Zli 811

The left-handed chiral microparticles are prepared through the following steps. First, a pure reactive mesogen contained in RMS03-001C blend (Merck, Germany) is obtained extracting its solvent PGMEA (propylene glycol monomethyl ether acetate) by vacuum evaporation at 90 °C. Thus, this is mixed with a left-chiral dopant (ZLI-811, Merck) at concentration of 23% wt. yielding a CLC phase. Then, a CLC droplet emulsion is prepared with type I ultrapure water (18.2 MΩ cm resistivity at 25 °C, < 5 ppb total organic carbon). The values of the extraordinary and ordinary refractive indices of the reactive mesogen at 500 nm are respectively n_// = 1.68 and n_⊥ = 1.53. The emulsion is polymerized in nitrogen environment for at least 4 hours under a 2 mW cm⁻² intensity UV lamp (Mega Electronics lamp mod. LV202-E) having emission wavelength centred at 350 nm. The size of the solid chiral particles produced by this method ranges from hundreds of nanometres up to tens of microns. The resulting helicoidal pitch p, is approximately 0.3 μm. Finally, a few tens of microliters of the chiral particles suspension are loaded in a small glass chamber for OT experiments.

LC monomers 4-[[[4-[(1-Oxo-2-propenyl)oxy]butoxy]carbonyl]oxy]benzoic
acid 2-methyl-1,4-phenylene ester (LC242) and 4-Methoxybenzoic acid
4-(6-acryloyloxy-hexyloxy)phenyl ester (C6BP) were acquired from BASF
and Synthon, respectively. Photoinitiator camphorquinone (CQ) was
purchased from ABCR. Co-initiator ethyl 4-(Dimethylamino)benzoate
(EDAB) and photoinhibitor 2,2′-Bis(2-chlorophenyl)-4,4′,5,5′-tetraphenyl-1,2′-biimidazole
(o-Cl-HABI) were obtained from TCI. Chiral dopant
benzoic acid, 4-hexyl-,4-[[(1-methylheptyl)oxy]carbonyl]phenyl ester
(ZLI-811), was acquired from Merck.
Coatings used for cell preparation
included OPTMER AL 1254 from JSR (planar alignment), Sunever 5661
from Nissan Chemical (homeotropic alignment), 3-(trimethoxysilyl)propyl
methacrylate (adhesive coating), and trimethoxy(octadecyl)silane (antiadhesive
coating) from Sigma-Aldrich.
The developer solution comprised
isopropyl alcohol (IPA) from Biosolve,
propylene glycol monomethyl ether acetate (PGMEA) from Aldrich, and
methyl isobutyl ketone (MIBK) from Acros Organics. Dichloromethane
(DCM) and tetrahydrofuran (THF) were purchased from Biosolve.