Switchable bumps of a bead-embedded elastomer surface with variable adhesion

Ohzono, Takuya; Teraoka, Kay

doi:10.1039/c7sm02048a

Cited by 9 publications

(8 citation statements)

References 27 publications

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“…[84][85][86][87][88][89][90][91][92][93][94][95][96][97][98] The switching of contact area has the potential Adv. [84][85][86][87][88][89][90][91][92][93][94][95][96][97][98] The switching of contact area has the potential Adv.…”

Section: Area Switching (A)mentioning

confidence: 99%

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Switchable Adhesives for Multifunctional Interfaces

Croll

Hosseini

Bartlett

2019

Adv Materials Technologies

125

107

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The reliable bonding or attachment of materials is critical in many industries, is a common necessity of daily life, and is key to functionality in numerous biological settings. [1][2][3][4][5][6][7][8][9][10][11] Adhesives Joining two materials with an adhesive is an extremely common activity, but is most often irreversible. However, emerging and current applications ranging from consumer and medical products to soft robotics and wearable bio-monitoring devices demand strong adhesives which can be easily removed on-demand and subsequently reused. This requires new paradigms in adhesive science and engineering, resulting in the emergence of new classes of multifunctional switchable adhesives. Here summarized is the current state of the art in switchable adhesive systems, focusing on how devices fit into the basic science of adhesion while providing performance metrics for comparison across current approaches. Using fracture mechanics as a guide, systems are classified as functioning under one of three basic mechanisms: near-interface, contact area, or mechanical. These mechanisms must be initiated or "triggered" by a specific input, which can include mechanical, electromagnetic, fluidic, or thermal stimuli. Triggers and adhesion switching performance are compared through the use of a "switching ratio," the interfacial energy release rate, and an estimate of mechanism timing. Finally, it is discussed that how the fundamental mechanisms relate to challenges and opportunities for switchable interfaces in future applications and adhesive systems.

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Section: Area Switching (A)mentioning

confidence: 99%

“…Controlling the amount of true surface contact is also a clear path toward switchable adhesion, which many designs have exploited. [84][85][86][87][88][89][90][91][92][93][94][95][96][97][98] The switching of contact area has the potential Adv. Mater.…”

Section: Area Switching (A)mentioning

confidence: 99%

Switchable Adhesives for Multifunctional Interfaces

Croll

Hosseini

Bartlett

2019

Adv Materials Technologies

125

107

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“…Many of them rely on the interfacial properties of the contact, such as surface topography and chemical functionality. The former directly affects the contact area A to be detached and, therefore, the adhesion can indeed be altered by changing the surface topography . The latter mainly affects the interfacial energy density via the bare surface tension of each material or chemical/physical bond/entanglements .…”

Section: Comparison Of Reconfigurable Adhesion Systems (Nonsolvent)mentioning

confidence: 99%

Enhanced Dynamic Adhesion in Nematic Liquid Crystal Elastomers

2019

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stimuli, including thermal, pH, electric, chemicals, etc. [3] Many of them rely on the interfacial properties of the contact, such as surface topography and chemical functionality. The former directly affects the contact area A to be detached and, therefore, the adhesion can indeed be altered by changing the surface topography. [4][5][6][7] The latter mainly affects the interfacial energy density via the bare surface tension of each material or chemical/physical bond/ entanglements. [8][9][10] However, less attention has been paid to the use of the bulk viscoelastic characteristics that are especially important in dynamic applications toward stimuli-responsive adhesives. [11,12] To our knowledge, no experimental study exists of the switchable adhesion of the nematic liquid crystal elastomers (LCEs), which possess unique bulk mechanical properties.LCEs are a unique class of elastomers, in which the nematic director is coupled to the polymer network in both static and dynamic manner. [13] In the macroscopically nonaligned LCE (called "polydomain"), the local uniaxial nematic order Q(T) develops in a usual manner of the frustrated first-order phase transition from the isotropic phase, [14] but the nematic regions of a characteristic size of a micrometer are randomly misaligned in the bulk material. As a result, the polydomain LCE is macroscopically isotropic, [15] but retains all its characteristic nematic LCE parameters (such as the elastic modulus and loss factor, both relevant to this study). In contrast, the aligned ("monodomain") nematic LCE shows the uniform macroscopic anisotropy Q(T) across the whole sample, and the characteristic effect of spontaneous shape change [16,17] on increasing temperature T across the nematic-isotropic transition temperature, T NI (often called "thermal actuation"). This effect makes LCE highly attractive for applications [13,[18][19][20][21][22] involving soft actuators, shape-memory materials, and others.The other unique characteristics of nematic LCE, on which we especially focus here, is the effect of "soft elasticity," which in dynamic-mechanical setting manifests itself in a large increase in the loss factor tanδ, and the decrease in the storage moduli E′ and G′. [13,[23][24][25] This effect shows a great potential in LCE as energy damping materials. [23,26] The higher internal viscosity originates from the additional nematic (orientational) interaction between polymer chains. This adds resistance against the local rotation of the liquid crystalline director relative to the network in response to the finite strain rate (similarly to the higher viscosity in the ordinary liquid crystals).

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“…Some of the applications have a potential need to control the friction and/or adhesion properties depending on the usage situations; the in situ switchability of friction/adhesion of the materials surface has been desired. Recently, we have proposed the use of the shape-tunable surfaces to change the contact state at the interface [17–21], and thus, to tune the friction and/or adhesion simply by varying lateral strain applied to the surface. The shape tunability has been realized by the buckling-based surface wrinkling [22].…”

Section: Introductionmentioning

confidence: 99%

“…Some of the applications have a potential need to control the friction and/or adhesion properties depending on the usage situations; the in situ switchability of friction/adhesion of the materials surface has been desired. Recently, we have proposed the use of the shapetunable surfaces to change the contact state at the interface [17][18][19][20][21], & 2018 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.…”

Section: Introductionmentioning

confidence: 99%

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

Ohzono

Teraoka²

2018

R. Soc. open sci.

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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.

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Switchable bumps of a bead-embedded elastomer surface with variable adhesion

Abstract: A composite material composed of an elastomer sheet and hard beads embedded at the surface realizing a shape-tunable surface.

Cited by 9 publications

References 27 publications

Switchable Adhesives for Multifunctional Interfaces

Switchable Adhesives for Multifunctional Interfaces

Enhanced Dynamic Adhesion in Nematic Liquid Crystal Elastomers

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

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