Stretchable
barrier films capable of maintaining high levels of
moisture- and gas-barrier performance under significant mechanical
strains are a critical component for wearable/flexible electronics
and other devices, but realization of stretchable moisture-barrier
films has not been possible due to the inevitable issues of strain-induced
rupturing compounded with moisture-induced swelling of a stretched
barrier film. This study demonstrates nanolaminated polymer/metal
oxide stretchable moisture-barrier films fabricated by a novel molecular
layer deposition (MLD) process of polyamide-2,3 (PA-2,3) integrated
with atomic layer deposition (ALD) metal oxide processes and an in
situ surface-functionalization technique. The PA-2,3 surface upon
in situ functionalization with H2O2 vapor offers
adequate surface chemisorption sites for rapid nucleation of ALD oxides,
minimizing defects at the PA-2,3/oxide interfaces in the nanolaminates.
The integrated ALD/MLD process enables facile deposition and precise
structural control of many-layered oxide/PA-2,3 nanolaminates, where
the large number of PA-2,3 nanolayers provide high tolerance against
mechanical stretching and flexing thanks to their defect-decoupling
and stress-buffering functions, while the large number of oxide nanolayers
shield against swelling by moisture. Specifically, a nanolaminate
with 72 pairs of alternating 2 nm (5 cycles) PA-2,3 and 0.5 nm HfO2 (five cycles) maintains its water vapor transmission rate
(WVTR) at the 10–6 g/m2 day level upon
10% tensile stretching and 2 mm-radius bending, a significant breakthrough
for the wearable/flexible electronics technologies.
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