Effective negative swelling of hydrogel-solid composites

Dynamics of solvent release from polymer gels with small solvent-filled cavities is investigated starting from a thermodynamically consistent and enriched multiphysics stress-diffusion model. Indeed, the modeling also accounts for a new global volumetric constraint which makes the volume of the solvent in the cavity and the cavity volume equal at all times. This induces a characteristic suction effect into the model through a negative pressure acting on the cavity walls. The problem is solved for gel-based spherical microcapsules and microtubules. The implementation of the mathematical model into a finite element code allows to quantitatively describe and compare the dynamics of solvent release from full spheres, hollow spheres, and tubules in terms of a few key quantities such as stress states and amount of released solvent under the same external conditions.

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“…[18] and then improved in Refs. [14,27,31,32] with special emphasis on swelling and shrinking dynamics.…”

Section: Stresses and Diffusion In Polymer Gelsmentioning

confidence: 99%

“…The Flory-Rehner thermodynamic model, largely used in literature when continuum models of gels are considered [15][16][17][18]20], assumes a neo-Hookean free elastic energy and a mixing free energy derived by statistical mechanics procedures. The free energies (see for details [14,17,18,32]…”

Section: Stresses and Diffusion In Polymer Gelsmentioning

confidence: 99%

Modeling solvent dynamics in polymers with solvent-filled cavities

2020

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“…For the latter, Lakes [1,2] was the first to demonstrate that auxetic (negative Poisson's ratio) foams can be produced by compression and heating so as to introduce a re-entrant microstructure; auxetic behavior has also been shown achievable by other microstructural designs (see related reviews [3][4][5][6][7][8][9][10][11][12] and monographs [13,14] ). Likewise, both naturally occurring and artificially made materials that exhibit negative thermal expansion (NTE), [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] negative compressibility (NC), [30][31][32][33][34][35][36][37][38][39][40] and negative moisture expansion (NME) [41][42][43][44][45] -which is also known as negative swelling and negative hygroscopic expansion-properties behave the way they do due to their microstructure. Controlled NTE in lattices has been known for about a q...…”

Section: Introductionmentioning

confidence: 99%

An Auxetic Metamaterial with Tunable Positive to Negative Hygrothermal Expansion by means of Counter‐Rotating Crosses

Lim

2021

Physica Status Solidi (b)

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A type of mechanical metamaterial is proposed, whereby the effective coefficients of thermal and moisture expansions (CTE and CME, respectively) can be tuned from positive to negative values while maintaining a consistently auxetic (negative Poisson's ratio) behavior for the overall structure. Each unit consists of a pair of equal‐armed crosses pin jointed at their centers, whereas their ends are connected via bridging beams using pin joints to facilitate free rotation. The bridging beams are of lower modulus and higher hygrothermal expansivity to permit negativity in metamaterial's overall Poisson's ratio and hygrothermal expansion. Two sets of effective Young's modulus, CME and CTE models are developed—one set for large deformation and the other for infinitesimal deformation. Results indicate that the effective Young's modulus is reduced while the expansion coefficients become more negative as the inclination angle of the equal‐armed crosses increases, and that the application of tensile and compressive loads increases and decreases the effective Young's modulus, respectively. The establishment of effective zero thermal and moisture expansion conditions facilitates the application of the metamaterial structure that requires auxetic property within highly fluctuating environmental condition.

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“…On the other hand, it was recently recognized that the microscale interactions between proteins embedded in biological membranes can promote the assembly of ordered protein structures [5][6][7] and can also facilitate the entry of viral particles into cells [8]. Furthermore, in mechanical metamaterials [9] the geometry, topology and contrasting elastic properties of different materials, are exploited to obtain extraordinary functionalities, such as shape morphing [10,11], mechanical cloaking [12][13][14], negative Poisson's ratio [15][16][17][18][19], negative thermal expansion [20,21], effective negative swelling [22][23][24], and tunable band gaps [25][26][27]. At the heart of these functionalities are deformation patterns of such materials with holes and inclusions.…”

Section: Introductionmentioning

confidence: 99%

Elastic multipole method for describing linear deformation of infinite 2D solid structures with circular holes and inclusions

Sarkar,

Cebron,

Brojan

et al. 2019

Preprint

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Effective negative swelling of hydrogel-solid composites

Cited by 23 publications

References 34 publications

Modeling solvent dynamics in polymers with solvent-filled cavities

Modeling solvent dynamics in polymers with solvent-filled cavities

An Auxetic Metamaterial with Tunable Positive to Negative Hygrothermal Expansion by means of Counter‐Rotating Crosses

Elastic multipole method for describing linear deformation of infinite 2D solid structures with circular holes and inclusions

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