Predictions of Thermo‐Mechanical Properties of Cross‐Linked Polyacrylamide Hydrogels Using Molecular Simulations

Abstract

Hydrophilic acrylamide-based hydrogels are emerging platforms for numerous applications, but our ability to fully exploit these materials is currently limited. A deepening of our understanding of molecular-level structure/property relationships in hydrogels is crucial to progressing these efforts. Such relationships can be challenging to elucidate on the basis of experimental data alone. Here, we use molecular simulations as a complementary strategy to reveal the molecular-level phenomena that govern the thermo-mechanical properties of hydrogels. We focus on acrylamide-based hydrogels cross-linked with N,N'methylenebisacrylamide, generated using our previously-established computational crosslinking procedure. We find the water content to be a key determinant in the elastic response of these hydrogels, with enhanced tensile and shear properties at low water content. However, we also find increasing water content enhances the hydrogel's thermal conductivity, with the dominant contribution arising from the non-bonded contributions to the heat flux. In addition, chemical cross-linking improved the heat transfer properties of the hydrogel, whereas a reduction in convective heat transfer was predicted with an increase in hydrogel crosslinking. Our simulations provide a rational basis for designing and testing customized hydrogel formulations for maximising both thermal conductivity and mechanical properties.

Thermal conductivity of molybdenum disulfide nanotube from molecular dynamics simulations

“…Different type of MoS2NT is constructed by rolling up SLMoS2 based on specific lattice vector r = ma1 + na2, where the lattice constants of the primitive cell are a1= a2=3.147 Å (as shown in figure 1a). Noting that our study only focuses on armchair nanotube (aNT, m=n) and zigzag nanotube (zNT, The classical non-equilibrium molecular dynamics (NEMD) method has been employed in the calculation of thermal properties [12][13][14][15][16][17]. The thermal conductivity is calculated based on the Fourier's law of heat conduction as…”

Application of atomic stress to compute heat flux via molecular dynamics for systems with many-body interactions

“…While rigid formulation has been put forward for both obtaining local pressure [8,9] and handling many-body interactions [5,[10][11][12], approximations using atomic stress have also been applied with acceptable accuracy and a much greater ease of implementation [13][14][15], which is also the case for the widely used molecular dynamics package LAMMPS [16]. Owing to the similarity of pressure and heat flux formulation, the same atomic stress approximation has been applied to computing heat flux and thermal conductivity without any rigid validation for either molecular dynamics systems containing simple many-body interactions such as angle, torsion, or improper [17][18][19][20][21][22][23][24][25][26], or for more complex ones such as Stillinger-Weber, Tersoff, or AIREBO potentials .…”

Efficient Interfacial Solar Steam Generator with Controlled Macromorphology Derived from Flour via “Dough Figurine” Technology

“…For the C‐FFNC absorber, the solar light trap formed by the surface pores and the carbonized nature with black color can form a high optical absorption (95.5% in the visible range), which provide sufficient solar energy source. The thermal conductivity of the flour‐based carbon foam is 0.09 W mK −1 , one order of magnitude lower than that of pure water (0.60 W mK −1 at room temperature) . The low thermal conductivity of C‐FFNC enables the captured solar energy to be confined to the air–liquid surface, which reduces the heat conduction loss to the bulk water and promote the formation of localized hot area as shown in Figure g.…”

“…The thermal conductivity of the flour-based carbon foam is 0.09 W mK À1 , one order of www.advancedsciencenews.com www.entechnol.de magnitude lower than that of pure water (0.60 W mK À1 at room temperature). [53,54] The low thermal conductivity of C-FFNC enables the captured solar energy to be confined to the air-liquid surface, which reduces the heat conduction loss to the bulk water and promote the formation of localized hot area as shown in Figure 1g. Moreover, the rich pore structures (porosity, 59.79%) and hydrophilicity of C-FFNC facilitates the water transport from bulk water transport to the air-liquid interface.…”