Maghami Mahboobeh, Abdelrasoul Amira
Department of Chemical and Biological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan, S7N 5A9, Canada.
Department of Chemical and Biological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan, S7N 5A9, Canada.
J Mol Graph Model. 2020 Nov;100:107656. doi: 10.1016/j.jmgm.2020.107656. Epub 2020 Jul 8.
The goal of this study is to design a novel zwitterionic (ZW)-poly (vinylidene fluoride) (PVDF) membrane with high hydrophilicity potential using the pair interaction energy decomposition analysis (PIEDA) integrated with fragment molecular orbital (FMO) method. In addition, the differential hydration and efficiency of salt rejection of the novel zwitterion and original PVDF were investigated using molecular dynamics simulation (MDS). Within this study computational methods were applied to investigate the performance of zwitterionic moieties derived from three different anionic groups in the ZW head, specifically, carboxylate, sulfonate, and phosphate. This approach was used in addition to the inclusion of a linker between the ZW head and the PVDF backbone, such as trimethyl ammonium groups and hydroxyl group for an increase in PVDF membrane hydrophilicity. The quantum chemical calculations were employed to examine the hydration structure of moieties, the number of hydrogen bonding instances, and hydration free energy. The interactions between the ZW moieties on PVDF membranes with water molecules confirmed that they depended on the charged groups and the chemical groups between charged groups. The results pointed to differences in hydrophilicity, membrane water uptake due to their structural properties depending on the types of anionic groups involved, polar groups between charged groups, and the hydrophilic groups as a linker between charged groups of the zwitterions to the PVDF polymer backbone. The double zwitterionic PMAL®-C-CB-OH-SB-PVDF was formed through protonated carboxyl group on backbone of copolymer PMAL®-C, and protonated nitrogen atom of amide group. This double zwitterion showed strong electrostatic interactions between individual water and secondary ammonium and Oxygen of carboxybetaine, compared to PMAL®-C-OH-SB-PVDF model. The simulated results using MDS confirmed the hydrophilicity of PMAL®-C-CB-OH-SB-PVDF and showed that the positive and negative centers of zwitterionic polymer chains on PVDF membrane surface can interact with the ions, contributing into the increase of charge density. Our designed hydrophilic zwitterion PVDF membrane, and especially the double zwitterion membrane, is an exciting development that can be used in a broad range of water applications.
本研究的目标是使用与片段分子轨道（FMO）方法相结合的对相互作用能分解分析（PIEDA），设计一种具有高亲水性潜力的新型两性离子（ZW）-聚偏氟乙烯（PVDF）膜。此外，使用分子动力学模拟（MDS）研究了新型两性离子和原始PVDF的差异水合作用及盐截留效率。在本研究中，应用计算方法研究了ZW头部中源自三种不同阴离子基团（具体为羧酸盐、磺酸盐和磷酸盐）的两性离子部分的性能。除了在ZW头部和PVDF主链之间引入连接基团（如三甲铵基团和羟基）以增加PVDF膜的亲水性外，还采用了这种方法。采用量子化学计算来研究部分的水合结构、氢键实例数量和水合自由能。PVDF膜上的ZW部分与水分子之间的相互作用证实，它们取决于带电基团以及带电基团之间的化学基团。结果表明，由于其结构性质，亲水性、膜吸水率存在差异，这取决于所涉及的阴离子基团类型、带电基团之间的极性基团以及作为两性离子带电基团与PVDF聚合物主链之间连接基团的亲水基团。双两性离子PMAL®-C-CB-OH-SB-PVDF是通过共聚物PMAL®-C主链上的质子化羧基和酰胺基团的质子化氮原子形成的。与PMAL®-C-OH-SB-PVDF模型相比，这种双两性离子在单个水与仲铵以及羧基甜菜碱的氧之间表现出强烈的静电相互作用。使用MDS的模拟结果证实了PMAL®-C-CB-OH-SB-PVDF的亲水性，并表明PVDF膜表面两性离子聚合物链的正负极中心可以与离子相互作用，有助于增加电荷密度。我们设计的亲水性两性离子PVDF膜，尤其是双两性离子膜，是一项令人兴奋的进展，可用于广泛的水应用领域。
