Lyotropic and Thermotropic Phase Transitions in Films of Ionene-Alkyl Sulfate Complexes
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- 作者：Quanwei Yu ; Jens Frö ; mmel ; Thomas Wolff ; Miroslav Stepanek ; and Karel Prochá ; zka
- 刊名：Langmuir
- 出版年：2005
- 出版时间：July 19, 2005
- 年：2005
- 卷：21
- 期：15
- 页码：6797 - 6804
- 全文大小：260K
- 年卷期：v.21,no.15(July 19, 2005)
- ISSN：1520-5827
文摘
Five [X,Y]-ionenes [(CH2)XN+(CH3)2(CH2)YN+(CH3)2]nBr-2n were prepared (X = 3, 5; Y = 10, 12, 22).Using new preparation methods, dry, salt-free complexes with three n-alkyl sulfates (octyl, decyl, anddodecyl) were obtained. The ionenes and their complexes were characterized in methanol solution by lightscattering, viscometry, and fluorescent probe studies. The solid materials were investigated by means ofDSC, TG, and ATR-IR. Transparent films were formed from stoichiometric [3,10], [3,12], and[5,10]-ionene complexes with decyl and dodecyl sulfate. In the films, mesogenic phase transitions couldbe induced: dry films were optically isotropic; when exposed to elevated humidity, the films slowly becameoptically anisotropic because of a lyotropic transition to a hexagonal mesogenic phase. The relative humidity,at which the hexagonal phase developed, was distinct for each complex. The anisotropic phases wereconverted to isotropic in a thermotropic transition under controlled relative humidity at specific clearingtemperatures, which were higher for dodecyl complexes than for decyl complexes. This thermotropicisotropic-anisotropic transition could be cycled several times, but partial hydrolysis of the alkyl sulfatesreduced the reproducibility of transition points.