Mechanics of multi-stimuli temperature-responsive hydrogels

“…However, stimuli-responsive polymers represent an interesting alternative to traditional energy harvesting approaches. Dielectric elastomers (DEs), which can experience large deformations in response to electric excitation [12,13], as well as gels, capable of huge volumetric deformations upon solvent absorption [14][15][16], are examples of such materials. Commonly, DEs have been used for energy storage and energy harvesting by harnessing energy conversion mechanisms [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Energy harvesting with dielectric elastomer tubes: active and (responsive materials-based) passive approaches

Hanuhov,

Brighenti,

Cohen

2024

Smart Mater. Struct.

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Mechanical to electrical energy conversion is a well-established energy transduction approach. However, cases in which a mechanical energy source is not available call for new approaches to harvest electrical energy. In the present study, we demonstrate energy harvesting in soft dielectric elastomer (DE) tubes. Broadly, energy harvesting is obtained through inflation of the tube, electrical charging of the DE layer, and deflation, which results in a decrease in capacitance and an increase in voltage. We propose two methods to mechanically charge (or inflate) the system: (1) active, in which the tube is inflated through the application of mechanical pressure, and (2) passive, in which a passive cylindrical component placed inside the DE tube deforms radially in response to an environmental stimulus such as thermal excitation or water uptake and inflates the DE tube. To demonstrate passive charging, we consider gels as the passive component and employ well-known models with the properties of the commonly employed DE VHB 4910 to simulate the mechanical response of the system and estimate the harvested electrical energy. Our findings reveal that energy-densities in the order of ∼ 10 − 50mJ/cm3 can be harvested. The proposed approach and the inclusion of a passive component to mechanically charge the system opens new opportunities to generate energy in environments lacking traditional mechanical energy sources.

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“…The poly( N -isopropylacrylamide) (PNIPAM) hydrogel is the most extensively studied thermoresponsive hydrogel, swelling under the volume phase transition temperature (VPTT) while shrinking above VPTT. The reversible volume change under temperature stimuli endows the PNIPAM hydrogel with wide applications in artificial muscle, , bioengineering, and drug delivery. , Moreover, when photothermal agents are embedded in the PNIPAM hydrogels, under NIR light, they can absorb and convert photoenergy into thermal energy, leading to the volume shrinkage of the PNIPAM hydrogel. − Furthermore, the optical transition has also been used in smart window applications. , …”

Section: Introductionmentioning

confidence: 99%

Artificial Skin with Patterned Stripes for Color Camouflage and Thermoregulation

Liu,

Zhou,

Meng

et al. 2023

ACS Appl. Mater. Interfaces

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Chameleons are famous for their quick color changing abilities, and it is commonly assumed that they do this for camouflage. However, recent reports revealed that chameleons also change color for body temperature regulation. Inspired by the structure of the panther chameleon's skin, a stripe-patterned poly(N-isopropylacrylamide) (PNIPAM) and polyacrylamide (PAM) hydrogel film with a laminated structure is fabricated in this work; thus, both camouflage and thermoregulation can be achieved through controlling Vis and NIR light effectively. For the PNIPAM stripe, the upper layer is the native PNIPAM hydrogel and the lower layer is the carbon nanotube-composited PNIPAM hydrogel. Thus, the PNIPAM stripe is capable of reaching 28 °C at a low environmental temperature (12 °C) and a low radiation intensity (20 mW cm −2 ), while preventing the body temperature from rising by changing to white under a strong radiation intensity (100 mW cm −2 ). For the PAM stripe, the upper layer combines colloidal photonic crystals and displays a tunable structural color by stretching, and the lower layer is mixed with PNIPAM microgels for thermal regulation. Through the fabrication of multifunctional patterns, the film can achieve both dynamic structural color and thermoregulation by precisely controlling solar radiation absorption, scattering, and reflection. More importantly, in the stripe-patterned system, the shrinkage of the PNIPAM stripes can effectively trigger the elongation of the PAM stripe, which endows the structural color changing process to be self-powered completely. The performances show that the stripe-patterned film may have potential applications in intelligent coatings, especially in areas with large temperature differences during the day such as high plains.

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Mechanics of multi-stimuli temperature-responsive hydrogels

Cited by 10 publications

References 52 publications

Mechanics and physics of the light-driven response of hydrogels

Mechanics and physics of the light-driven response of hydrogels

Energy harvesting with dielectric elastomer tubes: active and (responsive materials-based) passive approaches

Artificial Skin with Patterned Stripes for Color Camouflage and Thermoregulation

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