Using molecular dynamics to simulate realistic structures of nitrocellulose of different nitration levels
Using molecular dynamics to simulate realistic structures of nitrocellulose of different nitration levels
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DOI：
10.1039/d2cp05550c
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发表时间：
2022-12-26
影响因子：
3.3
通讯作者：
Skylaris, Chris-Kriton
中科院分区：
文献类型：
--
作者：
Gibbon, Catriona;Di Pietro, Poppy;Skylaris, Chris-Kriton
硝化棉是纤维素的活性衍生物，纤维素是最常见的天然材料之一。纤维素的硝化降低了结构的稳定性，这意味着对其结构和反应的了解较少。虽然纤维素通常以完全结晶的形式存在，但硝化纤维素更常见的是准晶态或无定形。我们提出了一种基于分子动力学模拟的协议，用于创建真实的硝化棉结构，特别是关注正在创建的系统的结晶度。我们还将提供用于量化这里创建的结构的结晶度的几何和动力学参数的详细分析，其中硝化水平从0-14.14wt%的氮含量变化。准晶纤维素不是用这里设计的方案制造的，尽管人们发现硝基纤维素体系硝化程度越高，结构就越倾向于准晶。这是由于存在的氢键数量减少，以及推动链分离的官能团的大小增加，削弱了结构链之间的相互作用。所创建的结构代表了现实系统，在未来将能够用来进一步了解硝化棉的长期储存。
Nitrocellulose is a reactive derivative of cellulose, one of the most commonly occurring natural materials. Nitration of cellulose decreases the stability of the structure, meaning less is understood about its structure and reactions. Although cellulose is often found in fully crystalline forms, nitrocellulose is more commonly paracrystalline, or amorphous. We present a protocol based on molecular dynamics simulations for creating realistic structures of nitrocellulose, particularly focusing on the crystallinity of the systems being created. We will also provide a detailed analysis of the geometric and dynamical parameters used to quantify the degree of crystallinity for the structures created here, with nitration levels varying from 0-14.14 wt% nitrogen content. Paracrystalline cellulose was not created using the protocol designed here, although it was found that the more nitrated a nitrocellulose system, the more the structure tends to paracrystallinity. This is due to a decrease in the number of hydrogen bonds present, and an increase in the size of the functional groups pushing the chains apart and weakening the interactions between the chains of the structure. The structures created are representative of realistic systems, which in the future will be able to be used to build further understanding of long-term storage of nitrocellulose.