Optical Second Harmonic Generation Study of a Rubbed Polyimide Film Containing Steroidal Structure Side Chains

Abstract

We have studied the optical second harmonic generation (SHG) of a rubbed novel polyimide (PI) film having steroidal structure side chains prepared by spin coating on an indium tin oxide (ITO)-coated glass substrate. The second order nonlinear susceptibility χ_ijk⁽²⁾ elements were obtained from the fitting of the SHG data. The symmetry of the polymer chains roughly belonged to Cs symmetry with the rubbing direction parallel to the mirror plane. The average polar (tilt) angle of the rubbed PI chains was determined to be around 16° by using the measured χ_ijk⁽²⁾ elements. [DOI: 10.1380/ejssnt.2017.7]