Polyethylene imines having nitro substituent azobenzene side chain group with different methylene spacer groups (PEImN) were successfully synthesized and characterized by differential scanning calorimetry, polarized optical microscopic, and X-ray diffraction analysis. All synthesized polyethylene imines showed liquid crystalline properties and the glass transition temperature (Tg) of PEImN decreased as the number of methylene spacers increased. Melting temperatures (Tm) of synthesized PEImN showed an odd-even effect. Photochemical, thermo-optical, as well as photo alignment behavior of PElmN were investigated and out-of-plane orientational behavior of polymeric films was dependent on number of methylene spacers and polyethylene imines having higher number of methylene spacers (six or more) showed high order parameter values that revealed the well pronounced tendency for the development of out-of-plane order from random state on annealing. And the molecular orientation of PEImN between random and out-of-plane structures has been achieved by the combination of thermal and photochemical processes. (C) 2010 Wiley Periodicals, inc. J Appl Polym Sci 120: 950-959, 2011