Tunable Friction Properties of Periodic Wrinkled BaTiO₃ Membranes

Abstract

The wrinkled patterns may find potential applications in the areas that require tunable friction properties, such as flexible electronics, nanomechanical systems, and biomedical devices. However, the regulation of wrinkled patterns and the influence of friction property remain poorly understood, especially in the field of oxides. The epitaxial wrinkled BaTiO3 (BTO) membranes are prepared by the pulsed laser deposition and water‐dissolution process. The patterns, amplitude, and wavelength of the wrinkled BTO membranes are dependent on the thickness, pre‐stretched mechanical stress, and heat treatment. The friction properties of the wrinkled BTO membranes exhibit various anisotropic and periodic features due to the varying wrinkled patterns as applying different mechanical stress, including anisotropy with 180° angular periodicity, anisotropy with 360° angular periodicity, and isotropy, corresponding to the parallel, zigzag, and labyrinth patterns, respectively. Moreover, the heat process can further alter the magnitude of the friction property, showing a downward trend with increasing temperature. These results provide a better understanding of the friction properties of wrinkled patterns and pave a novel way to alter the friction properties for extensive applications.

Retraction of “Three-Axial Strain-Triggered Multimode Wrinkles with Tuneable Frictional and Optical Performances”

“…Furthermore, we notice that the friction anisotropy for striped wrinkles (from ≈28 to ≈10 mV) is stronger than that for rippled wrinkles (from ≈30 to ≈50 mV). They are both much larger than the friction anisotropy of labyrinth-like and herringbone wrinkles according to the previous studies. − These results demonstrate that the frictional properties are well controllable by modulating the morphology and orientation of surface wrinkles. Finally it should be noted that the friction detected by the LMF imaging only provides the relative value.…”

“…A larger aspect ratio always means a larger surface slope and a higher friction force. 47,48 Furthermore, we notice that the aspect ratio decreases to nearly zero while the friction force remains a larger value at θ = 90°(see Figure 5d). This indicates that the friction force can be attributed to two factors.…”

Wrinkled Interfaces: Taking Advantage of Anisotropic Wrinkling to Periodically Pattern Polymer Surfaces

“…Such periodic wrinkles are described as “oriented wrinkles” and present a highly regular arrangement. [ 49 , 50 , 51 , 52 ] In terms of wrinkle distribution, other wrinkles without the periodic characteristic are disordered, they do not have any preferential orientation and display a random distribution. [ 53 , 54 , 55 ]…”

“…Such periodic wrinkles are described as "oriented wrinkles" and present a highly regular arrangement. [49][50][51][52] In terms of wrinkle distribution, other wrinkles without the periodic characteristic are disordered, they do not have any preferential orientation and display a random distribution. [53][54][55] In terms of shape, oriented wrinkles can be further subdivided, typically including parallel, [56][57][58] zigzag, [10,59,60] circular, [61,62] and regular polygons (tetragonal, hexagonal, etc.).…”

“…On the downside, a larger strain will yield more cracks and defects. [51,89,106,150,151] The intensity of the strain applied not only affects the dimensions but even the type of wrinkle pattern. [59,62,152] Some studies have shown that a film can buckle into different patterns ranging from checkerboard, herringbone, hexagonal, triangular, and even labyrinth patterns when subjected to uniaxial/biaxial compressive stresses.…”