| 主权项 |
1. A poly(amide-imide) copolymer comprising
a structural unit represented by Chemical Formula 1; a structural unit represented by Chemical Formula 2 and/or an amic acid precursor structural unit which forms the structural unit represented by Chemical Formula 2 through imidization; and a structural unit represented by Chemical Formula 3 and/or an amic acid precursor structural unit which forms the structural unit represented by Chemical Formula 3 through imidization: wherein in Chemical Formula 1, R5 is the same or different in each structural unit, and is each independently a substituted or unsubstituted C6 to C30 aromatic organic group, wherein the C6 to C30 aromatic organic group comprises two or more aromatic rings, wherein the two or more aromatic rings are fused together to provide a condensed ring system, or wherein the two or more aromatic rings are connected through a single bond or through a functional group selected from a fluorenylene group, O, S, C(═O), CH(OH), S(═O)2, and a combination thereof, R6 and R7 are the same or different and are each independently an electron withdrawing group selected from —CF3, —CCl3, —CBr3, —Cl3, —F, —Cl, —Br, —I, —NO2, —CN, —COCH3, and —CO2C2H5; R8 and R9 are the same or different, and are each independently a halogen, a hydroxy group, a substituted or unsubstituted C1 to C10 aliphatic organic group, a 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 the same or different and 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, 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. wherein in Chemical Formula 2 or 3, R10 is the same or different in each structural unit, and is each independently a substituted or unsubstituted C1 to C30 aliphatic organic group, a substituted or unsubstituted C3 to C30 alicyclic organic group, a substituted or unsubstituted C6 to C30 aromatic organic group, or a substituted or unsubstituted C2 to C30 heterocyclic group, R11 is the same or different in each structural unit, and each independently comprises a substituted or unsubstituted C6 to C30 aromatic organic group, wherein the C6 to C30 aromatic organic group is a single aromatic ring, two or more aromatic rings fused together to provide a condensed ring system, or two or more moieties independently selected from the single aromatic ring and two or more aromatic rings fused together to provide a condensed ring system, which are connected through a single bond or through a functional group selected from a fluorenylene group, O, S, C(═O), CH(OH), S(═O)2, Si(CH3)2, (CH2)p wherein 1≦p≦10, (CF2)q wherein 1≦q≦10, C(CH3)2, C(CF3)2, C(═O)NH, and a combination thereof; R12 and R13 are the same or different, and are each independently a halogen, a hydroxy group, a substituted or unsubstituted C1 to C10 aliphatic organic group, a C6 to C20 aromatic organic group, an alkoxy group of formula —OR208, wherein R208 is a C1 to C10 aliphatic organic group, or a silyl group of formula —SiR209R210R211, wherein R209, R210, and R211 are the same or different, and are each independently hydrogen or a C1 to C10 aliphatic organic group, and n7 and n8 are each independently integers ranging from 0 to 3, wherein the poly(amide-imide) copolymer has a modulus of greater than or equal to about 5.5 giga Pascals after being cured, a yellowness index YI of less than or equal to about 3.5, and an increase in yellowness index ΔYI of less than or equal to about 0.7 after being exposed to ultraviolet light for 72 hours. |
