High pressure differential thermal analysis (DTA) of the phase behaviours of didodecyl-dimethylammoniumbromide (DDAB) and ditetradecyldimethylammoniumbromide (DTAB)

被引：2

作者：

Hamann, F ^{[1
]}

Reuter, J ^{[1
]}

Wurflinger, A ^{[1
]}

Godlewska, M ^{[1
]}

Dynarowicz, P ^{[1
]}

机构：

[1] Ruhr Univ Bochum, Inst Chem Phys, D-44780 Bochum, Germany

来源：

LIQUID CRYSTALS: CHEMISTRY AND STRUCTURE | 1998年 / 3319卷

关键词：

dialkyldimethylammonium bromides; high pressure; DTA; phase transitions; thermodynamics;

D O I：

10.1117/12.301277

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Dialkyldimethylammonium halides are known br their applications as commercial detergents and for their membrane-mimetic properties. They display both thermotropic and lyotropic liquid crystalline properties. In this work we establish the T(p)-phase diagrams (up to 300 MPa) of two representatives, namely diodecyl- (DDAB) and ditetradecyl- (DTAB) ammonium bromides. The transitions between crystal, smectic II and smectic I phases were recorded using a high-pressure differential thermal analysis device. For both compounds the stable range of smectic II phase is pressure-limited, resulting in a triple point crystal/ smectic II/ smectic I. Enthalpy changes at ambient pressure have been determined with the aid of a commercial heat flux differential scanning calorimeter. Volume changes were calculated from the slopes of the transitions lines, employing the Clausius Clapeyron equation.

引用

页码：166 / 169

页数：4