Effect of viscoelasticity on the spherical and flat adhesion characteristics of photopolymerizable acrylate polymer networks

Lakhera, Nishant; Graucob, Annalena; Schneider, Andreas; Kroner, Elmar; Arzt, Eduard; Yakacki, Christopher M.; Frick, Carl P.

doi:10.1016/j.ijadhadh.2013.02.016

Cited by 24 publications

(21 citation statements)

References 47 publications

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“…Consequently, with a nonzero rate of deformation, the energy dissipation becomes much higher in the liquid crystal phase. Importantly, these viscoelastic properties are shown to have a close relationship with the performance of adhesives . As they can vary sharply across the nematic–isotropic transition in LCE, we expect them to alter the adhesion characteristics as well.…”

Section: Comparison Of Reconfigurable Adhesion Systems (Nonsolvent)mentioning

confidence: 95%

“…The dynamic mechanical analysis (DMA) tests also show large values of tan δ at low temperatures, which corresponds to the glass transition region (Figure ). Although it is tempting to follow the previous logic, and suggest that the glass transition region is also useful to increase adhesion, in practice, this is not the case. There is a lot of literature in the general field of pressure sensitive adhesives, where the scaling gauge is developed to estimate the performance of materials.…”

Section: Comparison Of Reconfigurable Adhesion Systems (Nonsolvent)mentioning

confidence: 99%

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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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Section: Comparison Of Reconfigurable Adhesion Systems (Nonsolvent)mentioning

confidence: 95%

Section: Comparison Of Reconfigurable Adhesion Systems (Nonsolvent)mentioning

confidence: 99%

Enhanced Dynamic Adhesion in Nematic Liquid Crystal Elastomers

2019

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“…Indeed, Castellanos et al have recently highlighted the polymer viscoelasticity property as a key parameter for the designing of bio‐inspired dry adhesive. Indeed, it is reported that without bulk or interfacial viscoelasticity, pillars are unable to make close contact with the counter surface, resulting in poor adhesion …”

Section: Resultsmentioning

confidence: 99%

Bio-Inspired Nanopatterned Polymer Adhesive: A Novel Elaboration Method and Performance Study

Moreno‐Couranjou¹,

Blondiaux

Pugin

et al. 2014

Plasma Process. Polym.

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The objective of this work is to investigate a novel top-down synthesis route toward the elaboration of nanopatterned polymer surfaces by combining thin polymer structuring (polymerdemixing) and plasma etching techniques. Thanks to this original approach, the adjustment of the parameters during the wet chemical and plasma steps allows independent tuning of the lateral dimension of the polymer structures (diameter) and the height of the pillars. The nanopatterning description of two different polymers, namely polyethylene naphthalate and polyimide, is reported. Johnson-Kendall-Roberts (JKR) adhesion tests are carried out to compare the adhesive property of the patterned and non-patterned polymer surfaces. These measurements allow highlighting the importance of the polymer viscoelasticity for future development of bioinspired polymer-based dry adhesives.

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“…It is considered that cooling time after pressing is required to shorten because the shortening is one of the most effective way to reduce manufacturing time for productivity. However, the requirement may increase adhesion between mold and thermoplastic CFRP because of high adhesion of thermoplastic resin at high temperature, especially around glassy-transition temperature [16,17]. This tendency is explained by some reports which show that viscoelastic behaviour of thermoplastic resin is dominant at higher temperature [18,19].…”

Section: Introductionmentioning

confidence: 99%

Effect of Electric Field on Adhesion of Thermoplastic Resin against Steel Plate

et al. 2017

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This work shows new method which controls adhesion strength between acrylic resin and metal mold with electric field. Usage of electric field is considered as a new solution to control adhesion of thermoplastic resin in Carbon-Fiber-Reinforced ThermoPlastic (thermoplastic CFRP) stamping process because this method can prevent CFRP from its degradation. In this work, we establish new adhesion tester which can apply Direct Current (DC) or Alternating Current (AC) field on metal specimens. In the results, when DC −12 V/mm is imposed on metal specimens, adhesion strength increases to 0.81 MPa which is 57% higher than that of no field condition. Negative component of surface energy after imposing DC −12 V/mm on metal specimens is 7.6 mJ/m 2 . This value is 56% smaller than that of no field condition. When AC electric fields is imposed, adhesion strength decreases from no electric field condition. The most effective AC field condition is AC 10 V/mm with 1 MHz, in which case adhesion strength is 0.29 MPa. This value is 44% lower than that of no field condition.

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Effect of viscoelasticity on the spherical and flat adhesion characteristics of photopolymerizable acrylate polymer networks

Cited by 24 publications

References 47 publications

Enhanced Dynamic Adhesion in Nematic Liquid Crystal Elastomers

Enhanced Dynamic Adhesion in Nematic Liquid Crystal Elastomers

Bio-Inspired Nanopatterned Polymer Adhesive: A Novel Elaboration Method and Performance Study

Effect of Electric Field on Adhesion of Thermoplastic Resin against Steel Plate

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