Foldable and Extremely Scratch-Resistant Hard Coating Materials from Molecular Necklace-like Cross-Linkers

Jiae Seo, Sung Wook Moon, Heemin Kang, Byoung Ho Choi, Ji Hun Seo

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


A flexible hard coating material displaying extreme scratch resistance and foldable flexibility was developed via the design of an organic-inorganic hybrid coating material employing an alkoxysilyl-functionalized polyrotaxane cross-linker (PRX-Si1). PRX-Si1 has a molecular necklace-like structure that can form organic-inorganic cross-linking points and provide large molecular movements. It was postulated that the scratch resistance and flexibility could be simultaneously increased because of the hybrid cross-linking points and dynamic molecular movements. To confirm this hypothesis, the crystalline structure and mechanical properties of the PRX-Si1-based hard coating material were analyzed via transmission electron microscopy, small-angle X-ray diffraction, tensile, pencil hardness, and scratch tests. Finally, the PRX-Si1-based hard coating material could form homogeneously dispersed nanoscale siloxane crystalline domains, and the strain at the break point was 3 times higher than that of a commercial hard coating material, resulting in no defect formation even after 5000 folding test runs. Moreover, the material displayed extremely high pencil hardness (9H) and scratch resistance.

Original languageEnglish
Pages (from-to)27306-27317
Number of pages12
JournalACS Applied Materials and Interfaces
Issue number30
Publication statusPublished - 2019 Jul 31

Bibliographical note

Funding Information:
This research was partially supported by the KCC Research Institute and Korea University-Future Research Unit (K1822141). This research was also supported by the X-Project, funded by the National Research Foundation, Republic of Korea (NRF-2018R1E1A2A02086660).

Publisher Copyright:
© 2019 American Chemical Society.


  • antiscratch
  • coating material
  • cross-linker
  • hybrid
  • polyrotaxane
  • siloxane

ASJC Scopus subject areas

  • General Materials Science


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