基于分子动力学模拟的改性部分水解聚丙烯酰胺耐温机理

Temperature resistance mechanism of modified partially hydrolyzed polyacrylamide based on molecular dynamics simulation

关键词:  分子模拟  耐温  氢键  回转半径  扩散系数  径向分布函数 

Key words:  molecular simulation  temperature resistance  hydrogen bond  gyration radius  diffusion coefficient  radial distribution function

摘要:

目的 为了探明不同功能单体如何影响部分水解聚丙烯酰胺的耐温性能。方法 设计了3种不同类型的功能单体改性部分水解聚丙烯酰胺,采用分子动力学研究其在高温下的分子链舒展程度、体系小分子扩散状态以及与水形成的氢键强度。结果 阴离子单体AMPS因其含有磺酸基团,与水分子形成的氢键更强,抑制聚合物链在高温下的“去水化”,使聚合物的耐温性能提升；非离子单体NVP具有环状刚性结构,提升聚合物链的抗卷曲能力,避免了聚合物链的过度卷曲,可增强聚合物的耐温性能；阳离子单体DADMAC在水中易与羧酸基团相互吸引,使得聚合物分子链易于卷曲,降低了聚合物的耐温性能。结论 能与水形成更强氢键强度的基团以及具有抗卷曲能力的环状结构的单体,更利于提升部分水解聚丙烯酰胺的耐温性能。 

Abstract:

Objective This study is aiming to explore how the different functional monomers affect the temperature resistance performance of partially hydrolyzed polyacrylamide. Methods Three kinds of partially hydrolyzed polyacrylamide modified by different functional monomers were designed. The stretching degree of polymer molecular chains, the diffusion state of small molecules and the strength of hydrogen bonds between polymer with water were investigated at high temperature by molecular dynamics simulation. Results The anionic monomer AMPS restrained polymer chain“dehydration”and improved its temperature resistance performance, on account of AMPS having a sulfoacid group, and it can promote the formation of stronger hydrogen bonds between polymer chain and water. Since the nonionic monomer NVP has a rigidly ring-shaped structure, it can improve polymer chain curl resistance property and avert its excessive curl, and enhance the temperature resistance performance of the polymer. In addition, the cationic monomer DADMAC is easy to attract the carboxylate group, which causes the polymer chain to curl more easily and reduces its temperature resistance. Conclusion sThe groups that can both form stronger hydrogen bond strength with water and the ring-shaped monomers with curl resistance ability are more conducive to improving temperature resistance of partially hydrolyzed polyacrylamide.