Colorfully Patterned Epoxy Resin Films with a Cholesteric Structure Prepared through a Photopolymerization Approach

Abstract

Structurally colored epoxy resin films were prepared using a liquid crystalline (LC) epoxy monomer of E11M and a chiral additive of CA-iso through a photopolymerization approach. With the addition of the co-photoinitiator isopropyl thioxanthone and comonomer 3′,4′-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, the polymerization rate was increased. Since the epoxy resin films can be obtained within several seconds, they are feasible for large-area preparation on the coating line. The reflective wavelength was tunable by changing the concentration of CA-iso in the LC mixture. Diffuse-reflectance circular dichroism spectra indicated a right-handed helical supramolecular structure. Field-emission scanning electron microscopy images indicated a multilayer structure. Since the LC mixtures were thermochromic, colorfully patterned epoxy resin films were prepared by controlling the polymerization temperature. Moreover, LC gratings were also prepared, which were expected to be applied for anticounterfeiting.

Low dielectric constant and highly intrinsic thermal conductivity fluorine‐containing epoxy resins with ordered liquid crystal structures

“…In contrast, there is only an exothermic peak at 196.0°C during the heating process of TFSAEy. This is because the temperature of the liquid crystal phase transition for TFSAEy is higher than the reaction temperature between the amino groups and the epoxy groups, gradually generating the cross‐linking curing reaction of TFSAEy during the heating process 36 . Therefore, the observation region of TFSAEy under POM shows yellow bright spots (Figure 3I1–I3) before the exothermic peak.…”

“…This is because the temperature of the liquid crystal phase transition for TFSAEy is higher than the reaction temperature between the amino groups and the epoxy groups, gradually generating the cross-linking curing reaction of TFSAEy during the heating process. 36 Therefore, the observation region of TFSAEy under POM shows yellow bright spots (Figure 3I1-I3) before the exothermic peak. When the temperature is further increased, the color of the observed region gradually deepens, and the yellow bright spots do not disappear (Figure 3I4-I6).…”

Structural coloured epoxy resin patterns prepared using thermochromic epoxy liquid crystal mixtures

“…8,44 Moreover, the double-layered interpenetrating CLCN films were prepared using acrylate and oxetane monomers through polymerization-induced phase separation. 37 Recently, it was reported by our group that the CLCN patterns can be prepared using nematic epoxy liquid crystals with the addition of chiral dopants. 37,45 These patterns are potentially applied for decoration and anti-counterfeiting.…”

Polymer-Stabilized Cholesteric Liquid Crystal Films with Double Reflection Bands Prepared Based on the Competition between Photopolymerization and Photoisomerization

“…Reactive CLC mixtures were generally prepared using nematic liquid crystals (LCs) and chiral dopants. To fix the structural color, several kinds of polymer-stabilized CLC (PSCLC) films were prepared, including polyacrylates, 24−50 epoxy 51,52 and oxetane resins, 53,54 polysiloxanes 55,56 and organic−inorganic hybrid silicas. 57−59 The structural color was controlled by changing the concentration of the chiral dopant or the polymerization condition.…”

“…Reactive CLC mixtures were generally prepared using nematic liquid crystals (LCs) and chiral dopants. To fix the structural color, several kinds of polymer-stabilized CLC (PSCLC) films were prepared, including polyacrylates, − epoxy , and oxetane resins, , polysiloxanes , and organic–inorganic hybrid silicas. − The structural color was controlled by changing the concentration of the chiral dopant or the polymerization condition. These films can be used in optics, , sensors, − displays, decoration , and anti-counterfeiting. , For the preparation of PSCLC films with double reflection bands, several methods have been developed.…”