No abstract

An elastic film with water repellency is of great interest for application to waterproof and antifouling surface treatment of stretchable devices such as wearable electronics or functional textiles. Herein, a nanoscale ultrathin stretchable polymer film endowed with superhydrophobicity was newly designed and synthesized by a vapor phase method, initiated chemical vapor deposition (iCVD). The highly stretchable superhydrophobic polymer film was generated from the copolymerization of 1H,1H,2H,2H-perfluorooctyl acrylate (PFOA) and 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane (V3D3) to form a cross-linked fluoropolymer network with low crystallinity and elasticity as well as superhydrophobicity. The composition of the copolymer film was adjusted by controlling the flow rates of the input monomers of PFOA and V3D3 during the deposition process. The copolymer film with the optimized composition showed an elastic limit higher than 200% while maintaining the superhydrophobic property with a water contact angle greater than 150°on nonflat substrates. An 800-nm-thick copolymer thin film showed mechanical durability with superhydrophobic performance even after 2000 cycles of a 200% stretch test. The elastic copolymer film also displayed solvent resistance against incubation in various organic solvents for 24 h. Transparency greater than 90% was also confirmed in the whole visible range with large-area uniformity and conformal coverage. We believe the stretchable superhydrophobic polymer film developed in this study is a promising candidate material for passivation of various stretchable device applications.

Transition metal dichalcogenides (TMDs) have attracted significant interest as gas‐sensing materials due to their unique crystal structure and surface. However, there are still issues when it comes to expanding the types of sensing gases for the TMD gas sensors. To extend gas‐sensing selectivity for the TMD gas sensors in this study, a monolayer (ML) 2D metal–organic framework (MOF) is introduced on top of the PtSe2 gas sensor, thereby tuning the major sensing analyte of PtSe2 from NO2 to H2S. Density functional theory calculations elucidate that the metal species of ML MOFs are attributed to the tuned selectivity of the analytes, based on the difference in binding energies. It is also demonstrated that ML MOF maintained the high responsivity of the pristine PtSe2 even at a low concentration of gas (200 ppb). This is further confirmed through the molecular dynamics simulations, which reveal that the ML feature of the ML MOF is highly essential to preserve the intrinsic ultra‐low limit detection properties of pristine PtSe2.

MOF-on-MOF is attracting great attention due to its improved and/or synergistic properties not exhibited in a single MOF. In particular, the non-isostructural pairs of MOF-on-MOFs can have great potentials induced...

Recent developments in wearable and embeddable electronic devices in physiological condition, such as neuroprobe and electroceuticals, have brought forth the need for a reliable passivation layer against water permeation into the devices. On top of the excellent waterproof barrier performance, the passivation layers must also be equipped with stretchability and dermatoid softness for the reliable operation of the devices without failure in the wet environment. Here, this work demonstrates a stretchable, superhydrophobic coating with excellent water barrier performance. The stretchable water barrier coating is formed by depositing alternating layers of a highly stretchable, superhydrophobic copolymer and a crosslinked organosiloxane polymer via initiated chemical vapor deposition. During the deposition, the organosiloxane polymer penetrates into the free volume of superhydrophobic copolymer to form a highly mixed network at the interface. Accordingly, a five‐layered coating shows excellent water and molecular barrier performance with no sign of degradation even at 60% of tensile strain. Moreover, this barrier film formed by vapor deposition is uniformly deposited on the substrate surface regardless of the type and morphology of the substrate. The highly stretchable water barrier coating developed in this study will serve as a promising candidate material for the passivation of various stretchable device applications.