官能数可控的聚合反应分子模拟方法

The molecular simulation method for functionality controllable polymerization

为了便于对复杂体系,诸如网络聚合物和大分子聚集体的形成过程以及微观结构进行系统研究,能够发生化学反应形成新的具有确定拓扑结构的分子模拟方法起着非常重要的作用。本工作在分子动力学方法中引入摩斯势,并且对粒子间非键排斥作用参数进行优化,成功实现了对反应基团之间饱和官能数的调控。对模型体系的分析表明,反应基团之间的键合符合动态交联过程,并且键合作用势对体系粒子分布没有明显影响。利用该方法设定最大官能数为2对小分子单体进行聚合反应的模拟,反应生成寡聚物的数均聚合度和反应程度符合线型缩聚反应的关系。在短链分子的末端加上这些反应性基团,并通过参数调控设定其最大官能数为4,通过分子动力学模拟即可以使短链分子相互键连形成复杂的聚合物随机网络结构,网络的形成过程仍然符合凝胶化的平均场理论。

The molecular simulation method, which makes new predefined topological structures through random reactions between molecules, is important to facilitate the investigation on complicated systems, such as the formation and their microscopic structures of network polymer and the aggregates of macromolecules. In the present work, the shifted Morse potential was introduced to normal mo- lecular dynamics simulations; the functionality of the reactive particles was successfully controlled through the parameterization of their non-bonded repulsion interactions. It was demonstrated in the model systems that bonding of the reactive particles abided well with the dynamic cross-linking process and the bonding potential has almost no interference to the population of particles in the systems. After setting the maximum functionality to 2, the methods was used for the linear polymerization of small molecules, and the number average degree of polymerization of the formed oligomers corresponds well with the reaction extent of linear condensation reactions. When such reactive particles were added to short linear chains and setting their maximum functionality to 4, the complicated random network po- lymer structure can be obtained through their end-linking reactions, and the formation of network polymer coincides well with the mean field gelation model.