Martini Coarse-Grained Model for Clay–Polymer Nanocomposites

Abstract

We have developed a coarse-grained (CG) model of a polymer-clay system consisting of organically modified montmorillonite nanoclay as the nanoparticle in accordance with the MARTINI forcefield. We have used mechanical properties and cleavage free energy of clay particle to respectively parameterize bonded and nonbonded interaction parameters for an organically modified montmorillonite (oMMT) clay particle where intergallery Na + ions are replaced by tetramethylammonium (TMA) ions. The mechanical properties were determined from the slope of stress-strain curve and cleavage free energy was determined by allowing for full surface reconstruction corresponding to a slow equilibrium cleavage process. Individual dispersive and polar contributions to oMMT cleavage energy were used for determination of appropriate MARTINI bead types for CG oMMT sheet. The self-consistency of developed MARTINIFF 2 parameters for TMA-MMT -polymer system was verified by comparing estimates for select structural, thermodynamic, and dynamic properties obtained in all-atomistic simulations with that obtained in coarse-grained simulations. We have determined the influence of clay particle on properties of three polymer melts (polyethylene, polypropylene, and polystyrene) at two temperatures to establish transferability of the developed parameters. We have also shown that the effect of clay-polymer interactions on structure-property relationships in polymer-clay nanocomposite system is well captured by Rosenfeld's excess entropy scaling.Accordingly, we have defined each CG MMT bead as consisting of three heavy atoms, viz. / or / ( = ), and CG bead center was put at , , atom. This representation allowed us to preserve the 2:1 layered structure of phyllosilicates through interlayer and intralyer bonds between CG beads (Figure 1). We have used the smaller (fine grained) type-S representation for all three beads, as found to be suitable for ring structures in MARTINI parameterization. 29,40,44 Bonded Potential. We have used a single sheet of TMA-MMT placed in plane with bond connections across the periodic boundary (periodic sheet). The equilibrated structure of Na-MMT of size 3.11 nm × 2.71 nm (924 atoms in 6 × 6 × 1 array of unit cells) was taken from

The Martini Model in Materials Science

“…Martini models for fullerene, [ 67–69 ] carbon nanotubes (CNTs), [ 70–73 ] graphene [ 74–76 ] or MXene [ 77 ] flakes, clay nanoparticles, [ 78 ] and functionalized nanoparticles [ 79–81 ] have also been developed to study their interaction with both other synthetic or biomolecular systems. The C 60 fullerene model developed by Monticelli represents a good parametrization strategy for nanoparticles.…”

“…Martini parameters are available for a wide variety of nanoparticles including fullerenes, [ 67–69 ] carbon nanotubes, [ 70–73 ] and gold [ 79,80,155 ] among others. Apart from their importance to modeling organic electronics, which are the subject of the next section, they have been used to simulate polymer nanoparticle composites, [ 78,80,95,96,155–165 ] self‐assembly of nanoparticles, [ 79,166–168 ] and solution processing of nanoparticles. [ 76,77,85,86 ]…”

“…[ 172 ] Additionally, the self‐assembly of asphaltenes [ 82,176–179 ] has also been investigated, as their stability in solution strongly depends on temperature, pressure, and composition and is important in process and energy engineering. Other applications in the field of nanoparticle composite materials include polymer/graphene, [ 75 ] polymer/graphite, [ 180 ] polymer/clay [ 78 ] composites, and polymer–CNT–protein matrices for applications in the field of tissue regeneration. [ 181 ]…”

The Martini Model in Materials Science

“…Martini models for fullerene [58][59][60], carbon nanotubes (CNTs) [61][62][63][64], graphene [65][66][67] or MXene [68] flakes, clay nanoparticles [69], and functionalized nanoparticles [70][71][72] have also been developed to study their interaction with both other synthetic or biomolecular systems. The C 60 fullerene model developed by Monticelli represents a good parametrization strategy for nanoparticles.…”

Martini Coarse-Grained Model of Hyaluronic Acid for the Structural Change of Its Gel in the Presence of Monovalent and Divalent Salts

“…Martini-based models have also been applied to understand the cross interactions of protein–polymer complex formations [ 21 ]. Several recent reports justify the application of Martini CG models to a variety of molecules, including calcein fluorescent dye [ 22 ], polyethylenimine [ 23 ], clay–polymer nanocomposites [ 24 ], poly(3,4-ethylenedioxythiophene) (PEDOT) [ 25 ], etc. Moreover, Martini-based CG models have been successfully applied to study supramolecular polymer assemblies such as benzene-1,3,5-tricarboxamide (BTA) [ 26 , 27 ] and peptide amphiphiles [ 28 , 29 ].…”