Three-dimensional textures and defects of soft material layering revealed by thermal sublimation

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 110; no. 48; pp. 19263 - 19267
• Main Authors: Ki Yoon, Dong, Kim, Yun Ho, Kim, Dae Seok, Dae Oha, Seong, Smalyukh, Ivan I., Clark, Noel A., Jung, Hee-Tae
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 26.11.2013; NATIONAL ACADEMY OF SCIENCES; National Acad Sciences
• Subjects: Conic sections; Cooling; Cylinders; Edge dislocations; Emotional sublimation; Fluorescence; Imaging, Three-Dimensional - methods; Interfacial tension; Liquid crystal polymers; Liquid crystals; Liquid Crystals - chemistry; Material films; Materials Testing - methods; Microscopy, Atomic Force; Microscopy, Electron; Microscopy, Fluorescence; Molecules; Nanostructures - ultrastructure; Physical Sciences; Room temperature; Surface Properties; Surface texture; Thermogravimetry; Transmission electron microscopy; Visualization; X-Ray Diffraction; direct visualization; sublime
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1317922110

Layering is found and exploited in a variety of soft material systems, ranging from complex macromolecular self-assemblies to block copolymer and small-molecule liquid crystals. Because the control of layer structure is required for applications and characterization, and because defects reveal key features of the symmetries of layered phases, a variety of techniques have been developed for the study of soft-layer structure and defects, including X-ray diffraction and visualization using optical transmission and fluorescence confocal polarizing microscopy, atomic force microscopy, and SEM and transmission electron microscopy, including freeze-fracture transmission electron microscopy. Here, it is shown that thermal sublimation can be usefully combined with such techniques to enable visualization of the 3D structure of soft materials. Sequential sublimation removes material in a stepwise fashion, leaving a remnant layer structure largely unchanged and viewable using SEM, as demonstrated here using a lamellar smectic liquid crystal.