中文摘要：

采用分子动力学方法，分别研究了填充量为9个、18个和36个烷烃分子的纳米胶囊复合体系的微观结构和扩散性质。研究表明：三种纳米胶囊复合体系的微观结构发生了一定的变化，分别形成了连续的半周面、连续的单层圆周面和双层圆周面。三种纳米胶囊复合体系在温度升高过程中有序度逐渐降低，在固态时，填充了36个烷烃分子的体系中烷烃分子的有序度低于填充了9个和18个烷烃分子的体系，在液态时，填充了9个烷烃分子的体系，由于其相对自由空间较多和束缚较少，在相变后分子扭曲程度相对较高，有序度也低于填充了18个和36个烷烃分子的体系。三种纳米胶囊复合体系的相变温度分别为325K、325．3K和325．8K，受填充量的影响很小。随着填充量的增加其自扩散系数逐渐减小，这是由于有限的CNTs管内空间限制导致的，而且填充了36个烷烃分子的体系，因为在CNTs管内分为两层，其受到的束缚更大，使得自扩散系数比填充了9个和18个烷烃分子的体系降低了很多。

英文摘要：

The effect of alkane filling degree on the microstrueture and diffusion of nanocapsules were investigated using molecular dynamics （MD） methods. The filling degrees of n-hexacosane are 9 molecules, 18 molecules and 36 molecules, respectively. The MD simulation results indicated that three kinds of nanocapsules exhibited an orderly structural distribution near the inner wall of the CNTs, and formed a continuous semi-circular surface, continuous single-layer circular surface and double-layer circular surface, respectively. Three kinds of nanocapsules gradually turned disorderly with increasing temperature. The ordered degree of nanocapsules filled with 36 alkanes was lower than that of the system filled with 9 alkanes and 18 alkanes in solid state; while the ordered degree of nanocapsules filled with 9 alkanes was lower than that of the system filled with 18 alkanes and 36 alkanes in liquid state. The phase change temperatures of three kinds of nanocapsules are 325 K, 325.3 K and 325.8 K, respectively. The self-diffusion coefficients of three kinds of nanocapsules decrease with the increase of filling degree. The extreme confinement of CNT is the main factor for the decrease of the self-diffusion coefficient.