측쇄형 액정폴리아세틸렌 유도체의 열안정성 및 액정 성질에 관한 연구

오세용; Akagi K; Shirakawa H

HWAHAK KONGHAK, Vol.34, No.2, 154-158, April, 1996

Studies on the Thermal Stability and Liquid Crystalline Properties of Side-Chain Liquid Crystalline Polyacetylene Derivatives

오세용, Akagi K, Shirakawa H

초록

Ziegler-Natta와 metathesis 촉매를 사용하여 측쇄에 mesogenic moiety로서 cyclohexylphenyl 또는 biphenyl기를 갖는 액정폴리아세틸렌 유도체를 합성하였다. 특히 metathesis 촉매(MoCl₅-Ph₄Sn)로 합성한 고분자는 trans형의 배위를 가지며, Ziegler-Natta 촉매계의 고분자보다 열안전성이 우수하였다. 시차주사열량계와 편광현미경의 측정으로 모든 고분자의 액정 성질을 조사하였다. Alkylcyclohexylphenyl 또는 pentylbiphenyl기를 함유한 고분자는 fan-shaped 구조를 가지는 smectic A 액정상을 나타내었다. 또한 상전이에 따른 엔탈피 변화, cis형에서 trans 구조로의 열 이성화 및 분자량에 관해서 이들 고분자의 분광학적 특성을 분석하였다.

We have synthesized liquid crystalline polyacetylene derivatives with a cyclohexyl phenyl or biphenyl group as a mesogenic moiety in the side group by using Ziegler-Natta and metathesis catalysts. Especially, polymers prepared by the metathesis catalyst(MoCl₅-Ph₄Sn) had trans-rich configuration, and their thermal stability was more excellent than polymers prepared by the Ziegler-Natta catalyst. Liquid crystalline properties of all polymers were investigated through measurements of differential scanning calorimetry(DSC) and polarizing microscopy. The polymers consisting of alkyl cyclohexylphenyl or pentylbiphenyl group are found to show a smectic A liquid crystalline phase with a fan-shaped texture. Spectroscopic characteristics of these polymers were also analyzed with respect to molecular weights, thermal isomerization of the cis to trans form and enthalpy changes associated with phase transitions.

Keywords:Polyacetylene Derivatives;Trans-Rich Configuration;Thermal Stability;Isomerization;Liquid Crystalline

[References]

Ciferri A, Krigbaum WR, Meyer RB, "Polymer Liquid Crystals," Academic Press, New York (1982)
Coles HJ, Simon R, Polymer, 26, 1801 (1985)
Kim HR, Macromolecules, 22, 2596 (1989)
Ballauff M, Angew. Chem.-Int. Edit., 28, 253 (1989)
Moigne JL, Hilberer A, Makromol. Chem., 192, 515 (1992)
Oh SY, Ezaki R, Akagi K, Shirakawa H, J. Polym. Sci. A: Polym. Chem., 31, 2977 (1993)
Oh SY, Akagi K, Shirakawa H, Synth. Met., 32, 245 (1989)
Oh SY, Akagi K, Shirakawa H, HWAHAK KONGHAK, presentation
Oh SY, Oguri F, Akagi K, Shirakawa H, J. Polym. Sci. A: Polym. Chem., 31, 781 (1993)
Sondheimer F, Ben-Efraim DA, Wolovsky R, J. Am. Chem. Soc., 83, 1675 (1961)
Oh SY, Akagi K, Shirakawa H, Araya K, Macromolecules, 26, 6203 (1993)

[Referenced By]

[1] Ciferri A, Krigbaum WR, Meyer RB, "Polymer Liquid Crystals," Academic Press, New York (1982)

[2] Coles HJ, Simon R, Polymer, 26, 1801 (1985)

[3] Kim HR, Macromolecules, 22, 2596 (1989)

[4] Ballauff M, Angew. Chem.-Int. Edit., 28, 253 (1989)

[5] Moigne JL, Hilberer A, Makromol. Chem., 192, 515 (1992)

[6] Oh SY, Ezaki R, Akagi K, Shirakawa H, J. Polym. Sci. A: Polym. Chem., 31, 2977 (1993)

[7] Oh SY, Akagi K, Shirakawa H, Synth. Met., 32, 245 (1989)

[8] Oh SY, Akagi K, Shirakawa H, HWAHAK KONGHAK, presentation

[9] Oh SY, Oguri F, Akagi K, Shirakawa H, J. Polym. Sci. A: Polym. Chem., 31, 781 (1993)

[10] Sondheimer F, Ben-Efraim DA, Wolovsky R, J. Am. Chem. Soc., 83, 1675 (1961)

[11] Oh SY, Akagi K, Shirakawa H, Araya K, Macromolecules, 26, 6203 (1993)