Sensor and Actuator Systems (SAS), Department of Physics, Chemistry and Biology (IFM) , Linköping University , Linköping 581 83 , Sweden.
Laboratoire de Physicochimie des Polymères et des Interfaces, Institut des Matériaux , Université de Cergy-Pontoise , Cergy-Pontoise Cedex 95000 , France.
ACS Appl Mater Interfaces. 2018 Jun 27;10(25):21601-21611. doi: 10.1021/acsami.8b03537. Epub 2018 Jun 13.
An ionic conducting membrane is an essential part in various electrochemical devices including ionic actuators. To miniaturize these devices, micropatterns of ionic conducting membrane are desired. Here, we present a novel type of ionogel that can be patterned using standard photolithography and soft imprinting lithography. The ionogel is prepared in situ by UV-initiated free-radical polymerization of thiol acrylate precursors in the presence of ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The resultant ionogel is very flexible with a low Young's modulus (as low as 0.23 MPa) and shows a very high ionic conductivity (up to 2.4 × 10 S/cm with 75 wt % ionic liquid incorporated) and has a reactive surface due to the excess thiol groups. Micropatterns of ionogel are obtained by using the thiol acrylate ionogel solution as an ionic conducting photoresist with standard photolithography. Water, a solvent immiscible with ionic liquid, is used as the photoresist developer to avoid complete removal of ionic liquid from thin micropatterns of the ionogel. By taking advantage of the reactive surface of ionogels and the photopatternability, ionogels with complex three-dimensional microstructure are developed. The surface of the ionogels can also be easily patterned using UV-assisted soft imprinting lithography. This new type of ionogels may open up for building high-performance flexible electrochemical microdevices.
离子导电膜是各种电化学装置（包括离子致动器）的重要组成部分。为了使这些装置微型化，需要对离子导电膜进行微图案化处理。在这里，我们提出了一种新型的离子凝胶，它可以使用标准的光刻和软压印光刻进行图案化。离子凝胶是通过在离子液体 1-乙基-3-甲基咪唑双（三氟甲烷磺酰基）亚胺存在下，通过紫外光引发的巯基丙烯酸酯前体的自由基聚合原位制备的。所得的离子凝胶非常柔韧，杨氏模量低（低至 0.23 MPa），离子电导率非常高（高达 2.4×10 S/cm，含有 75wt%的离子液体），并且由于过量的巯基基团而具有反应性表面。通过使用巯基丙烯酸酯离子凝胶溶液作为具有标准光刻的离子导电光致抗蚀剂，可以获得离子凝胶的微图案。水，一种与离子液体不混溶的溶剂，被用作光致抗蚀剂显影剂，以避免从离子凝胶的薄微图案中完全去除离子液体。利用离子凝胶的反应性表面和光图案形成能力，可以开发具有复杂三维微结构的离子凝胶。离子凝胶的表面也可以很容易地使用紫外辅助软压印光刻进行图案化。这种新型离子凝胶可能为构建高性能柔性电化学微器件开辟了新的途径。
