Mechanochemical Turbine: A New Power Cycle

Sussman, M. V.; Katchalsky, A.

doi:10.1126/science.167.3914.45

Cited by 94 publications

(43 citation statements)

References 3 publications

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“…The details for the measurements of the heats of swelling and the picture analysis with the microscope-VTR system are in our previous paper.' Figure 1 shows the swelling ratio Vt/Vo obtained by microscopic observation; V, is the volume at time t 4 and Vo is the volume before swelling. The bars show the standard deviations.…”

Section: Methodsmentioning

confidence: 99%

Swelling of hydrophilic polymers. II

Ogawa

Yamano

Miyagawa

1993

J of Applied Polymer Sci

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SYNOPSISThe swelling of five types of Sephadex that are either nonionic ( G ) or possess one of four different ionic groups [sodium carboxymethyl (CM) , sodium sulfopropyl (SP) , diethylaminoethyl chloride (DEAE), diethyl-(2-hydroxypropyl) aminoethyl chloride (QAE) ] in the same skeleton of the molecule has been studied by picture analysis and by calorimetry. Inducing dissociation of the ionic group in the polymer skeleton increased the water swelling. By the addition of sodium chloride, the maximum swelling volume of nonionic Sephadex was only slightly decreased. However, that of ionic polymers was considerably decreased. The variation of the apparent first-order rate constant of the swelling and that of the maximum swelling volume show the same tendency. The maximum heats of swelling were 93.2 ? 7.1 J g-' for G, 128.8 ? 9.1 J g-' for CM, 92.3 -t 8.0 J g-' for SP, 68.8 k 10.5 J g-' for DEAE, and 67.0 +. 7.2 J g-' for QAE and did not depend on the concentration of sodium chloride. From the results obtained, we conclude that the nonionic Sephadex swells only by hydration but that ionic Sephadexes swell mainly by the osmotic pressure due to the counterions of the ionic groups and that the swelling ratio is not dependent on the kinds of ions but on the ionic concentration. Most of the water in the gels of ionic Sephadexes is free water that does not interact with the Sephadexes. 0

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Section: Methodsmentioning

confidence: 99%

Swelling of hydrophilic polymers. II

Ogawa

Yamano

Miyagawa

1993

J of Applied Polymer Sci

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“…The mechanochemical engine generated high power-to-weight ratio of 30 mW/g (collagen) which was close to that of skeletal muscles (50 mW/g). Furthermore, Sussman and Katchalsky built chemomechanical turbines [84] and thermodynamic study of mechanochemical availability was theoretically investigated [85]. The power density and efficiency of energy conversion of the mechanochemical turbine attained as high as 0.79 J/g and 40 %, respectively.…”

Section: Salt-responsive Gelsmentioning

confidence: 99%

Progress and Current Status of Materials and Properties of Soft Actuators

Okuzaki

2014

Soft Actuators

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In this chapter, brief history and current status of soft actuators made of various materials driven by different stimuli are described with typical references as milestones of the progress. The soft actuators originated from unique characteristics of cross-linked polymer gels for understanding their physical and chemical properties of dimensional changes and phase transitions induced by various environmental stimuli such as pH, salt, solvent, heat, light, and electric field. The 'explosion' of research and development of soft actuators in the 1990s extended over a variety of materials such as conductive polymers, elastomers, carbon nanotubes, and biomaterials, which had driven further progress in soft actuators not only from the fundamental viewpoint of basic science and materials chemistry and physics but also from the engineering viewpoint for the practical applications to light-weight, low-cost, no-noise, less-pollution, and high-efficiency micro-and macro-artificial muscles and soft robotic systems.

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“…The possibility of using these polymeric gel muscles or actuators for mechanochemical engines and turbines was originally discussed by Steinberg, Oplatka and Katchalsky [12] and Sussman and Katchaisky [13].…”

Section: Fixed Chargesmentioning

confidence: 99%

<title>Relationship between the volumetric strain and the pH in ionic polymeric gels</title>

Shahinpoor¹

1993

SPIE Proceedings

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A theoretical model is presented for the derivation of a mathematical relationship between the volumetric strain, c, of an ionic polymeric gel and its pH. The model presented also applies to polyelectrolytes in aqueous solutions. The derivation uses an expression for the total electrostatic free energy per single polyelectrolyte molecule which involves a quasi-Debye curvature, the local absolute temperature, the geometric features of polyelectrolyte molecule, the dielectric constant of the gel as well as the local ionic concentrations for the fixed and the mobile charges. The gradient of the free energy with respect to the number of fixed ions is then related to the pH, i.e., the local concentration of hydrogen ions H+, the absolute temperature T and the degree of ionization a which is defined as the ratio of the number of moles of 11+ to the number of moles of the ionizable groups fixed to the ionic gel network. Subsequently, the gradient of the free energy is related to the volumetric strain, v' of the ionic gel network. The relationship obtained between the pH and the volumetric strain, v' of the ionic gel is highly nonlinear and does depict a trend compatible with experimental evidence on rapid phase transformation in ionic gels at certain critical values of the pH. For infinitesimal strains, the derived expression between the pH and the volumetric strain fv is shown to become approximately linear. 2-INTRODUCTIONIonizable polymeric gels composed of ionic networks of randomly cross-linked macromolecules of polyelectrolytes have recently been investigated as electrically controllable artificial muscles and smart materials for medical, robotic, and other engineering applications. A polymer gel is defined as a cross-linked polymer network swollen in a liquid medium. These gels possess an ionic structure in the sense that they are generally composed of a number of fixed ions pertaining to sites of various polymer cross-links and segments and mobile ions (counter ions) due to the presence of a solvent which is electrolytic. Figure 1 below depicts a very simplistic molecular picture of such ionic gels. Katchalsky [1], and Kuhn[2] originally reported on the possibility that certain copolymers . can be chemically contracted or swollen like a synthetic muscle (pH muscle) by changing the pH of the solution containing them. As originally reported by Kuhn, Horgitay, Katchalsky, and Eisenberg [3], a three-dimensional network, consisting of polyacrylic acid, can be obtained by heating a foil of polyacrylic acid containing a polyvalent alcohol such as glycerol or polyvinyl alcohol. The resulting three-dimensional networks are insoluble in water but swell enormously in water on addition of alkali and contract enormously on addition of acids. Linear reversible dilations and contractions of the order of more than 1000 percent has been observed for ionic gel muscles made with polyacrylonitrile (PAN) fibers (Shahinpoor and Mojarrad [4]). Furthermore, as reported recently by Li and Tanaka [5], the structural deformation (swelling ...

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Mechanochemical Turbine: A New Power Cycle

Cited by 94 publications

References 3 publications

Swelling of hydrophilic polymers. II

Swelling of hydrophilic polymers. II

Progress and Current Status of Materials and Properties of Soft Actuators

<title>Relationship between the volumetric strain and the pH in ionic polymeric gels</title>

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