| Summary: | 碩士 === 中原大學 === 化學研究所 === 105 === In this research work, cholesteric liquid crystal (CLC) containing a nematic liquid crystal dispersed with one or two different chiral dopant and polymer stabilized cholesteric liquid crystal (PSCLC) were investigated. Further, One type of PSCLC/inorganic layered material nanocomposites has been synthesized by using electrochromic PSCLC, including nematic liquid crystal E7, left-hand twist (LT) chiral dopant S811, right-hand twist (RT) chiral dopant R5011, photocurable monomer NOA65 and inorganic layered materials. The inorganic layered materials are classified into natural layered clay material and synthetic layered double hydroxides (LDHs). The electroactive Pentamerous oligo- aniline (POA) used as a organo modifier for natural inorganic layered materials modification. The small amount of inorganic layered materials are doped into the PSCLC. The effects, which were caused by time of polymerization, intensity of polymerization and the concentration of photo- curable monomer on PSCLC were also investigated. The morphology and structural identification of organo modified inorganic layered materials identified by Wide Angle X-Ray Diffraction (WXRD), Fourier Transform Infrared (FT-IR) and Thermo- gravimetry Analyzer (TGA). PSCLC optical properties including threshold voltage, drive voltage, response time under 1 kHz AC electric field measured. The colour and morphology change of inorganic layered materials doped PSCLC observed by Polarizing Optical Microscope (POM) at different applied voltage. According to the experimental results, it was found that PSCLC had a lower threshold voltage or driving voltage with a lower concentration of photocurable monomer, PSCLC (RS/2.5) showed the lower intensity of polymerization about 2.2 mW/cm2 for 10 minutes. The PSCLC (RS/2.5) without doped natural layered clay and with doped CL42, CL120, CL88 driving voltage were 77.3, 74.6, 82.9 and 96.3 Vrms, respectively. It was found that CL42 doped PSCLC (RS/2.5) can effectively provide reducing the driving voltage. The PSCLC (RS/2.5) without doped LDHs and with doped MgAl-LDH、ZnAl-LDH、LiAl-LDH the driving voltage were 77.3、71.0、77.5 and 84.8 Vrms, respectively. It shown that MgAl-LDH in PSCLC (RS/2.5) can effectively reduce the driving voltage. The faster response time of CL42 (3.75 ms) and MgAl-LDH (4.31 ms) the better reducing the driving voltage. The phase transition temperature of cholesteric phase measured by differential scanning calorimetry (DSC), the CLC containing chiral dopant R5011 with helical twisting power (HTP) had wide temperature range for cholesteric phase and good in temperature stability, increasing from 39°C to 56.18°C. Additionally, CL42 doped PSCLC (R/2.5), the driving voltage decreased slightly from 76.6 Vrms to 76.1 Vrms with the increase of the CL42 doping amount, and the response time effectively reduced about 42.6% (105.55 ms to 60.6 ms) under 75 Vrms. It is proved that due to doped inorganic material CL42 can increase the crystallinity of liquid crystal and suppress the ionic impurities. Hence, resulting the optical properties of PSCLC can be improved in driving voltage and response time. In addition, from POM analysis, it is observed that natural clay PSCLC (RS/2.5)-CL120 and modified clay PSCLC (R/2.5)-CL120-POA, PSCLC (R/2.5)-CL42-POA showes the aggregation morphology. Thus it’s make the driving voltage can’t effectively improve. The stability test shows that CLC (R/2.5)-CL42 1.0 phr has a more stable state result, the stability deviation from 1.8 to 0.7 Vrms.
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