Temperature Effects on LC Droplets formation of PDLC Films with Thermoplastic Matrix

Wonsool Ahn; KiRyong Ha

Korea Polymer Journal, Vol.7, No.2, 130-135, April, 1999

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Temperature Effects on LC Droplets formation of PDLC Films with Thermoplastic Matrix

Wonsool Ahn^†, and KiRyong Ha

Department of Chemical Engineering, Keimyung University, Taegu 704-701, Korea

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A mixture of PMMA/MMA/LC was used to investigate the formation of liquid crystal(LC) droplets induced by polymerization and electro-optic properties of polymer-dispersed liquid crystal (PDLC) film. Experiments showed that, on the contrary to the cross-linkable epoxy/hardener/LC system, average size of LC droplets of PMMA/MMA/LC system increased linearly as reaction temperature increased. This fact was considered as the combined effect of t재 main factors: the effect of lowering the viscosity and that of decreased degree of polymerization with increased temperature, leading to easier coalescence of LC droplets after phase separation, Electro-optic measurements of the resulting PDLC film indicated that the macroscopic electro-optic response could be closely related to the microscopic LC droplet sizes, showing that threshold voltage of the film was approximately proportional to the inverse of LC droplets size.

[References]

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Doane JW, Viz AN, Au BG, Bummer S, Appl. Phys. Lett., 48, 286 (1986)
Ahn W, Kim YC, Kim H, Kim SC, Macromolecules, 25, 5002 (1992)
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Fuh A, Caporaletti O, J. Appl. Phys., 66, 5278 (1989)
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[Related Articles]

[1] Fergason JL, SID (Society for Information Display) Int. Sump. Dig. Tech. Papers, 16, 68 (1985)

[2] Doane JW, Viz AN, Au BG, Bummer S, Appl. Phys. Lett., 48, 286 (1986)

[3] Ahn W, Kim YC, Kim H, Kim SC, Macromolecules, 25, 5002 (1992)

[4] Ahn W, Kim DY, Kim YC, Kim CY, Ferroelectrics, 156, 191 (1994)

[5] West JL, Mol. Cryst. Liq. Cryst., 157, 427 (1988)

[6] Doane JW, Golemme A, West JL, Whitehead JB, Wu BG, Mol. Cryst. Liq. Cryst., 165, 511 (1988)

[7] Park LS, Ahn WS, Kum CD, Polym.(Korea), 21(1), 26 (1997)

[8] Grand C, Achard MF, Hardouin F, Liq. Cryst., 22, 287 (1997)

[9] Noh CH, Jung JE, Kim JY, Sakong DS, Choi KS, Mol. Cryst. Liq. Cryst., 237, 299 (1993)

[10] Smith GW, Vaz NA, Liq. Cryst., 3, 543 (1988)

[11] Vaz NA, Montgomery GP, J. Appl. Phys., 62, 3161 (1987)

[12] Wu BG, West JL, Doane JW, J. Appl. Phys., 62, 3925 (1987)

[13] Vaz NA, Montgomery GP, J. Appl. Phys., 65, 5043 (1989)

[14] Fuh A, Caporaletti O, J. Appl. Phys., 66, 5278 (1989)

[15] Bird RB, Stewart WE, Lightfoot EN, Transport Phenomena, 2nd Ed., John Wiley & Sons, N.Y., Ch. 2, pp. 60 (1960)

[16] Odian G, Principles of Polymerization, 3rd Ed., John Wiley & Sons, N.Y., Ch. 3 (1981)

[17] Drzaic PS, J. Appl. Phys., 60, 2142 (1986)