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International Center for Materials Nanoarchitectonics (WPI-MANA)

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[[Research Highlights Vol.6] Inorganic materials display massive and instantaneous swelling and shrinkage](https://mdr.nims.go.jp/datasets/0f1bc6ad-83d8-4bea-b263-6a02f1fdc9e5)

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2022/04/04 10:27 Inorganic materials display massive and instantaneous swelling and shrinkage| MANAhttps://www.nims.go.jp/mana/research/highlights/vol6.html 1/3Previous  Index  NextResearch Highlights[Vol. 6]Inorganic materials display massive and instantaneous swelling and shrinkage29 Mar, 2013The first observation of massive swelling and shrinkage of inorganic layeredmaterials like a biological cell provides insights into the production of two-dimensional nanocrystals.Macroscopic volume and microscopy characterization of the samplesbefore and after swelling.The parent H0.8[Ti1.2Fe0.8]O4・H2O microcrystals exhibit platelets with lateralsizes of ~15 µm×35 µm and a thickness of 2-3 µm. The interlayer spacing is0.89 nm; thus, the platelets are composed of ~3000 regularly stacked layers.With addition of amine solutions, the samples “balloon” spontaneously, and themacroscopic volume of the swollen crystals changes with various DMAE solutions,which shows the maximum volume increase at DMAE/H+ = 0.5. Opticalmicroscopy characterizations reveal extended lamellar structures. The longestswollen length is ~200-250 µm in DMAE/H+ = 0.5. At high concentrations, theswelling is somewhat suppressed, with swollen length of ~100 µm atDMAE/H+ = 10.Two-dimensional (2D) nanocrystals have unique properties that may be useful for a range ofapplications. Consequently there is high interest in the mechanism for producing 2D nanocrystalsby exfoliating materials with layered structures. Now researchers in Japan have reported anunusual phenomenon that layered materials undergo dramatic swelling without breaking intohttps://www.nims.go.jp/mana/research/highlights/vol5.htmlhttps://www.nims.go.jp/mana/research/highlights/index.htmlhttps://www.nims.go.jp/mana/research/highlights/vol7.html2022/04/04 10:27 Inorganic materials display massive and instantaneous swelling and shrinkage| MANAhttps://www.nims.go.jp/mana/research/highlights/vol6.html 2/3separate 2D crystal layers. “The findings demonstrate important implications for and chemicalinsight into the exfoliating process,” say the researchers.Certain ions or solvents can infiltrate materials with layered structures. This ‘intercalation’sometimes causes excessive swelling and ultimately exfoliation into separate layers. The process ofexfoliation has been studied in a number of materials including graphite, metal oxides, andhydroxides among others. In all these materials, exfoliation into separate layers occurs afterswelling of less than several nanometres, which raises difficulties in analysis of the swelling stage,and hence the exfoliation mechanism as a whole.Now Takayoshi Sasaki and colleagues at the International Center for Materials Nanoarchitectonicsat the National Institute for Materials Science and the Fukuoka Institute of Technology in Japanhave realized up to 100-fold swelling of layered protonic oxides, otherwise known as solid acids,without exfoliation, by exposure to an aqueous amine solution. Adding HCl reduced them to theiroriginal size. Notably, in the process, more than 3000 molecular sheets, which make up thestarting crystal, instantly move apart and return together in a manner similar to springing pokercards.Unlike previously reported swelling or exfoliation, in which crystals swell far less before exfoliation,the swollen structures produced by exposure to the amine solution remained stable even whenshaken. The researchers discuss the stability using molecular dynamics calculations. “Unlike therandom H2O in the previously reported swollen phases that could be easily exfoliated, long-rangestructuring of the H2O molecules in the highly swollen structure was suggested using first-principlecalculations.” The observations also provide important insights into the physics of these systems.Reference"Unusually stable ~100-fold reversible and instantaneous swelling of inorganic layered materials"Fengxia Geng, Renzhi Ma, Akira Nakamura, Kosho Akatsuka, Yasuo Ebina, Yusuke Yamauchi,Nobuyoshi Miyamoto, Yoshitaka Tateyama, and Takayoshi SasakiJournal : Nature Communications 4, 1632 (2013).DOI : 10.1038/ncomms2641AffiliationsInternational Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for MaterialsScience (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, JapanContact informationInternational Center for Materials Nanoarchitectonics(WPI-MANA)National Institute for Materials Science1-1 Namiki, Tsukuba, Ibaraki 305-0044 JapanPhone: +81-29-860-4710E-mail: mana-pr[AT]ml.nims.go.jphttps://samurai.nims.go.jp/profiles/ma_renzhi?locale=enhttps://samurai.nims.go.jp/profiles/ebina_yasuo?locale=enhttps://samurai.nims.go.jp/profiles/yamauchi_yusuke?locale=enhttps://samurai.nims.go.jp/profiles/sasaki_takayoshi?locale=enhttps://www.nature.com/articles/ncomms26412022/04/04 10:27 Inorganic materials display massive and instantaneous swelling and shrinkage| MANAhttps://www.nims.go.jp/mana/research/highlights/vol6.html 3/3