Shaping micro-clusters via inverse jamming and topographic close-packing of microbombs

Seunggun Yu, Hyesung Cho, Jun Pyo Hong, Hyunchul Park, Jason Christopher Jolly, Hong Suk Kang, Jin Hong Lee, Junsoo Kim, Seung Hwan Lee, Albert S. Lee, Soon Man Hong, Cheolmin Park, Shu Yang, Chong Min Koo

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Designing topographic clusters is of significant interest, yet it remains challenging as they often lack mobility or deformability. Here we exploit the huge volumetric expansion (up to 3000%) of a new type of building block, thermally expandable microbombs. They consist of a viscoelastic polymeric shell and a volatile gas core, which, within structural confinement, create micro-clusters via inverse jamming and topographical close-packing. Upon heating, microbombs anchored in rigid confinement underwent balloon-like blowing up, allowing for dense clusters via soft interplay between viscoelastic shells. Importantly, the confinement is unyielding against the internal pressure of the microbombs, thereby enabling self-assembled clusters, which can be coupled with topographic inscription to introduce structural hierarchy on the clusters. Our strategy provides densely packed yet ultralight clusters with a variety of complex shapes, cleavages, curvatures, and hierarchy. In turn, these clusters will enrich our ability to explore the assemblies of the ever-increasing range of microparticle systems.

Original languageEnglish
Article number721
JournalNature communications
Issue number1
Publication statusPublished - 2017 Dec 1

Bibliographical note

Funding Information:
This work was supported by Fundamental R&D Program for Core Technology of Materials and the Industrial Strategic Technology Development Program funded by the Ministry of Trade, Industry and Energy, Republic of Korea. This work was also partially funded by Korea Institute of Science and Technology through Young Fellow program. This research was also supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning. This research was also supported by a grant from the Disaster and Safety Management Institute funded by the Ministry of Public Safety and Security of Korea government. S.Y. acknowledges support from National Science Foundation (NSF) Emerging Frontiers in Research and Innovation-Origami Design for Integration of Self-Assembling Systems for Engineering Innovation (NSF/EFRI-ODISSEI) Grant No. EFRI 13–31583.

Publisher Copyright:
© 2017 The Author(s).

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)


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