Laser‐induced periodic surface structure on a polymer surface: The effect of a prerubbing treatment on the surface structure

Abstract

The influence of the mechanical rubbing of a polyimide (PI) film on the laser-induced periodic structure (LIPS) was demonstrated. The periodicity and amplitude of LIPS were greater when the rubbing direction was parallel to the laser polarization direction. The amplitude became small and the periodicity of LIPS did not show an obvious change when the rubbing direction was perpendicular to the laser polarization direction. The effect of the rubbing pretreatment on LIPS was explained on the basis of the wave-guide effect of rubbing-induced microgrooves on LIPS formation. The orientation of PI chains induced by mechanical rubbing was relaxed after laser irradiation, and a new orientation of PI chains was formed during the LIPS formation. When the rubbing direction was perpendicular to the laser polarization direction, the orientation of PI chains remained in the rubbing direction. The laser-irradiated, perpendicularly rubbed PI surface could be used to verify the effects of surface morphologies and intermolecular interactions on liquid-crystal alignment.

New photochromic polyimides

“…Dianhydrides have been synthesized by the esterification of trimellitic anhydride chloride and diols [35]. Diol (10 mmol) and pyridine (1.2 mmol) in 25 ml of acetone have been added dropwise to the solution of trimellitic anhydride chloride (15 mmol) in 25 ml of acetone.…”

Re-Writable Multi-Domain Liquid Crystal Alignment Layers through Laser-Induced Micropatterning

“…PI was synthesized from 4,4 0 -diamino-3,3 0 -diphenylmethane and benzophenone-3,3 0 ,4,4 0 -tetracarboxylic dianhydride. 17) The PI films were prepared by spin-coating a Nmethyl-2-pyrrolidone solution of PI (10 wt %) onto glass substrates and then being dried at 80 C for 30 min and 100 C for 2 h. 18) The coated films were about 0.7 -0.8 mm thick according to the ellipisometry measurement. The third harmonic generation of an s-polarised Nd:YAG laser (355 nm) was used to induce the LIPSS on the PI films with an energy density of 14 mJ/cm 2 , a pulse duration of 5 ns and repetition rate of 10 Hz.…”