Adsorption-induced deformation of hierarchical organised carbon materials with ordered, non-convex mesoporosity

Ludescher, Lukas; Morak, Roland; Braxmeier, Stephan; Balzer, Christian; Putz, Florian; Büsch, Sebastian; Hüsing, Nicola; Reichenauer, Gudrun; Gor, Gennady Y.; Paris, Oskar

doi:10.1080/00268976.2021.1894362

Cited by 6 publications

(16 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For some problems with specific geometries or heterogeneous surfaces, , calculating the variation is a very laborious task, because of the complex structure of the system’s free energy. For example, to study graphene nanobubbles by classical density functional and elasticity theories, it is important to know the energy of the entire system and density distribution at the same time because this system has additional constraints for fluid molecules.…”

Section: Variation-free Methodsmentioning

confidence: 99%

“…All these interactions might be taken into account in a different way in Helmholtz free energy, and it is also necessary to calculate the variation for these additional terms. In addition to the fact that it is necessary to choose a physical model and the corresponding type of free energy, the problems under study are often endowed with specific geometric properties, and these properties dictate the type of coordinate system for DFT model. , For some physical systems, it is not always possible to calculate the Helmholtz energy variation without any simplifications of the model (especially for systems with additional constraints), because of the free-energy complex structure. The use of the VF-DFT will detour these barriers and get sufficiently accurate solutions.…”

Section: Variation-free Methodsmentioning

confidence: 99%

“…Therefore, it is necessary to construct various approximations that describe certain physical phenomena with precise accuracy. Recently developed approaches have allowed one to take into account the heterogeneity of the surface ,, and adsorption-induced deformation in nonconvex materials, or combine DFT with elasticity theories to study graphene nanobubbles . There are certain subtleties in the last application; fluid in such a system is under additional constraints, and it is crucial to know both the value of system energy and equilibrium density at the same time.…”

Section: Introductionmentioning

confidence: 99%

“…The most significant change involves the variation of attraction interaction. Depending on what material is being investigated, the variation of free energy must be calculated in different coordinate systems, ,, which means variations should be recalculated in appropriate coordinates. Moreover, Statistical Associating Fluid Theory (SAFT) is usually used to describe polymers or other complex fluids, which considers dispersion, association, and chain contributions in Helmholtz energy .…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Variation-Free Approach for Density Functional Theory: Data-Driven Stochastic Optimization

Kanygin

Nesterova

Lomovitskiy

et al. 2022

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Density functional theory (DFT) is an efficient instrument for describing a wide range of nanoscale phenomena: wetting transition, capillary condensation, adsorption, etc. In this paper, we suggest a method for obtaining the equilibrium molecular fluid density in a nanopore using DFT without calculating the freeenergy variationVariation-Free Density Functional Theory (VF-DFT). This technique can be used to explore confined fluids with a complex type of interactions, additional constraints, and, to speed up calculations, which might be crucial in an inverse problem. The fluid density in VF-DFT approach is represented as a decomposition over a limited set of basis functions. We applied principal component analysis (PCA) to extract the basic patterns from the density function and take them into account in the construction of a set of basis functions. The decomposition coefficients of the fluid density by the basis were sought by stochastic optimization algorithms: genetic algorithm (GA) and particle swarm optimization (PSO), to minimize the free energy of the system. In this work, two different fluids were studied: nitrogen at a temperature of 77.4 K and argon 87.3 K, at a pore size of 3.6 nm, and the performance of optimization algorithms was compared. We also introduce the Hybrid Density Functional Theory (H-DFT) approach based on stochastic optimization methods and the classical Picard iteration method to find the equilibrium fluid density starting from the physically appropriate solution. The combination of Picard iteration and stochastic algorithms helps to significantly speed up the calculations of equilibrium density in the system without losing the quality of the solution, especially in cases with the high relative pressure and expressed layering structure.

show abstract

Section: Variation-free Methodsmentioning

confidence: 99%

Section: Variation-free Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Variation-Free Approach for Density Functional Theory: Data-Driven Stochastic Optimization

Kanygin

Nesterova

Lomovitskiy

et al. 2022

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

show abstract

“…In these materials, reciprocal actions between the deformation in different pores may induce unexpected effects and thus arouse increasing attention. Recent work ,, based on adsorption dilatometry and small-angle neutron scattering (SANS) presents a good example for elucidating the contributions of micropores and mesopores in the sorption-deformation coupling in the presence of hierarchical porosity. However, such experimental studies normally entail a well-ordered material, such as structured silica and organized carbon .…”

Section: Introductionmentioning

confidence: 99%

Sorption-Deformation Interplay in Hierarchical Porous Polymeric Structures Composed of a Slit Pore in an Amorphous Matrix

et al. 2023

View full text Add to dashboard Cite

Prevailing absorbents like wood-derived porous scaffolds or polymeric aerogels are normally featured with hierarchical porous structures. In former molecular simulation studies, sorption, deformation, and coupled sorption-deformation have been studied for single-scale materials, but scarcely for materials where micropores (<2 nm) and mesopores (2−50 nm) coexist. The present work, dealing with a mesoscopic slit pore between two slabs of microporous amorphous cellulose (AC), aims at modeling sorption-deformation interplay in hierarchical porous cellulosic structures inspired by polymeric modern adsorbents. Specifically, the atomic system is modeled by a hybrid workflow combining molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations. The results clarify the multiple sorption/deformation mechanisms in porous materials with different slit-pore sizes, including water filling in micropores, surface covering at the solid−air interface, and subsequent capillary condensation in mesopores. In particular, before the onset of capillary condensation, the sorption behavior of the AC matrix in the hybrid system is almost the same as that of bulk AC, in which sorption and deformation enhance each other through sorptioninduced swelling and additional sorption in the newly created voids. Upon capillary condensation, the interaction between the micropores and the mesopore emerges. Water molecules in the mesopore exert a negative hydrostatic pressure perpendicular to the slab surface on the matrices, resulting in an increase in porosity and water content, a decrease in distance between the centers of mass (COMs) of the slabs, and thus a thinning of the slit pore. As described by Bangham's Law, the surface area of the rough slitpore slab increases proportionally to the surface energy variation during surface covering. For a system composed of a compliant polymer like AC, however, the surface area enlargement does not result in an in-plane swelling as expected but instead in an in-plane shrinkage along with an increase in local roughness or irregularity (an accordion effect).

show abstract

Surface morphology regulates the sorption-induced deformation of mesoporous media

Chen

2022

Microporous and Mesoporous Materials

View full text Add to dashboard Cite

Adsorption-induced deformation of hierarchical organised carbon materials with ordered, non-convex mesoporosity

Cited by 6 publications

References 55 publications

Variation-Free Approach for Density Functional Theory: Data-Driven Stochastic Optimization

Variation-Free Approach for Density Functional Theory: Data-Driven Stochastic Optimization

Sorption-Deformation Interplay in Hierarchical Porous Polymeric Structures Composed of a Slit Pore in an Amorphous Matrix

Surface morphology regulates the sorption-induced deformation of mesoporous media

Contact Info

Product

Resources

About