Bašnec Kristina, Perše Lidija Slemenik, Šumiga Boštjan, Huskić Miroslav, Meden Anton, Hladnik Aleš, Podgornik Bojana Boh, Gunde Marta Klanjšek
Radeče Papir Nova, d.o.o., Njivice 7, SI-1433, Radeče, Slovenia.
National Institute of Chemistry, Hajdrihova 19, SI-1000, Ljubljana, Slovenia.
Sci Rep. 2018 Apr 3;8(1):5511. doi: 10.1038/s41598-018-23789-2.
Reversible colour change of leuco dye-based composites is in general closely related to their phase change, thus the two phenomena should occur at around the same temperature and should be influenced similarly. However, spatial confinement of the analysed sample affects the change in colour differently compared to its phase transition and the most pronounced effects can be observed during cooling. The bulk composite is coloured while still liquid and the colour hysteresis does not exhibit a loop. In an open-porous medium the colouration coincides well with the crystallization and the colour hysteresis widens to about 4 °C. Microencapsulated composite exhibits two crystallization processes, one of them taking place at the bulk crystallization temperature and the other one at about 20 °C lower. Under such conditions the composite is coloured just before the onset of the second crystallization, i.e. about 15 °C below crystallization in the bulk, and the corresponding colour hysteresis widens to 18 °C. The two crystallization forms are thermally independent and have the same crystalline structure. These effects should be taken into account when designing future applications where the phase-changing materials are implemented.
基于无色染料的复合材料的可逆颜色变化通常与其相变密切相关，因此这两种现象应在大致相同的温度下发生，并且受到的影响也应相似。然而，与相变相比，被分析样品的空间限制对颜色变化的影响不同，并且在冷却过程中可以观察到最明显的影响。块状复合材料在仍为液态时就有颜色，并且颜色滞后不呈现环状。在开孔介质中，显色与结晶恰好吻合，并且颜色滞后扩大到约4℃。微胶囊化复合材料表现出两个结晶过程，其中一个在块状结晶温度下发生，另一个在低约20℃的温度下发生。在这种条件下，复合材料恰好在第二次结晶开始之前显色，即在块状结晶温度以下约15℃时显色，并且相应的颜色滞后扩大到18℃。这两种结晶形式在热学上是独立的，并且具有相同的晶体结构。在设计未来应用中实施相变材料时，应考虑这些影响。
