 1 or more, and

Ar 1 and Ar 2 are each independently represented by Chemical Formula 6:

wherein, in Chemical Formula 6,

R 8 and R 9 are each independently a halogen or C1-C2 haloalkyl,

n3 is 0, n5 is an integer ranging from 1 to 3, and

n4 is 0, n6 is an integer ranging from 1 to 3;

wherein Ar 1 and Ar 2 are each independently derived from a diamine represented by Chemical Formula 2:

NH 2 -A-NH 2   Chemical Formula 2

wherein in Chemical Formula 2,

A is represented by the above Chemical Formula 6; and

wherein an amount of the diamine represented by Chemical Formula 1 accounts for 10 mole percent to 25 mole percent based on the total amount of the diamine represented by Chemical Formula 1 and the diamine represented by Chemical Formula 2, and the amount of the diamine represented by Chemical Formula 2 is the amount required for preparing the compound represented by Chemical Formula 5.

8. The composition for preparing a poly(amide-imide) copolymer according to claim 7 , wherein the tetracarboxylic acid dianhydride represented by Chemical Formula 4 consists of a combination of 3,3,4,4-biphenyl tetracarboxylic dianhydride (BPDA), and

4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA).

9. An article comprising a poly(amide-imide) copolymer according to claim 1 .

10. The article according to claim 9 , wherein the article comprises a film, wherein the film has a light transmittance of greater than or equal to 88.8 percent (%) in a wavelength range from 350 nanometers (nm) to 750 nanometers, a yellowness index (YI) of less than 2, a refractive index of less than 1.7, and a tensile modulus of greater than or equal to 5 GPa.

11. A display device comprising the article according to claim 9 .

12. The poly(amide-imide) copolymer according to claim 1 , wherein the diamine represented by Chemical Formula 1 is isophorone diamine.

13. The composition for preparing a poly(amide-imide) copolymer according to claim 7 , wherein the diamine represented by Chemical Formula 1 is isophorone diamine.