Water-Triggered Ductile–Brittle Transition of Anisotropic Lamellar Hydrogels and Effect of Confinement on Polymer Dynamics

Ilyas, Muhammad; Haque, Md. Anamul; Yue, Youfeng; Kurokawa, Takayuki; Nakajima, Tasuku; Nonoyama, Takayuki; Gong, Jian Ping

doi:10.1021/acs.macromol.7b01438

Cited by 31 publications

(21 citation statements)

References 34 publications

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“…However, when C SA exceeded 10 wt%, the relationship of E ∼ C v,p 3 was observed, no longer obeying the rubber elasticity theory. It should be noted that the transition of two power law regions in this research is quite different from the water‐triggered ductile‐brittle transition reported by Gong and co‐workers owing to two reasons. First, the critical C W value relative to the modulus transition in the current work was ≈80 wt%, corresponding to a molar composition of water/G (or M) unit ≈ 40/1, which showed that more water molecules were hydrated in per G or M unit.…”

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confidence: 92%

Cooking‐Inspired Versatile Design of an Ultrastrong and Tough Polysaccharide Hydrogel through Programmed Supramolecular Interactions

et al. 2019

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The prerequisites for hydrogels in loadingbearing applications are mechanical strength and toughness. In order to simultaneously achieve both properties, several approaches, including the combination of covalent and noncovalent systems, [1] the design of a synergistic effect triggered by attractive interaction between constituents [2] and the construction of an anisotropic structure through incorporating well-ordered nanomaterials [3] have been developed. As stated above, combining the advantages of two or multiphase, particularly for the typical double-network (DN) system, [4] is significantly effective in fabricating high-performance hydrogels, as has been recently attempted by many researchers. However, the mechanical enhancement of an individual hydrogel through optimizing its internal structure has been rarely focused, despite it being extremely meaningful, particularly for those physically crosslinking hydrogels with many inactive interaction sites. Based on the Lake-Thomas model, both the quantity of polymer chain per unit surface and linkage dissociation energy influence the fracture energy. [5] In natural tissues, such as ligaments, lower water content (60-70 wt%) compared to a synthetic polymer hydrogel (≈90 wt%) imparts strong tensile strength of ≈60 MPa due to the dense gel domain. [6] Inspired by this, hydrogels treated with phase separation [7] or water dehydration [8] methods exhibit exceptional fracture resistance and load-bearing capacity similar to that of biomaterials. Nevertheless, these methods serve as postprocessing treatments, where polymer chains approach limitedly in the presence of crosslinking points and the inactive interaction sites are only partially activated. Thus, according to the mechanism of energy-dissipating sacrificial bonds, if a suitable approach can realize free polymer aggregation accompanied with maximization of supramolecular interactions (e.g., metal-ligand coordination and hydrogen bonds (H-bonds)), the mechanical parameters will further approach their theoretical values. This is the interest of the current work.To justify our hypothesis, a water-soluble natural macromolecule-sodium alginate (SA)-crosslinked with Ca 2+ Simultaneously achieving strength and toughness in soft materials remains a challenge, especially for physically crosslinked hydrogels with many inactive interaction sites. In this work, inspired by the cooking of thick soup in China, a facile method that includes free water evaporation of the diluted pregel solution followed by crosslinking (WEC) is proposed to fabricate polysaccharide hydrogels. Herein, without the constraints of viscosity and crosslinking, polymer chains can homogenously approach as much as possible, thereby enabling the transformation of inactive supramolecular interaction (H-bonding and ionic coordination) sites into active sites until reaching the maximum level. Through facilely tuning the concentrating degree, programmed supramolecular interactions, serving as energy-dissipating sacrificial bonds, impart the hydrogels with ...

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confidence: 92%

Cooking‐Inspired Versatile Design of an Ultrastrong and Tough Polysaccharide Hydrogel through Programmed Supramolecular Interactions

et al. 2019

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“…From previously reported studies with polyacrylamide (PAAm) hydrogel system 26 , the exponent ν is~1 for dilute or semi-dilute state (ϕ p,v < 0.7) and~45 for concentrated state (ϕ p,v > 0.7). For the AINOs, ν is 12.1 at the brittle region, 14.7 at the soft region, and 60 at the transient region with two transition of power laws across the composition.…”

Section: Resultsmentioning

confidence: 99%

Aromatic nonpolar organogels for efficient and stable perovskite green emitters

Park

Kim

et al. 2020

Nat Commun

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Existing gels are mostly polar, whose nature limits their role in soft devices. The intermolecular interactions of nonpolar polymer-liquid system are typically weak, which makes the gel brittle. Here we report highly soft and transparent nonpolar organogels. Even though their elements are only carbon and hydrogen, their elastic modulus, transparency, and stretchability are comparable to common soft hydrogels. A key strategy is introducing aromatic interaction into the polymer-solvent system, resulting in a high swelling ratio that enables efficient plasticization of the polymer networks. As a proof of applicability, soft perovskite nanocomposites are synthesized, where the nonpolar environment of organogels enables stable formation and preservation of highly concentrated perovskite nanocrystals, showing high photoluminescence efficiency (~99.8%) after water-exposure and environmental stabilities against air, water, acid, base, heat, light, and mechanical deformation. Their superb properties enable the demonstration of soft electroluminescent devices that stably emit bright and pure green light under diverse deformations.

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“…11 Lamellar hydrogels, 12 discovered in 1996 by Safinya and Davidson and composed of a phospholipid Lα phase stabilized by a polymer-grafted lipid, were the first example of an elastic 2D self-assembled material at small concentration (<10 wt%). Since then, lamellar hydrogels (LH) were obtained by polymer-stabilization, 13 or by combining a lamellar phase with a gelator. 14,15 The first polymer-free LH, based on surfactant mixtures or lipid/surfactants, are reported only in 2014.…”

Section: Introductionmentioning

confidence: 99%