For the development of anisotropic thermal interface materials (TIMs), a rod-shaped reactive monomer PNP-6MA is newly designed and successfully synthesized. PNP-6MA reveals a smectic A (SmA) mesophase between crystalline (K) and isotropic (I) phases. PNP-6MA can be oriented under a magnetic field ( B = 2 T), and its macroscopic orientation can be robustly stabilized by in situ polymerization. Even without macroscopic orientations, the fabricated thermal conducting liquid crystal (TCLC) films show the outstanding thermal conductivity of 1.21 W/m K, which is higher than conventional organic materials. The thermal conductivity of uniaxially and macroscopically oriented TCLC films can be 2.5 W/m K along the long axis of mesogenic core. The newly developed TCLC film can be used as a TIM between a high-power light-emitting diode and a heat sink.
Solid-state luminescence is an important strategy for color generation via molecular self-assembly. Here, a new luminogen (AT 3 EMIS) containing both a rigid chromophore and a flexible dendron is designed and synthesized for multicolor emission. The emission energy of the target material is precisely controlled by adjusting three different columnar arrays through thermal and mechanical stimulation. With well-defined supramolecular organizations in different length scales, the luminescent properties of the light switch can be tuned.
Bandwidth-tunable anisotropic spatial light modulators are fabricated with redox-responsive dichroic mesogens. By introducing an ionic group and a polymerizable group into the chromophore, the programmed reactive mesogen (PDI-MA) exhibits a lyotropic chromonic liquid crystal (LCLC) phase. The PDI-MA molecule forms a stable aromatic dianion state so that the absorption wavelengths of the dichroic mesogen can be reversibly tuned by redox reactions. Through a continuous process of coating, molecular self-assembly, and polymerization, redoxresponsive and uniaxially oriented LCLC polymer films are fabricated. Because of the high dichroic ratio of PDI-MA, the uniaxially oriented LCLC network is capable of anisotropic light modulation in the visible-light spectrum. Uniaxially oriented LCLC films are applied to flexible multichromic smart windows and optical security filters for anticounterfeiting.
A self-crosslinkable side-chain liquid crystal polysiloxane containing cyanostilbene (Si-CSM) is newly synthesized for a new generation of flexible optical paints. The photoisomerization of cyanostilbene moiety at the molecular level is...
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