Adjustable pretilt angle of nematic 4- n -pentyl- 4 ′ -cyanobiphenylon self-assembled monolayers formed from organosilaneson square-wave grating silica surfaces

The square-wave grating silica surfaces are fabricated by soft embossing silica sol-gel precursor on glass substrates with an elastomeric polydimethylsiloxane mold. The patterned silica surface could induce the planar alignment of liquid crystal 4- n -pentyl- 4 ′ -cyanobiphenyl (5CB) along the direction of microgrooves but with no pretilt angle. The pretilt angle of 5CBs is adjusted from 0° to 90° by the further deposition of organosilane self-assembled monolayers with different functional end-groups on the patterned silica surfaces.