Side-chain liquid-crystalline copolymers and polymer blends containing an electron-donating (carbazolylmethylene)aniline group and electron-accepting nitrophenyl groups with various central linking groups between aromatic groups in the mesogenic units, i.e., N = CH, CH = CH, N = N, and COO, were prepared to examine effects of the mesogenic structure on thermal behaviors. The most remarkable effects of the central linking group on the thermal properties and the miscibility were observed for the polymer blends. The 1:1 miscible polymer blends were prepared from the electron-donating polymer containing (carbazolylmethylene)aniline group (PM6Cz) and the electron-accepting polymers with similar central linking groups, i.e., N = CH, CH = CH, and N = N. For example, the 1:1 polymer blend of PM6Cz and the electron-accepting polymer containing the nitrostilbene group induced a smectic phase from 73 to 207 degrees C. This isotropic temperature was 46 degrees C higher than the calculated value (161 degrees C) based on the composition without the electron donor-acceptor interaction. On the other hand, the 1:1 polymer blend of PM6Cz and the electron-accepting polymer containing the nitrophenylbenzoate group showed phase separation. Thus, the remarkable thermal stability and the miscibility of the polymer blends containing the electron donor and acceptor groups might be caused by planar structures between the mesogenic side groups which have similar central linking groups through the electron donor-acceptor interaction. A similar tendency was seen for copolymers and binary mixtures of both low-molecular-weight compounds containing the same mesogenic groups.