Characterization of a plant leaf cuticle model wax, phase behaviour of model wax-water systems

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• 作者：Anton Fagerstr枚m ; Vitaly Kocherbitov ; Peter Westbye ; Karin Bergstr枚m ; Varvara Mamontova ; Johan Engblom
• 关键词：Model wax ; Cuticle ; Phase diagram ; Hydration ; Eutectic melting ; Clivia Miniata Regel leaf
• 刊名：Thermochimica Acta
• 出版年：10 November, 2013
• 年：2013
• 卷：571
• 期：Complete
• 页码：42-52
• 全文大小：2325 K

文摘

We investigated the thermotropic phase behaviour of plant leaf intracuticular wax and two representatives of its main components, 1-docosanol (C₂₂H₄₅OH) and dotriacontane (C₃₂H₆₆), in dry and hydrated state. One objective was to obtain a model wax, which can be used to estimate formulations effects on cuticle diffusivity in vitro. The two wax components were chosen based on results from Gas Chromatography coupled to Mass Spectrometry analysis of cuticular wax. The wax was extracted from Clivia Miniata Regel leaves and contained 68% primary alcohols (C₁₆-C₃₂) and 16% n-alkanes (C₂₁-C₃₃). Differential Scanning Calorimetry, Polarized Light Microscopy and Small- and Wide Angle X-ray Diffraction were used to characterize the cuticular extract and the phase behaviour of the C₂₂H₄₅OH/C₃₂H₆₆/H₂O model system. Four individual crystalline phases were discovered in the model wax-water system and eutectic melting occurred in both dry and hydrated state. The thermotropic transitions of the model wax occur within the broader transition region of the extracted leaf wax.