Taras Shevchenko National University of Kyiv, 60, Volodymyrska Str., 01033, Kyiv, Ukraine.
Phys Chem Chem Phys. 2019 Nov 13;21(44):24674-24683. doi: 10.1039/c9cp03761f.
Nanocrystallite-liquid phase transitions are studied for 1-octadecene confined in the pores of chemically functionalized silica gels. These silica gels possess similar fractal geometries of the pore system but differ in chemical termination of the surface, specific surface area (F) and pore volume (V). Linear dependencies of the melting temperature and specific melting heat on the F/V ratio are found for a series of silica gels with identical surface termination. A thermodynamic model based on experimental data is established, which explains the observed shift of the phase transition parameters for porous matrices with different surface chemistries. In addition, this model allows evaluation of actual changes in nanocrystallite density, surface tension and entropy upon melting.
研究了 1-十八烯在化学功能化硅胶孔中的纳米晶-液相转变。这些硅胶具有相似的孔系统分形几何形状，但表面化学终止、比表面积（F）和孔体积（V）不同。对于具有相同表面终止的一系列硅胶，发现熔融温度和比熔化热与 F/V 比呈线性关系。基于实验数据建立了热力学模型，该模型解释了观察到的具有不同表面化学性质的多孔基质相变参数的偏移。此外，该模型还可以评估纳米晶密度、表面张力和熵在熔融时的实际变化。
