Wrinkling on Covalently Anchored Hydrogels

Liaw, Chya‐Yan; Pereyra, Jorge; Guvendiren, Murat

doi:10.1007/978-3-030-05123-5_9

Cited by 8 publications

(7 citation statements)

References 58 publications

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“…The high α f values measured from 2.4 to 3.2 with our systems are above the critical threshold value reported for various hydrogel systems of α c ≈ 2 for the polyacrylamide, α c ≈ 1.12 for the PHEMA, and α c ≈ 2 for the poly(vinylpyrrolidone)/poly(acrylic acid) layer-by-layer system. In fact, there is a wide range of critical swelling values on the onset of surface instability reported experimentally, 2.0–3.7 in hydrogel material or a theoretical prediction from 2.5 to 3.4 . In the present work, the high swelling ratios indicate that surface buckling occurred easily upon swelling.…”

Section: Resultsmentioning

confidence: 45%

“…Wrinkle formation, in particular, is a strategy which has been developed to produce a microstructured surface in the submicrometer range − using a bilayer system composed of a rigid layer anchored on a soft plastic substrate. Such artificial wrinkling is generally based on elastic surface instabilities and the buckling effect due to compressive stress in soft cross-linked polymers including hydrogel materials, − solvent-responsive films, − and elastomers. − By taking advantage of this phenomena, the wrinkling of soft polymer surfaces and other alternatives have been developed to fabricate buckled structures involving various strategies , mostly consisting of swelling, drying, heating, or mechanical stretching/compression. A permanent wrinkling pattern can be achieved and stabilized through the diffusion and polymerization of reactive liquid monomers by silane-infusion-based wrinkling in poly(2-hydroxyethyl methacrylate) (PHEMA) .…”

Section: Introductionmentioning

confidence: 99%

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Growth-Induced Wrinkles and Dotlike Patterns of a Swollen Fluoroalkylated Thin Film by the Reaction of Surface-Attached Polymethylhydrosiloxane

Thami

Ramonda²,

Ferez

et al. 2022

Langmuir

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The design of hydrophobic surfaces requires a material which has a low solid surface tension and a simple fabrication process for anchoring and controlling the surface morphology. A generic method for the spontaneous formation of robust instability patterns is proposed through the hydrosilylation of a fluoroalkene bearing dangling chains, R f = C 6 F 13 (CH 2 ) 3 −, with a soft polymethylhydrosiloxane (PMHS) spin-coated gel polymer (0.8 μm thick) using Karstedt catalyst. These patterns were easily formed by an irreversible swelling reaction due to the attachment of a layer to various substrates. The buckling instability was created by two different approaches for a gel layer bound to a rigid silicon wafer substrate (A) and to a soft nonswelling silicone elastomer foundation (B). The observations of grafted R f -PMHS films in the swollen state by microscopy revealed two distinct permanent patterns on various substrates: dotlike of wavelength λ = 0.4−0.7 μm (A) or wrinkle of wavelength λ = 4−7 μm (B). The elastic moduli ratios of film/substrate were determined using PeakForce quantitative nanomechanical mapping. The characteristic wavelengths (λ) of the patterns for systems A and B were quantitatively estimated in relation to the thickness of the top layer. A diversity of wrinkle morphologies can be achieved by grafting different side chains on pristine PMHS films. The water contact angle (WCA) hysteresis of fluorinated chain (R f ) was enhanced upon roughening the surfaces, giving highly hydrophobic surface properties for water with static/hysteresis WCAs of 136°/74°in the resulting wrinkle (B) and 119°/41°in the dotlike of lower roughness (A). The hydrophobic properties of grafted films on A with various mixtures of hexyl/fluoroalkyl chains were characterized by static CA: WCA 104−119°, ethylene glycol CA 80−96°, and n-hexadecane CA 17− 61°. A very low surface energy of 15 mN/m for R f -PMHS was found on the smoother dotlike pattern.

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Section: Resultsmentioning

confidence: 45%

Section: Introductionmentioning

confidence: 99%

Growth-Induced Wrinkles and Dotlike Patterns of a Swollen Fluoroalkylated Thin Film by the Reaction of Surface-Attached Polymethylhydrosiloxane

Thami

Ramonda²,

Ferez

et al. 2022

Langmuir

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show abstract

“…For a detailed review of more experimental studies on pattern formations in gels, we refer to Dervaux and Amar [2012]. More recently, Liaw et al [2019] have elucidated the various mechanisms through which surface instability patterns are activated in confined hydrogels. Advancements in the field of controlled pattern generation in hydrogel systems that respond to a wide range of external stimuli such as changes in solvent concentration, temperature, electric field etc.…”

Section: Introductionmentioning

confidence: 99%

Transient stability analysis of composite hydrogel structures based on a minimization-type variational formulation

Sriram¹,

Polukhov²,

Keip³

2021

Preprint

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We employ a canonical variational framework for the predictive characterization of structural instabilities that develop during the diffusion-driven transient swelling of hydrogels under geometrical constraints. The variational formulation of finite elasticity coupled with Fickian diffusion has a two-field minimization structure, wherein the deformation map and the fluid-volume flux are obtained as minimizers of a time-discrete potential involving internal and external energetic contributions. Following spatial discretization, the minimization principle is implemented using a conforming Q 1 RT 0 finiteelement design, making use of the lowest-order Raviart-Thomas-type interpolations for the fluid-volume flux. To analyze the structural stability of a certain equilibrium state of the gel satisfying the minimization principle, we apply the local stability criterion on the incremental potential, which is based on the idea that a stable equilibrium state has the lowest potential energy among all possible states within an infinitesimal neighborhood. Using this criterion, it is understood that bifurcation-type structural instabilities are activated when the coupled global finite-element stiffness matrix loses its positive definiteness. This concept is then applied to determine the onset and nature of wrinkling instabilities occurring in a pair of representative film-substrate hydrogel systems. In particular, we analyze the dependencies of the critical buckling load and mode shape on the system geometry and material parameters.

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“…Three‐dimensional (3D) printing (additive manufacturing) is a relatively new, rapidly expanding method of manufacturing that allows the formation of 3D compact structures with desired and predefined architecture. The technique has been widely commercialized and applied successfully in many fields, including medical, [ 13 ] electronic, food, thermoelectric, [ 14 ] and automotive industries. [ 15 ] The products of additive manufacturing can be fabricated from many types of materials, including a wide range of polymers, metals, composites, [ 16,17 ] or natural products.…”

Section: Introductionmentioning

confidence: 99%

Preparation of antimicrobial 3D printing filament: In situ thermal formation of silver nanoparticles during the material extrusion

et al. 2020

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Many efforts have been made either to provide the typical three-dimensional (3D) printing materials with new and specific properties or to enhance their overall stability. The use of nanomaterials in 3D printing is gaining attention due to the tremendous functionality that this approach provides for those materials. This article presents a method of producing poly(lactic acid) (PLA)silver nanoparticle antibacterial filament for additive manufacturing. Polymer dope of silver salts within PLA was prepared by the solution-phase and solvent-less methods, followed by extrusion into filaments. Silver nanoparticles were synthesized in situ by thermal decomposition of silver salt during the thermal extrusion of the filament. The formation and dispersion of the nanoparticles within the polymer structure were examined and confirmed with transmission electron microscope and X-ray diffraction. The solution-phase method proposed in this study may prevent failure with nanoparticle dispersion occurring in melt blending. The filament was used for the fabrication of predesigned specimens for antimicrobial and mechanical testing. Printed objects exhibited antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. This study revealed that the incorporation of silver nanoparticles (0.01-5 wt%) into PLA does not significantly change its bulk properties but renders the composite antibacterial. The

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Wrinkling on Covalently Anchored Hydrogels

Cited by 8 publications

References 58 publications

Growth-Induced Wrinkles and Dotlike Patterns of a Swollen Fluoroalkylated Thin Film by the Reaction of Surface-Attached Polymethylhydrosiloxane

Growth-Induced Wrinkles and Dotlike Patterns of a Swollen Fluoroalkylated Thin Film by the Reaction of Surface-Attached Polymethylhydrosiloxane

Transient stability analysis of composite hydrogel structures based on a minimization-type variational formulation

Preparation of antimicrobial 3D printing filament: In situ thermal formation of silver nanoparticles during the material extrusion

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