Poro-elasto-capillary wicking of cellulose sponges

Ha, Jun Seok; Kim, Jung‐Chul; Jung, Young Bok; Yun, Giseok; Kim, Do-Nyun; Kim, Ho-Young

doi:10.1126/sciadv.aao7051

Cited by 48 publications

(40 citation statements)

References 37 publications

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“…On the one hand, to explain these results, structures made of a network of channels with connections with a probability of passage [28,29], or with a double permeability [14], were suggested, which are nevertheless not fully consistent with the effective structure of hardwood. On the other hand, a dynamics differing from that expected from the standard Washburn process has been observed for bi-porous systems [30][31][32][33] and other peculiar effects were observed with specific pore shapes [25,34,35]. Among these materials were cellulose sponges [31,32] made of macropores (few millimeters) connected by micropores (few micrometers), and a solid structure formed of sheets able to adsorb water so that the structure swells when in contact with water.…”

Section: A Paradoxical Capillary Imbibition In Hardwoodsmentioning

confidence: 98%

“…On the other hand, a dynamics differing from that expected from the standard Washburn process has been observed for bi-porous systems [30][31][32][33] and other peculiar effects were observed with specific pore shapes [25,34,35]. Among these materials were cellulose sponges [31,32] made of macropores (few millimeters) connected by micropores (few micrometers), and a solid structure formed of sheets able to adsorb water so that the structure swells when in contact with water. The late stage of water imbibition dynamics is slowed down by micropore deformation and merging, resulting from deformations of the hygroscopic structure [32].…”

Section: A Paradoxical Capillary Imbibition In Hardwoodsmentioning

confidence: 98%

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Wetting enhanced by water adsorption in hygroscopic plantlike materials

Zhou

Caré

King

et al. 2019

Phys. Rev. Research

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Water inside hygroscopic porous media such as plantlike systems can be found either freely penetrating in capillaries or absorbed into the solid phase (bound water). Here we demonstrate that the wetting properties (contact angle) of liquid along cell walls significantly depend on the amount of bound water absorbed: a change from poor to good wetting is observed when cell walls are saturated with bound water, which allows liquid displacement. We further show that this process is operative in hydrogels, suggesting that this might be a general property of porous hygroscopic systems. As a consequence, imbibition dynamics is controlled by water adsorption and diffusion in the walls, and even if the dynamics of capillary imbibition is strongly damped (by several orders of magnitude), water can freely climb over significant heights as long as sufficient water has been adsorbed into cell walls or in other hygroscopic walls. Under these conditions, the imbibition process in such systems is not described by the standard model but is analogous to the propagation of a front of solidification in a liquid. This process might contribute to the regulation of water absorption in unsaturated wood, allowing it to store available bound water in progressively higher depths, instead of leaving free water rapidly flow through it. Such a mechanism may be explored to design porous materials with tunable liquid adsorption timings for pharmaceutical or chemical engineering applications.

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Section: A Paradoxical Capillary Imbibition In Hardwoodsmentioning

confidence: 98%

Section: A Paradoxical Capillary Imbibition In Hardwoodsmentioning

confidence: 98%

Wetting enhanced by water adsorption in hygroscopic plantlike materials

Zhou

Caré

King

et al. 2019

Phys. Rev. Research

View full text Add to dashboard Cite

show abstract

“…The volume of hygroscopic materials, especially cellular materials, usually swell after absorbing water. The structural changes of these samples against the changes of humidity or processes of water condensation/evaporation can, of course, be studied by in situ observations in the ESEM chamber . Ha et al investigated the evolution of microscale wall pores in hygroscopically responsive multiscale porous materials during the wetting process by in situ observation under ESEM.…”

Section: Recent Applicationsmentioning

confidence: 99%

“…They found that the deformation underwent two steps, which were the growth of pore size and the coalescence of the expanded pores. On the contrary, the deformation of sponge was insignificant when RH was below 90%, indicating that water molecules hardly infiltrated into the sponge until the vapor pressure reaches a critical value . Similarly, Kang et al directly imaged the swelling of a film by ESEM to study the effect of humidity on swelling behavior.…”

Section: Recent Applicationsmentioning

confidence: 99%

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Applications of ESEM on Materials Science: Recent Updates and a Look Forward

et al. 2019

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The microscopic understanding of materials relies on the development of microscopy. Historically, the technological evolution from optical microscopes to electron microscopes has directly stimulated many discoveries of new physical and chemical fundamentals as well as advanced materials. Scanning electron microscopy (SEM) is, undoubtedly, the most widely used tool for microscopic characterization in modern materials science. Especially, the incorporation of a gas pressure around the sample area of conventional SEM, i.e., the environmental scanning electron microscope (ESEM), has opened new possibilities in observing samples in their natural states, leading to unprecedented chances for studying the details of biological, organic, and hydrated samples. What is more, in recent years, in situ ESEM studies concerning materials change and chemical reactions have played a more important role in the field of materials science. Herein, the recent applications of ESEM in materials science are comprehensively reviewed, in terms of common static observations for various materials and in situ investigations of dynamic processes in controlled experimental environments. Moreover, the problems concerning state‐of‐the‐art ESEM experiments are discussed, as well as possible solutions. Looking forward, the rapid developments on instrumentation and fundamental science of ESEM can bring a clear vision of materials in the near future.

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Liquid Metal Microdroplet‐Initiated Ultra‐Fast Polymerization of a Stimuli‐Responsive Hydrogel Composite

Zhang,

Liao,

Liu

et al. 2023

Adv Funct Materials

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Recent advances in composite hydrogels achieve material enhancement or specialized stimuli‐responsive functionalities by pairing with a functional filler. Liquid metals (LM) offer a unique combination of chemical, electrical, and mechanical properties that show great potential in hydrogel composites. Polymerization of hydrogels with LM microdroplets as initiators is a particularly interesting phenomenon that remains in its early stage of development. In this work, an LM‐hydrogel composite is introduced, in which LM microdroplets dispersed inside the hydrogel matrix have dual functions as a polymerization initiator for a polyacrylic acid‐poly vinyl alcohol (PAA/PVA) network and, once polymerized, as passive inclusion to influence its material and stimuli‐responsive characteristics. It is demonstrated that LM microdroplets enable ultra‐fast polymerization in ≈1 min, compared to several hours by conventional polymerization techniques. The results show several mechanical enhancements to the PAA/PVA hydrogels with LM‐initiated polymerization. It is found that LM ratios strongly influence stimuli‐responsive behaviors in the hydrogels, including swelling and ionic bending, where higher LM ratios are found to enhance ionic actuation performance. The dual roles of LM in this composite are analyzed using the experimental characterization results. These LM‐hydrogel composites, which are biocompatible, open up new opportunities in future soft robotics and biomedical applications.

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Poro-elasto-capillary wicking of cellulose sponges

Abstract: Capillary rise of water in porous cellulose sponges is investigated considering hygroscopic shape evolutions of micropores.

Cited by 48 publications

References 37 publications

Wetting enhanced by water adsorption in hygroscopic plantlike materials

Wetting enhanced by water adsorption in hygroscopic plantlike materials

Applications of ESEM on Materials Science: Recent Updates and a Look Forward

Liquid Metal Microdroplet‐Initiated Ultra‐Fast Polymerization of a Stimuli‐Responsive Hydrogel Composite

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