Flexible plastic substrate and display device including same

A flexible plastic substrate comprising

• a film comprising a poly(amide-imide) copolymer;
• and
• a hard coating layer disposed on a first surface of the film,
• wherein the hard coating layer comprises a crosslinked siloxane copolymer wherein the crosslinked siloxane copolymer comprises a cured product of a siloxane copolymer represented by at least one of Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3:
• (R1SiO3/2)x(R2R3SiO2/2)y Chemical Formula 1
• wherein, in Chemical Formula 1,
• R1 is a cross-linkable functional group or a hydrocarbyl group substituted with a cross-linkable functional group,
• R2 and R3 are each independently hydrogen, a cross-linkable functional group, a hydrocarbyl group substituted with a cross-linkable functional group, a substituted or unsubstituted C1 to C20 alkyl group, or a substituted or unsubstituted C5 to C20 cycloalkyl group, provided that at least one of R2 and R3 is a substituted or unsubstituted C1 to C20 alkyl group, and
• 0<x<1, 0<y<1, and x+y=1,
• (R1SiO3/2)x(R4SiO3/2)z Chemical Formula 2
• wherein, in Chemical Formula 2,
• R1 is a cross-linkable functional group or a hydrocarbyl group substituted with a cross-linkable functional group;
• R4 is an ultraviolet light absorbing functional group or a C1 to C20 hydrocarbyl group substituted with an ultraviolet light absorbing functional group;
• and
• 0<x<1, 0<z<1, and x+z=1,
• (R1SiO3/2)x(R2R3SiO2/2)y(R4SiO3/2)z Chemical Formula 3
• wherein in Chemical Formula 3,
• R1 is a cross-linkable functional group or a hydrocarbyl group substituted with a cross-linkable functional group;
• R2 and R3 are each independently hydrogen, a cross-linkable functional group, a hydrocarbyl group substituted with a cross-linkable functional group, a substituted or unsubstituted C1 to C20 alkyl group, or a substituted or unsubstituted C5 to C20 cycloalkyl group, provided that at least one of R2 and R3 is a substituted or unsubstituted C1 to C20 alkyl group;
• R4 is an ultraviolet light absorbing functional group or a C1 to C20 hydrocarbyl group substituted with an ultraviolet light absorbing functional group;
• and
• 0<x<1, 0<y<1, 0<z<1, and x+y+z=1, and
• wherein the flexible plastic substrate has
• a pencil hardness of greater than or equal to 2H under a vertical load of 1 kilogram according to ASTM D3363,
• a total light transmittance of greater than or equal to about 89% in a wavelength region of 350 nanometers to 750 nanometers.