We report uniform and homogeneous liquid crystal (LC) alignment using ion beam (IB)-irradiated poly(styrene-maleic anhydride) (SMA) films as an alignment layer when the IB incidence angle is controlled. The molecular polarity on the SMA surface increased with IB irradiation, especially at an incidence angle of 30 degrees, resulting in strong van der Waals forces between the LC molecules and the surface. Atomic force microscopy and X-ray photoelectron spectroscopy were used to determine the LC alignment mechanism. Chemical structure analysis indicated that the orientation of LC molecules was due to van der Waals forces and selective breaking of C-C bonds by IB irradiation. The potential application of SMA substrates as alignment layers for display devices was further supported by their higher thermal stability (220 degrees C) compared with that of conventional rubbed SMA (160 degrees C) and rubbed polyimide (160 degrees C). Therefore, LC cells with IB-irradiated SMA are potential candidates for alternative alignment layers in LC applications. (C) 2017 Elsevier B.V. All rights reserved.