Nagarjuna Ravikiran, Saifullah Mohammad S M, Ganesan Ramakrishnan
Department of Chemistry, Birla Institute of Technology and Science (BITS) Pilani, Hyderabad Campus Jawahar Nagar, Shameerpet Mandal Hyderabad 500078 India
Institute of Materials Research and Engineering, ASTAR (Agency for Science, Technology, and Research) 2 Fusionopolis Way, #08-03 Innovis Singapore 138634 Republic of Singapore.
RSC Adv. 2018 Mar 22;8(21):11403-11411. doi: 10.1039/c8ra01688g. eCollection 2018 Mar 21.
UV-nanoimprint lithography (UV-NIL) is a promising technique for direct fabrication of functional oxide nanostructures. Since it is mostly carried out in aerobic conditions, the free radical polymerization during imprinting is retarded due to the radical scavenging ability of oxygen. Therefore, it is highly desirable to have an oxygen-insensitive photo-curable resin that not only alleviates the requirement of inert conditions but also enables patterning without making substantial changes in the process. Here we demonstrate the formulation of metal-containing resins that employ oxygen-insensitive thiol-ene photo-click chemistry. Allyl acetoacetate (AAAc) has been used as a bifunctional monomer that, on one hand, chelates with the metal ion, and on the other hand, offers a reactive alkene group for polymerization. Pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), a four-arm thiol derivative, is used as a crosslinker as well as an active component in the thiol-ene photo-click chemistry. The FT-IR analyses on the metal-free and metal-containing resin formulations revealed that the optimum ratio of alkene to thiol is 1 : 0.5 for an efficient photo-click chemistry. The thiol-ene photo-click chemistry has been successfully demonstrated for direct imprinting of oxides by employing TiO and TaO as candidate systems. The imprinted films of metal-containing resins were subjected to calcination to obtain the corresponding patterned metal oxides. This technique can potentially be expanded to other oxide systems as well.
紫外纳米压印光刻技术（UV-NIL）是一种用于直接制造功能性氧化物纳米结构的很有前景的技术。由于该技术大多在有氧条件下进行，压印过程中的自由基聚合反应因氧气的自由基清除能力而受到抑制。因此，非常需要一种对氧气不敏感的光固化树脂，它不仅能减轻对惰性条件的要求，还能在不使工艺发生重大改变的情况下实现图案化。在此，我们展示了采用对氧气不敏感的硫醇-烯光点击化学的含金属树脂的配方。乙酰乙酸烯丙酯（AAAc）被用作双功能单体，一方面它与金属离子螯合，另一方面它提供用于聚合的反应性烯烃基团。季戊四醇四（3-巯基丙酸酯）（PETMP），一种四臂硫醇衍生物，用作交联剂以及硫醇-烯光点击化学中的活性成分。对不含金属和含金属的树脂配方进行的傅里叶变换红外光谱分析表明，对于高效的光点击化学，烯烃与硫醇的最佳比例为1∶0.5。通过将TiO和TaO作为候选体系，硫醇-烯光点击化学已成功用于氧化物的直接压印。对含金属树脂的压印膜进行煅烧以获得相应的图案化金属氧化物。该技术也有可能扩展到其他氧化物体系。
