College of Science, Nanjing Forestry University, Nanjing 210037, China.
State Key Laboratory of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China.
J Phys Chem B. 2021 May 27;125(20):5420-5433. doi: 10.1021/acs.jpcb.1c01969. Epub 2021 May 12.
The quantitative relationship between the surface chemistry of carbon materials and the compatibility with polymers is a fundamental and vital physical chemistry problem in the field of polymer nanocomposites. Traditional experimental methods are difficult to solve this problem, so no theory has been formed to guide the functionalization of carbon materials. In this work, the quantitative relationship between functional groups and Hildebrand (δ) and transformed Hansen (δ and δ) solubility parameters of fullerene (C60) was determined by molecular dynamics simulation. Besides, which solubility parameter can more accurately predict the compatibility between C60 and three typical polymers with different polarity as a function of grafting ratio is investigated. Very interestingly, no matter which group is grafted, δ and δ of C60 show a slight increase first and then a decrease with the grafting ratio, whereas δ first increases abruptly and then decreases slightly. The introduction of polar groups (-OH, -COOH, and -NH) is conducive to improving the compatibility between C60 and polymers, whereas the introduction of the nonpolar group (-CH) is not. In terms of predicting compatibility, the Hildebrand solubility parameter is better than the Hansen solubility parameter due to the nonpolar nature of the polymers, even for nitrile butadiene rubber. Finally, the optimum grafting ratios corresponding to the maximum binding energies of C60/polymers mixtures were obtained. This study provides a new understanding of the functionalization of C60 at the molecular level and promotes the development of the theory of the thermodynamics of mixing.
碳材料的表面化学与其与聚合物的相容性之间的定量关系是聚合物纳米复合材料领域中一个基本且至关重要的物理化学问题。传统的实验方法很难解决这个问题，因此没有形成理论来指导碳材料的功能化。在这项工作中，通过分子动力学模拟确定了富勒烯（C60）的官能团与 Hildebrand（δ）和转化的 Hansen（δ 和 δ）溶解度参数之间的定量关系。此外，还研究了哪个溶解度参数可以更准确地预测 C60 与三种具有不同极性的典型聚合物作为接枝率函数的相容性。非常有趣的是，无论接枝哪种基团，C60 的δ 和 δ 均先随着接枝率的增加而略有增加，然后略有下降，而 δ 则先急剧增加，然后略有下降。引入极性基团（-OH、-COOH 和 -NH）有利于提高 C60 与聚合物的相容性，而引入非极性基团（-CH）则不然。在预测相容性方面，由于聚合物的非极性性质，Hildebrand 溶解度参数优于 Hansen 溶解度参数，即使对于丁腈橡胶也是如此。最后，得到了对应于 C60/聚合物混合物最大结合能的最佳接枝比。该研究为碳材料的分子水平功能化提供了新的认识，并促进了混合热力学理论的发展。
