For the FT-IR measurements, two samples were prepared with the monomers 4,4′-DMOB and 3,3′-DMOB in 5CB. First, 0.5 wt% of the monomer (4,4′-DMOB or 3,3′-DMOB) was dissolved in 5CB. Each solution was sonicated to a mixture; then, 1 g of each mixture was deposited on a glass substrate. For the polymerization, two samples were exposed to UV light with the light source of FHF-32BLB (Toshiba, Japan) at 35 °C. After 10 min of UV light exposure, white precipitates were obtained. The precipitates obtained from each sample were cleaned with acetone, filtered and dried for 12 h at 35 °C before the FT-IR measurements.

For the liquid chromatography, SEM and POM evaluations, other samples were prepared as follows. First, a polyamic acid solution was spin-coated on the substrates and baked at 200 °C for 60 min to form a polyimide layer. The polymers produced from the monomers in the LC are effectively adsorbed on the surface of the polyimide layer.15 Then, each polyimide layer was rubbed to produce an anti-parallel alignment, the substrates were assembled and each mixture of 5CB and monomer was injected. Finally, the samples were exposed to UV light at 35 °C for 2, 4, 6, 8 and 10 min. For comparison, other samples were also prepared by exposing to UV light at 50 °C for 1, 2, 3 and 4 min. After the samples decomposed, 5CB with residual monomer was dissolved in acetonitrile for the liquid chromatography measurements. Moreover, the substrates were placed in hexane for 90 min to remove 5CB. For the SEM observation, osmium was coated onto the substrates.

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