Polymerization of Diacrylate Mesogen in an Interference Field

Autor: Meng-Yao Su, 蘇盟堯
Rok vydání: 2014
Druh dokumentu: 學位論文 ; thesis
Popis: 102
Mesogenic diacrylate, RM257、RM82, kinds of main chain liquid crystal polymers (MCLCPs) and light-sensitive materials. In our past research, two kinds of laser light source induced the diacrylate mesogen polymerization was discovered. We calculated the two-photo absorption coefficients by the transmission against intensity of mesogenic diacrylate. Through none- linear optical measurement, Z-scan, the reverse saturable absorption curve was observed near phase-transition temperature. According to the TPA (two-photo absorption) coefficient and NLO (none-linear absorption) effect, two-photo absorption progress to induce polymerization was confirmed. Base on the above characteristics, two –beam interference field with s-polarized was applied to form a periodic grating on mesogenic diacrylate. Some stripes of the grating oriented were observed. In this study, phase-retardation method was applied to identify the director of the grating. In addition, experiments to make sure the interference field; destructive field and constructive field each represent the stripes dark or bright of grating in POM (polarizing optical microscope) observing. As we know the polymerization time of light source of He-Ne laser (one beam) irradiating to the RM82 cells. Compare to laser, broad-band light source(λ>550 nm) also induced polymerization of RM82 but spending more time. That is, there is much higher probability for laser light source than broad-band light source to cause TPA. Pre-aligned RM82 sample oriented at nematic phase. One beam with different polarization(p-polarized 、 s-polarized) illuminated pre-aligned sample to verify polarization having less effect on orientation.. Through controlling the director and polymerized area to obtain aligned cell which has potential for electro-optic device.
Databáze: Networked Digital Library of Theses & Dissertations
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