A two-step method for fabricating large-area textile-embedded elastomers for tunable friction

Abstract

Recently, shape-tunable wrinkles formed on an elastomeric sheet with a textile finely embedded in proximity to the surface have been developed for in situ control of friction depending on various situations. For their actual uses, sheets with a large area are desired. A key challenge on their fabrication is to overcome the non-uniformity of the vertical position of the textile embedded within the elastomeric sheet, which causes substantial reduction in the tunable range of friction. The defect originates from the increased difficulty, as the sheet area is scaled up, of squeezing a viscoelastic precursor liquid due to the use of a deformable elastomeric surface. Here, we report a new two-step method for a textile-embedded elastomeric sheet that avoids using the soft elastomeric surface on the squeezing process and requires post-joining to an elastomeric base sheet. The obtained sheet with a large area (180 × 180 mm), was uniform and showed a large change of friction on its strain-induced transformation between flat and wrinkled states. The relationship between the experimentally controllable parameters and the squeeze film hydrodynamics is theoretically discussed, which is generally applicable to precise embedding micro-objects at the elastomer surface.

Dynamic Manipulation of Friction in Smart Textile Composites of Liquid‐Crystal Elastomers

“…The mixture was kept between two glass slides with a textile mesh with thickness of ≈0.1 mm at 70 °C (isotropic phase) overnight under a pressure of ≈10 kPa applied to the direction normal to the glass surface to squeeze out the excess liquid. [ 31 ] The sample was released from the glass mold, and placed at 80 °C in vacuum to remove the solvent. The sample was then cooled down to RT and UV light (365 nm) was applied for 20 min under a uniaxial tensile strain to finalize the crosslinking between the rest of the acrylates.…”

“…After the mixture was gently mixed at an elevated 𝑇 ~70°C for ~10 min, TEA was added at 1.5wt% to start the Michael-addition reaction between thiol and acrylate groups. The mixture was kept between two glass slides with a textile mesh with thickness of ~0.1 mm at 70°C (isotoropic phase) overnight under a pressure of ~10 kPa applied to the direction normal to the glass surface to squeese out the excess liquid [31] . The sample was released from the glass mold, and placed at 80°C in vacuum to remove the solvent.…”

“…The fabrication of the composite begins with molding the LCE precursor and the textile sheet between two flat glass slides under normal pressure, [ 31 ] and its thermal curing in the isotropic phase (Figure 1a, Methods). The first thiol‐ene reaction, creates a random isotropic polymer network.…”