The development of protective covers for flexible displays requires a combination of properties that are often found to be incompatible with each other. In this context, it has been particularly challenging to simultaneously obtain glass-like wear resistance, plastic-like flexibility, and high optical transparency.

Dongchan Jang and Byeong-Soo Bae, Korea Advanced Institute of Science and Technology (KAIST), Daejon, Republic of Korea, and colleagues have used a molecular hybridization approach to successfully address this problem. First, the researchers synthesized a highly cross-linked cycloaliphatic epoxy-functionalized oligosiloxane (CEOS), in which a ladder-like silsesquioxane is the predominant species. The CEOS building blocks were then polymerized via the epoxy groups by a combination of UV curing and moisture annealing.

The team applied a 50 µm thick coating of their material to a plastic film, which yielded a bendable composite (10,000 bending cycles without fracture) with outstanding wear resistance. The researchers attribute the performance of their material to the inorganic-organic hybrid structure and highlight the simplicity of their method, as well as the possibility to scale up the synthesis.

• Flexible Hard Coating: Glass-Like Wear Resistant, Yet Plastic-Like Compliant, Transparent Protective Coating for Foldable Displays,
  Gwang-Mun Choi, Jungho Jin, Dahye Shin, Yun Hyeok Kim, Ji-Hoon Ko, Hyeon-Gyun Im, Junho Jang, Dongchan Jang, Byeong-Soo Bae,
  Adv. Mater. 2017.
  DOI: 10.1002/adma.201700205