Bending, curling, and twisting in polymeric bilayers

Wisinger, Catherine E.; Maynard, Leslie A.; Barone, Justin R.

doi:10.1039/c9sm00268e

Cited by 18 publications

(23 citation statements)

References 45 publications

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“…Alternatively, such resonant phenomena could initiate the bending or the twisting 15 A c c e p t e d m a n u s c r i p t in multilayers thermoplastic polymers [32] or favor the return to equilibrium of shape memory polymers [33]. This thickness variation is reversible.…”

Section: Discussionmentioning

confidence: 99%

Resonant vibration of a thin polymer film under optical excitation

Émile

Gaudriault

2021

Soft Matter

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Section: Discussionmentioning

confidence: 99%

Resonant vibration of a thin polymer film under optical excitation

Émile

Gaudriault

2021

Soft Matter

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“…Various works have been inspired by biological principles to generate self‐winding as a response to external stimuli; however, most of them focus on the design of bilayers with mismatching properties. [ 11,13–15 ] Usually, the precursor is a flat ribbon or a straight rod formed by two layers with differential responses to stimuli. [ 3,16 ] However, simple formulation and production methods that mimic the spontaneous nature of self‐coiling are still lacking.…”

Section: Figurementioning

confidence: 99%

“…When a bilayer (precisely designed with mismatching elastic properties) is stretched and released, bending occurs preferentially toward the direction with the smallest Young's modulus. [ 14 ] For wires with asymmetric core–shell cross‐sections, Young's modulus gradient, and differential strain, it is nearly impossible to determine a preferential direction for bending upon swelling due to system complexity. It is important to remark that the reference pure gelatin wires also have asymmetric cross‐sections and are collected upon drawing.…”

Section: Figurementioning

confidence: 99%

Self‐Winding Gelatin–Amyloid Wires for Soft Actuators and Sensors

et al. 2020

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microfibrils are embedded. [10] These structures, which resemble artificial fiber-reinforced composites, deform largely along the alignment of the microfibrils, and deformation perpendicular to this reinforcement occurs less strongly. [11] This differential deformation is then transferred to macroscopic shape-shifting mechanisms such as self-winding. Self-winding is a competition between bending and twisting, which often stems from a need to release potential energy present in surface stresses, misfit strains, residual strains, thermal stresses, differential growth, shrinkage, or swelling. [12] Understanding these mechanisms is of fundamental importance to gaining insights into the design and application of helical shapes. Various works have been inspired by biological principles to generate self-winding as a response to external stimuli; however, most of them focus on the design of bilayers with mismatching properties. [11,13-15] Usually, the precursor is a flat ribbon or a straight rod formed by two layers with differential responses to stimuli. [3,16] However, simple formulation and production methods that mimic the spontaneous nature of self-coiling are still lacking. Here, we present a new fabrication approach that originates spontaneously self-winding wires upon their differential swelling in water. We apply biomimetic concepts to designing gelatin wires that are reinforced by amyloid fibrils (AFs) following principles similar to fiber-reinforced composites. Our fabrication dry-spins a single phase, thus bypassing the need for precise bilayer design and offering an easy, scalable, and sustainable alternative to more complex material designs. We employ β-lactoglobulin (BLG) to form AFs because of its rich and chiral structure. Although amyloid fibrils have promising properties, they alone cannot be processed as biopolymers because of their high rigidity and low plasticity. Therefore, we combine the plasticity of gelatin with the rigidity and versatile functionalization of AFs to produce wires that spontaneously self-wind in water. We investigate the origins of self-winding mechanisms by modeling the relative contributions of twisting and winding to the free energy. Finally, we explore the potential applications of such self-wound wires in sensors and actuators and complement our experimental results with theoretical interpretations. The wires disclosed here are, to the best of our knowledge, the first example of a system that is capable of performing as both actuator and sensor, produced entirely

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“…In fact, despite substantial studies regarding various buckling-associated patterns in viscous or viscoelastic fluid flows, e.g. folding (Ribe 2003;Pan, Phani & Green 2020), bending (Ribe 2001;Teichman & Mahadevan 2003;Tian et al 2020), twisting (Charles, Gazzola & Mahadevan 2019;Wisinger, Maynard & Barone 2019), deflecting (Brun et al 2015), etc., many aspects and patterns in the buckling problem of viscoplastic fluids remain obscure.…”

Section: Introductionmentioning

confidence: 99%

From breakup to coiling and buckling regimes in buoyant viscoplastic injections

Akbari

Taghavi

2022

J. Fluid Mech.

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We study the injection flow of a heavy viscoplastic fluid into a light Newtonian fluid, via modelling and experiments. The injection is carried out downward, via an eccentric inner pipe inside a vertical closed-end outer pipe. This configuration results in a core viscoplastic fluid surrounded by an annular Newtonian fluid. The flow is structured and mixing is negligible. As the injection rate increases in a typical experiment, we observe three distinct flow regimes, associated with the core fluid behaviour, namely the breakup, coiling and buckling (bulging) regimes. In the breakup regime, the core fluid is yielded due to the extension caused by buoyancy, while in the buckling regime the yielding occurs due to the compression promoted by the pressure and the interfacial shear stress applied by the upward flow of the annular fluid. For the coiling regime, the core fluid remains largely unyielded until it exhibits a coiling behaviour. We develop a lubrication approximation model, using the Herschel–Bulkley constitutive equation, with dimensionless flow parameters including the Bingham number, the power-law index, the buoyancy number, the viscosity ratio, the diameter ratio, the eccentricity and the aspect ratio. Based on a reasonable prediction to the yielding onset, the model allows us to classify the flow regimes versus an elegant combination of the dimensionless numbers.

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Bending, curling, and twisting in polymeric bilayers

Abstract: Polyolefin thermoplastic elastomer (POE) bilayers can be pulled and released to form helices without the use of directional anisotropy in the layers.

Cited by 18 publications

References 45 publications

Resonant vibration of a thin polymer film under optical excitation

Resonant vibration of a thin polymer film under optical excitation

Self‐Winding Gelatin–Amyloid Wires for Soft Actuators and Sensors

From breakup to coiling and buckling regimes in buoyant viscoplastic injections

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