Novel poly(amide imide)s containing functional nitrile groups were prepared by one step polycondensation reaction of two new diacid chlorides having nitrile substituents with various aromatic diamines incorporating flexible ether bridges. The polymers were readily soluble in polar organic solvents such as N-methylpyrrolidinone, N,N-dimethylformamide, dimethylsulfoxide, and were processed into thin films from such solutions. Most of these polymers showed high thermal stability with decomposition temperature being above 390 degrees C and glass transition temperature in the domain of 190-220 C. The molecular relaxations in polymer films were evidenced by dynamic mechanical analyses and dielectric spectroscopy. The electrostrictive nano-actuation of polymer films was determined using an experimental setup for linear measurements, based on a Michelson type interferometer. Also the film surface with specific profiles was investigated using an optical interferometric microscope. (C) 2011 Elsevier Ltd. All rights reserved.