流体在聚偏氟乙烯纳米通道内的分子动力学模拟研究

发布时间：2018-03-18 08:16

本文选题：聚偏氟乙烯(PVDF)　切入点：纳米通道　出处：《天津工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：聚偏氟乙烯(PVDF),具有良好的化学稳定性、耐热性、机械稳定性,是一种性能优良的新型聚合物膜材料。对PVDF进行亲水化改性,提高材料的抗污染能力是膜科学领域的热点问题。然而,从理论上解释膜材料表面微观结构同膜亲水性、抗污染能力间的关联机制,仍有待研究。随着科技的发展与计算机应用领域的扩大,将传统实验应用于计算机中模拟已成为趋势,既能减少不必要的资源浪费,又能否定一部分不合理的实验猜想,在模拟过程中达到预期目的。本文采用分子动力学模拟方法,建立PVDF模型,并针对其性能,对流体在纳米级别的PVDF膜通道内的运动过程进行了计算研究。采用纳米通道模型,模拟流体在PVDF纳米通道内的运动,有利于研究流体流动的表面效应,研究流体在纳米通道内的表面亲润性、非对称通道内的运动规律、流体的运动特性以及膜表面性质改变对流体的影响。本文利用Material Studio 6.0软件Dmol3模块建立PVDF晶体模型并对其几何结构进行优化处理。随后结合文献建立力场参数,升高温度对PVDF膜进行烧结处理,再通过逐步降温得到熔融态的膜通道体系。通过LAMMPS软件进行分子动力学模拟,结果表明:熔融态的PVDF膜表面流体分子分布更均匀,并且亲水性得到改善;甲醇溶液与水溶液对膜表面性质的影响不明显;不同孔径的PVDF纳米通道对溶液分子在孔道的分布有一定的影响,孔径增大,孔径对流体的抑制作用就会降低,溶液分子分布越易趋于均匀。
[Abstract]:Polyvinylidene fluoride (PVDF) has good chemical stability, heat resistance and mechanical stability. It is a new type of polymer membrane material with excellent properties. It is a hot issue in the field of membrane science to improve the anti-fouling ability of materials. However, the correlation mechanism between the surface microstructure of membrane materials and membrane hydrophilicity and anti-fouling ability is theoretically explained. With the development of science and technology and the expansion of computer application field, it has become a trend to apply traditional experiments to computer simulation, which can not only reduce unnecessary waste of resources, but also negate some unreasonable experimental conjectures. In this paper, the PVDF model is established by using molecular dynamics simulation method, and the motion process of fluid in PVDF film channel at nanometer level is calculated and studied according to its performance. Simulating the movement of fluid in PVDF nanochannel is beneficial to study the surface effect of fluid flow, the surface hydrophilicity of fluid in the nanochannel, and the motion law in asymmetric channel. In this paper, Material Studio 6.0 Dmol3 module is used to establish the PVDF crystal model and optimize its geometric structure. Then, the force field parameters are established in combination with the literature. The PVDF membrane was sintered by increasing the temperature, and then the melt channel system was obtained by decreasing the temperature step by step. The molecular dynamics simulation was carried out by LAMMPS software. The results showed that the fluid molecules on the surface of the PVDF film in the molten state distributed more evenly. The hydrophilicity was improved, the effect of methanol solution and aqueous solution on the surface properties of the membrane was not obvious, and the distribution of solution molecules in the channel was influenced by different pore sizes of PVDF nanochannels, and the pore size was increased. The inhibition of pore size on the fluid will be reduced, and the distribution of solution molecules tends to be uniform.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

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