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Title: Reversible monolayer-to-crystalline phase transition in amphiphilic silsesquioxane at the air-water interface

We report on the counter intuitive reversible crystallisation of two-dimensional monolayer of Trisilanolisobutyl Polyhedral Oligomeric SilSesquioxane (TBPOSS) on water surface using synchrotron x-ray scattering measurements. Amphiphilic TBPOSS form rugged monolayers and Grazing Incidence X-ray Scattering (GIXS) measurements reveal that the in-plane inter-particle correlation peaks, characteristic of two-dimensional system, observed before transition is replaced by intense localized spots after transition. The measured x-ray scattering data of the non-equilibrium crystalline phase on the air-water interface could be explained with a model that assumes periodic stacking of the TBPOSS dimers. These crystalline stacking relaxes upon decompression and the TBPOSS layer retains its initial monolayer state. The existence of these crystals in compressed phase is confirmed by atomic force microscopy measurements by lifting the materials on a solid substrate.
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3]
  1. Saha Inst. of Nuclear Physics (India)
  2. Univ. du Maine (France)
  3. Univ. of Chicago, IL (United States). Center for Advanced Radiation Sources (CARS)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 5; Journal ID: ISSN 2045-2322
Nature Publishing Group
Research Org:
Univ. of Chicago, IL (United States). Center for Advanced Radiation Sources (CARS), Argonne National Laboratory (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE; USDOE Office of Science (SC)
Country of Publication:
United States