A versatile wrinkle‐based micropatterned system with a film‐substrate structure is proposed, which contains a hydrophilic film of polyvinyl alcohol or its composite with laponite and a hydrophobic substrate of polydimethylsiloxane or its composite with carbon black. The wrinkled system features high design flexibility and multistimuli responsiveness, which can be activated by various mechanical methods, including vertical press or scratch, gentle stretch‐and‐release, bend, or analogous magneto‐mechanical and electro‐mechanical modes. The resultant wrinkles possess 1) instantaneous and reversible strain/moisture/light responsive optical modulation; 2) tunable dynamics for the aforementioned strain/moisture/light response;3) tailorable amplitude/wavelength; 4) unique surface morphologies from the coupling of wrinkles and cracks; 5) excellent reversibility and durability. A variety of applications are demonstrated based on this system, including 1) a moisture erasable highly sensitive pressure responsive device and pattern replicator with a high fidelity; 2) a moisture erasable scratch/magneto‐mechanical re‐writable tablet; 3) an electro‐mechanical controllable smart window with an ultra‐sensitive strain responsive transmittance modulation and a low operating voltage; 4) various types of strain responsive, moisture erasable, and laser writable information recording/encryption devices. This work provides new routes for designing innovative wrinkled systems triggered by diverse mechanical fashions and can decode multiple environmental stimuli into optical signals for widespread application.
Ghost fishing, caused by lost fishing lines and nets,
has become
a severe problem in marine environments. To eliminate ghost fishing
in the ocean, the environmental degradation behavior of fishing lines
must be understood. In this study, the environmental degradation of
biodegradable nylon 4 fishing lines and commercial nylon 6, poly(ethylene
terephthalate) (PET), and poly(vinylidene fluoride) (PVDF) fishing
lines was simulated in the laboratory using an artificial weathering
tester
and biodegradation test in extracted seawater. To understand the degradation
mechanism, the chemical and structural changes induced by photo-oxidation
and biodegradation were investigated using tensile test, scanning
electron microscopy, differential scanning calorimetry, gel permeation
chromatography, infrared spectroscopy, and wide- and small-angle X-ray
scattering. The results indicated that photo-oxidation occurred in
the amorphous phase of the nylon 4, nylon 6, and PET fishing lines
during ultraviolet (UV) exposure. The nylon 4 fishing lines exhibited
excellent biodegradability, whereas the nylon 6, PET, and PVDF fishing
lines could not be degraded by microorganisms in the extracted seawater.
Both processes, i.e., photo-oxidation and biodegradation, were confined
to the amorphous regions of nylon 4. Note that the PVDF fishing lines
could not be degraded by UV exposure and biodegradation and, hence,
should be recycled after use.
Advances in mechanistic understanding of integrin-mediated adhesion highlight the importance of precise control of ligand presentation in directing cell migration. Top-down nanopatterning limited the spatial presentation to sub-micron placing restrictions on both fundamental study and biomedical applications. To break the constraint, here we propose a bottom-up nanofabrication strategy to enhance the spatial resolution to the molecular level using simple formulation that is applicable as treatment agent. Via self-assembly and co-assembly, precise control of ligand presentation is succeeded by varying the proportions of assembling ligand and nonfunctional peptide. Assembled nanofilaments fulfill multi-functions exerting enhancement to suppression effect on cell migration with tunable amplitudes. Self-assembled nanofilaments possessing by far the highest ligand density prevent integrin/actin disassembly at cell rear, which expands the perspective of ligand-density-dependent-modulation, revealing valuable inputs to therapeutic innovations in tumor metastasis.
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