Compositional Tuning Reveals a Pathway to Achieve a Strong and Lubricious Double Network in Agarose-Polyacrylamide Hydrogels

Shoaib, Tooba; Prendergast, Paige; Espinosa‐Marzal, Rosa M.

doi:10.1007/s11249-022-01604-4

Cited by 4 publications

(5 citation statements)

References 61 publications

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“…The scaling exponents found here are similar to those of other DN hydrogels . Shoaib et al prepared DN hydrogels composed of agarose and polyacrylamide (AgPAAm) in water-DMSO mixtures . Using an analogous setup to ours, they found power law exponents ranging from 0.52 to 0.61.…”

Section: Resultssupporting

confidence: 85%

“…2 Shoaib et al prepared DN hydrogels composed of agarose and polyacrylamide (AgPAAm) in water-DMSO mixtures. 23 Using an analogous setup to ours, they found power law exponents ranging from 0.52 to 0.61. The partially collapsed gel in 50% DMSO exhibited a lower exponent compared to water, as we also found for KCl compared to water, but our exponents are smaller.…”

Section: Lubrication Mechanismsmentioning

confidence: 59%

“…Interestingly, the frictional characteristics were convoluted by a binary response arising from the solvent viscosity and the polymer network at the surface. The heterogeneous surface structure originating from the DN seemed to spatially influence friction as well . This finding calls for a characterization method of the frictional response of heterogeneous DNs.…”

Section: Introductionmentioning

confidence: 91%

“…After removing the delaminated top surface, its subsurface exhibited a friction coefficient of 0.02 in gel-on-glass. 22 Shoaib et al 23 investigated the microstructure−property relationship of agarose-polyacrylamide DN hydrogels. Mechanical strengthening of the DN hydrogel over its individual components required a delicate balance between monomer concentration and crosslinking density.…”

Section: Introductionmentioning

confidence: 99%

“…The heterogeneous surface structure originating from the DN seemed to spatially influence friction as well. 23 This finding calls for a characterization method of the frictional response of heterogeneous DNs.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Intrinsic and Extrinsic Tunability of Double-Network Hydrogel Strength and Lubricity

Lee

Espinosa‐Marzal

2023

ACS Appl. Mater. Interfaces

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Double-network (DN) hydrogels are promising materials for tissue engineering due to their biocompatibility, high strength, and toughness, but understanding of their microstructure−property relationships still remains limited. This work investigates a DN hydrogel comprising a physically crosslinked agarose, as the first network, and a chemically crosslinked copolymer with a varying ratio of acrylamide and acrylic acid, as the second network. The charge, intrinsic to most DN hydrogels, introduces a responsive behavior to chemical and electrical stimuli. The DN strengthens agarose hydrogels, but the strengthening decreases with the swelling ratio resulting from increasing acrylic acid content or reducing salt concentration. Through careful imaging by atomic force microscopy, the heterogenous surface structure and properties arising from the DN are resolved, while the lubrication mechanisms are elucidated by studying the heterogeneous frictional response to extrinsic stimuli. This method reveals the action of the first (agarose) network (forming grain boundaries), copolymer-rich and poor regions (in grains), charge and swelling in providing lubrication. Friction arises from the shear of the polymeric network, whereas hydrodynamic lift and viscoelastic deformation become more significant at higher sliding velocities. We identify the copolymer-rich phase as the main source of the stimulus-responsive behavior. Salt concentration enhances effective charge density and reduces viscoelastic deformation, while electric bias swells the gel and improves lubrication. This work also demonstrates the dynamic control of interfacial properties like hydrogel friction and adhesion, which has implications for other areas of study like soft robotics and tissue replacements.

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Section: Resultssupporting

confidence: 85%

Section: Lubrication Mechanismsmentioning

confidence: 59%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Intrinsic and Extrinsic Tunability of Double-Network Hydrogel Strength and Lubricity

Lee

Espinosa‐Marzal

2023

ACS Appl. Mater. Interfaces

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Responsiveness of Charged Double Network Hydrogels to Ionic Environment

Lee,

Shrotriya,

Espinosa‐Marzal

2024

Adv Funct Materials

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Charged double network (DN) hydrogels are widely studied for their desirable mechanical strength and tunable properties. In this work, the influence of polymer concentration on microstructure and properties of agarose/polyacrylic acid DN hydrogels is studied. Agarose, the first network, is a brittle biopolymer, while polyacrylic acid (PAAc) is a weak polyelectrolyte. The microstructure, visualized in liquid environment, displays an agarose scaffold coated and interconnected by PAAc, deviating from the common assumption of an entangled double network. Importantly, the charging of PAAc in the hydrogel is regulated not only by the pH and weak polyelectrolyte effects, but also by the restricted swelling of the double network, and hence, it is an inherent regulation mechanism of charged hydrogels. The interactions between the hydrogel and the ionic environment induce microstructural changes and charging of the double network, impacting surface properties such as topography, stiffness, and adhesion, which are spatially resolved by liquid‐environment atomic force microscopy. The responsiveness of the DN hydrogels significantly depends on both polymer concentrations and ion concentrations. These findings provide insights into the responsive behavior of double network hydrogels and reveal universal mechanisms for charged hydrogels, which can guide the future development of functional soft materials.

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State-of-art functional nature-inspired surface modification strategies for combat biomedical biofouling: Challenges and new opportunities

Ali,

Fahad,

Amin

et al. 2025

Progress in Organic Coatings

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Compositional Tuning Reveals a Pathway to Achieve a Strong and Lubricious Double Network in Agarose-Polyacrylamide Hydrogels

Cited by 4 publications

References 61 publications

Intrinsic and Extrinsic Tunability of Double-Network Hydrogel Strength and Lubricity

Intrinsic and Extrinsic Tunability of Double-Network Hydrogel Strength and Lubricity

Responsiveness of Charged Double Network Hydrogels to Ionic Environment

State-of-art functional nature-inspired surface modification strategies for combat biomedical biofouling: Challenges and new opportunities

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