In Situ Electron Microscopy of Poly(ethylene glycol) Crystals Grown in Thin Ionic Liquids Films
In Situ Electron Microscopy of Poly(ethylene glycol) Crystals Grown in Thin Ionic Liquids Films
复制标题
在离子液体薄膜中生长的聚乙二醇晶体的原位电子显微镜
DOI：
10.1002/pol.20190120
复制
发表时间：
2020
影响因子：
3.4
通讯作者：
Hoagland, David A.
中科院分区：
文献类型：
--
作者：
Srivastava, Satyam;Ribbe, Alexander E.;Russell, Thomas P.;Hoagland, David A.
用电子显微镜观察了在室温离子液体(IL)1-乙基-3-甲基咪唑乙基硫酸酯薄膜中生长的聚乙二醇晶体，作为开发非挥发性液体用于溶剂化/溶解聚合物材料纳米成像的第一步。晶体是通过冷却支撑的(在不同极性的表面上)和独立的溶液薄膜到室温而产生的。这种“开放的”，也就是说，没有液体细胞，在IL存在的情况下，对未染色的生长晶体进行显微镜检查。观察到了各种近二维的晶体形态，包括棒状、纤维、球晶、致密的刻面单晶和相互连接的网络，其特征尺寸从几十纳米到几十微米不等。棒材和纤维的电子衍射图显示出单晶状的长程有序结构。IL载体的性质对膜的形貌影响不大，但膜厚和冷却速度是重要的。为了评估溶剂极性的作用，还从1-乙基-3-甲基咪唑乙基硫酸盐和第二种IL，即极性较低的乙基-三丁基膦二乙基磷酸盐中生长了晶体；在这里，尽管形貌与纯IL相似，但纤维形态更常见。©2020威利期刊公司J.Polym。科学2020、58、478-486
Crystals of poly(ethylene glycol) grown in thin films of the room temperature ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium ethyl sulfate were examined by electron microscopy as a first step toward exploiting nonvolatile liquids for nanoscale imaging of solvated/dissolved polymeric materials. The crystals were generated by cooling supported (over surfaces of varied polarity) and freestanding solution films to room temperature. This “open,” that is, without liquid cell, microscopy was performed on unstained, as‐grown crystals in the presence of the IL. A variety of nearly two‐dimensional crystal morphologies were observed, including rods, fibers, spherulites, compact faceted single crystals, and interconnected networks, with characteristic sizes ranging from tens of nanometers to tens of microns. Electron diffraction patterns for the rods and fibers revealed single crystal‐like long‐range order. The nature of the IL support little affected the morphology, but film thickness and cooling rate proved important. To assess the role of solvent polarity, crystals were also grown from 1‐ethyl‐3‐methylimidazolium ethyl sulfate mixed with the second IL, the less polar ethyl‐tributyl‐phosphonium diethyl phosphate; here, although the morphologies were similar to those made with pure IL, fibrillar morphologies were more prevalent. © 2020 Wiley Periodicals, Inc. J. Polym. Sci.2020,58, 478–486