A monomer represented by Chemical Formula 3: wherein in Chemical Formula 3, L 1 and L 2 are independently O or NH, A 1 and A 2 are independently benzene, pentalene, pyrazole, imidazole, thiazole, triazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, indazole, indolizine, benzimidazole, benzthiazole, benzothiophene, benzopurine, isoquinoline, or purine, p and q are independently an integer ranging from 0 to 20, o and r are independently an integer ranging from 0 to 3, and R 1 and R 2 are independently a group represented by Chemical Formula 2, hydrogen, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C1 to C30 alkoxy group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C3 to C30 cycloalkoxy group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C2 to C30 heteroaryl group, a substituted or unsubstituted C7 to C30 arylalkyl group, a hydroxy group, a halogen, a nitro group, -NR'R", -CO-NR'R", or -SiR'R"R"' wherein R', R", and R"' are independently hydrogen, a C1 to C30 alkyl group, a C6 to C30 aryl group, or a C7 to C30 arylalkyl group: wherein in Chemical Formula 2, L 3 and L 4 are independently O, CO, COO, C=C, or CONR b wherein R b is hydrogen or a C1 to C30 alkyl group, A 3 and A 4 are independently a substituted or unsubstituted C6 to C30 aromatic ring, a substituted or unsubstituted fluorene ring, a substituted or unsubstituted C7 to C30 arylalkyl group, or a substituted or unsubstituted C3 to C30 hetero aromatic ring group, and s and t are independently an integer ranging from 0 to 3. L 1 and L 2 are independently O or NH, A 1 and A 2 are independently benzene, pentalene, pyrazole, imidazole, thiazole, triazole, pyridine, pyridazine, pyrimidine, pyrazine, triazine, indazole, indolizine, benzimidazole, benzthiazole, benzothiophene, benzopurine, isoquinoline, or purine, p and q are independently an integer ranging from 0 to 20, o and r are independently an integer ranging from 0 to 3, and R 1 and R 2 are independently a group represented by Chemical Formula 2, hydrogen, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C1 to C30 alkoxy group, a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C3 to C30 cycloalkoxy group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C2 to C30 heteroaryl group, a substituted or unsubstituted C7 to C30 arylalkyl group, a hydroxy group, a halogen, a nitro group, -NR'R", -CO-NR'R", or -SiR'R"R"' wherein R', R", and R"' are independently hydrogen, a C1 to C30 alkyl group, a C6 to C30 aryl group, or a C7 to C30 arylalkyl group: wherein in Chemical Formula 2, L 3 and L 4 are independently O, CO, COO, C=C, or CONR b wherein R b is hydrogen or a C1 to C30 alkyl group, A 3 and A 4 are independently a substituted or unsubstituted C6 to C30 aromatic ring, a substituted or unsubstituted fluorene ring, a substituted or unsubstituted C7 to C30 arylalkyl group, or a substituted or unsubstituted C3 to C30 hetero aromatic ring group, and s and t are independently an integer ranging from 0 to 3. L 3 and L 4 are independently O, CO, COO, C=C, or CONR b wherein R b is hydrogen or a C1 to C30 alkyl group, A 3 and A 4 are independently a substituted or unsubstituted C6 to C30 aromatic ring, a substituted or unsubstituted fluorene ring, a substituted or unsubstituted C7 to C30 arylalkyl group, or a substituted or unsubstituted C3 to C30 hetero aromatic ring group, and s and t are independently an integer ranging from 0 to 3.